JP2013046085A - Piezoelectric vibration element, piezoelectric vibrator, electronic device, and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact high-frequency piezoelectric vibration element that has a small CI value and suppresses nearby spurious frequencies while using a fundamental wave.SOLUTION: A piezoelectric vibration element 1 includes: a piezoelectric substrate 10 that has a rectangular vibration region 12 and a support portion 13; excitation electrodes 25a and 25b; and lead electrodes 27a and 27b. The support portion 13 includes a first support portion 14, a second support portion 15, and a third support portion 16. The second support portion 15 is provided with at least one slit 20. The excitation electrodes 25a and 25b and the lead electrodes 27a and 27b are made of different materials and have different thicknesses.

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, the piezoelectric vibrator having the above-described structure has the CI value of the main vibration and the adjacent spurious CI value ratio (= CIs / CIm, where CIm is the CI value of the main vibration, and CIs is the CI value of the spurious. It has been found that there is a problem that one example cannot satisfy the requirement. 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.

  Application Example 1 A piezoelectric vibration element according to the present invention includes a piezoelectric substrate having a vibration part including a vibration region, a pair of excitation electrodes disposed so as to face the vibration region on both sides, and the pair of excitation electrodes. And a lead electrode provided to extend on the support portion, and the thickness of the excitation electrode is t1, and the thickness of the lead electrode is The piezoelectric vibration element is characterized by satisfying t1 <t2 when t2.

  According to this configuration, there is an effect that the excitation electrode plateback (frequency reduction amount) can be set appropriately, the ohmic cross of the lead electrode can be reduced, and the lead electrode can withstand wire bonding.

  Application Example 2 In the piezoelectric vibration element, the lead electrode is provided on the support portion, the first lead electrode having a thickness t1 that is electrically connected to the excitation electrode, and has a film thickness. The piezoelectric vibration element according to Application Example 1, wherein the piezoelectric vibration element is configured by electrically connecting a second lead electrode of t2.

  According to this configuration, the first lead electrode having the same thickness as the excitation electrode having the film thickness t1 is set to an appropriate plate back amount, and the film thickness t2 of the lead electrode is set to a film thickness having no ohmic cross. As a result, the CI value of the piezoelectric vibration element is reduced.

  Application Example 3 In the piezoelectric vibration element, the lead electrode is configured such that the first lead electrode and the second lead electrode overlap at least in a part of the region. The piezoelectric vibration element according to Application Example 1 or 2.

  According to this configuration, the first lead electrode and the second lead electrode are laminated in part, there is no conduction failure between the excitation electrode and the lead electrode, the CI value can be reduced, There is an effect that a piezoelectric vibration element with less spurious can be obtained.

  Application Example 4 In the piezoelectric vibration element, the lead electrode is formed by sequentially stacking a first layer and a second layer on the piezoelectric substrate, and the excitation electrode is formed on the piezoelectric substrate in a third order. The piezoelectric vibration element according to any one of Application Examples 1 to 3, wherein the first layer and the fourth layer are stacked.

  According to this configuration, in a part of the laminated portion of the lead electrode, the first layer and the second layer are sequentially laminated, and then the third layer and the fourth layer are sequentially laminated by the excitation electrode. Therefore, the conductivity of the laminated part is sufficient. In addition, the adhesive force between the lead electrode and the piezoelectric substrate is increased, and there is an effect that it can sufficiently withstand wire bonding.

  Application Example 5 In the piezoelectric vibration element, the first electrode, the second layer, the third layer, and the fourth layer are sequentially formed on the piezoelectric substrate in a part of the lead electrode. 4. The piezoelectric vibration element according to Application Example 2 or 3, wherein the piezoelectric vibration element is laminated.

  According to this configuration, the first layer, the second layer, the third layer, and the fourth layer are sequentially stacked in a part of the stacked portion of the lead electrode, and the strength and conductivity of the stacked portion are There is an effect that a piezoelectric vibration element which is sufficient and has a small CI value can be obtained.

  Application Example 6 In the piezoelectric vibration element according to Application Example 4 or 5, the material of the second layer and the fourth layer is gold.

  According to this configuration, the second layer and the fourth layer of a part of the laminated portion of the lead electrode use gold as a material, and are advantageous in terms of conductivity and aging. There is.

  Application Example 7 In the piezoelectric vibration element, the material of the first layer and the third layer is nickel or chrome, according to any one of application examples 4 to 6, wherein the material is nickel or chromium. It is a piezoelectric vibration element.

  According to this configuration, nickel or chromium is used as the material for the first layer and the third layer of a part of the laminated portion of the lead electrode, and the adhesion to the piezoelectric substrate and the attachment between the layers are increased. There is an advantage that it is excellent in wearability.

  Application Example 8 In the piezoelectric vibration element, the first support portion, the second support portion, and the third support portion in which the piezoelectric substrate is integrated with the vibration portion and is thicker than the thickness of the vibration portion. It is a piezoelectric vibration element as described in any one of the application examples 1 thru | or 7 characterized by having.

  According to this configuration, the support portion is thicker than the vibration portion, and the piezoelectric support element can be easily supported and fixed by the thick support portion. Further, when the excitation electrode and the lead electrode are set to appropriate film thicknesses, a piezoelectric vibration element having a small CI value of the main vibration and a large ratio of the CI value of the adjacent spurious to the CI value of the main vibration, that is, a large CI value ratio is obtained. There is an effect that it is. Furthermore, there is an advantage that the high-frequency piezoelectric vibration element using the fundamental wave is reduced in size.

  [Application Example 9] The piezoelectric vibration element according to Application Example 8, wherein at least one side of the vibration region is open.

  According to this configuration, since one side is open, the piezoelectric vibration element can be reduced in size and a piezoelectric vibration element having a small CI value can be obtained.

  Application Example 10 In the piezoelectric vibration element, the support portion includes the second support portion disposed along the one side, and a main surface of the second support portion is at least one of the vibration portions. The piezoelectric vibration element according to Application Example 9, wherein the piezoelectric vibration element is protruded from the main surface of the piezoelectric vibration element.

  According to this configuration, since the thickness of the second support portion is larger than the thickness of the vibration portion, by supporting and fixing the second support portion, the support of the vibration portion is robust and high-frequency is supported. There is an effect that a piezoelectric vibration element can be obtained.

  Application Example 11 In the piezoelectric vibration element, the thickness of the second support portion increases as the distance from one end edge connected to one side of the vibration region toward the other end increases. The piezoelectric vibration element according to any one of application examples 8 to 10, further comprising an inclined portion and a second support portion main body provided continuously with the other end edge of the inclined portion.

  According to this configuration, one (thinner side) of the second inclined portion is continuously provided in the vibration region, and the second support body is continuously provided on the other (thicker side) of the second inclined portion. In addition, since the stress due to holding the piezoelectric vibration element is almost absorbed by the second support body and the second inclined portion, a piezoelectric vibration element having a small CI value and a smooth cubic curve frequency temperature characteristic is obtained. There is an effect that it is.

  Application Example 12 In the piezoelectric vibration element, the piezoelectric substrate includes an orthogonal coordinate including an X axis as an electric axis that is a crystal axis of quartz, a Y axis as a mechanical axis, and a Z axis as an optical axis. Centering on the X axis of the system, the Z axis is inclined by a predetermined angle in the −Y direction of the Y axis as a Z ′ axis, and the Y axis is only in the + Z direction of the Z axis by the predetermined angle. Application examples 1 to 3, wherein the tilted axis is a quartz substrate having a Y′-axis, a plane parallel to the X-axis and the Z′-axis, and having a thickness parallel to the Y′-axis. 11 is a piezoelectric vibration element.

  According to this configuration, the piezoelectric substrate is formed as described above, so that the required specification can be configured with a more suitable cut angle, and has a frequency-temperature characteristic according to the specification, and the CI value is There is an effect that a high-frequency piezoelectric vibration element having a small CI value ratio can be obtained.

  Application Example 13 In the piezoelectric vibration element, the piezoelectric substrate includes a fourth support portion, and a protruding portion of the fourth support portion is on the negative side of the Z ′ axis. Any one of Application Examples 10 to 12 is a piezoelectric vibration element.

  According to this configuration, since the projecting portion is provided on the negative side of the Z ′ axis so as to be connected to the vibrating portion, there is an effect that a piezoelectric vibrating element that is robust against external vibration and impact can be obtained.

  [Application Example 14] In the piezoelectric vibration element according to any one of Application Examples 8 to 12, in which at least one slit is formed through the second support portion. It is.

  According to this configuration, by providing the slit in the second support portion, there is an effect of suppressing the spread of stress generated when the second support portion is fixed using a conductive adhesive or the like by the slit. .

  Application Example 15 A piezoelectric vibrator according to the present invention includes the piezoelectric vibration element according to any one of Application Examples 1 to 14 and a package that accommodates the piezoelectric vibration element. It is a vibrator.

  According to this configuration, since the excitation electrode and the lead electrode use the piezoelectric vibration element configured as described above, 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 small. That is, there is an effect that a piezoelectric vibrator having a large CI value ratio can be obtained. Furthermore, the size of the high-frequency piezoelectric vibrator is reduced, and the part that supports the piezoelectric vibration element is a single point. By providing a slit between the support portion and the vibration region, the stress caused by the conductive adhesive is reduced. Since it can be made small, 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.

  Application Example 16 An electronic device of the present invention is an electronic device characterized in that the package includes the piezoelectric vibration element according to any one of Application Examples 1 to 14 and an electronic component.

  According to this configuration, an electronic device (piezoelectric device) is configured by using the piezoelectric vibration element and the electronic component, so that the frequency reproducibility, the frequency temperature characteristic, and the aging characteristic are excellent, and a small and high frequency electronic device can be obtained. There is an effect that it is obtained.

  Application Example 17 In the electronic device according to Application Example 16, the electronic component is any one of a variable capacitance element, a thermistor, an inductor, and a capacitor.

  According to this configuration, an electronic device (piezoelectric device) is configured by using any one of the piezoelectric vibration element of the present invention and a variable capacitance element, a thermistor, an inductor, and a capacitor. However, there is an effect that it can be realized in a small size and at a low cost.

  Application Example 18 In the electronic device according to Application Example 16 or 17, the electronic device includes an oscillation circuit that excites the piezoelectric vibration element in a package.

  According to this configuration, an electronic device (piezoelectric device) is configured by using the piezoelectric vibration element in which the excitation electrode and the lead electrode are configured as described above and the oscillation circuit, so that a high-frequency piezoelectric oscillator and temperature compensation are achieved. Electronic devices such as piezoelectric piezoelectric oscillators and voltage controlled piezoelectric oscillators can be configured. Furthermore, when a voltage-controlled piezoelectric oscillator is configured, an electronic device having excellent frequency reproducibility and aging characteristics, a wide frequency variable range due to the use of a fundamental wave, and an excellent S / N ratio (signal-to-noise ratio) can be obtained. effective.

  Application Example 19 An electronic apparatus comprising the piezoelectric vibrator according to Application Example 15.

  According to this configuration, by using the piezoelectric vibrator of the present invention 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. .

BRIEF DESCRIPTION OF THE DRAWINGS 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 the figure which looked at PP cross section from + X-axis direction, (c) is QQ The figure which looked at the cross 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. FIG. 6 is a plan view showing a configuration of another modification of the piezoelectric vibration element 1. (A) is a top view which shows the structure of another modification of the piezoelectric vibration element 1, (b) is a top view which shows the structure of another modification. It is the schematic which showed the structure of the piezoelectric vibration element 2 of 2nd Example, (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 sectional view of the QQ cross section viewed from the + Z ′ direction. 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 perspective view of the piezoelectric vibrator 2 which concerns on 2nd Embodiment, (b) is QQ longitudinal cross-sectional view. (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 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 the sectional drawing.

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-sectional view of the QQ cross-section of −Z. 'It is a sectional view seen from the axial direction.
The piezoelectric vibration element 1 includes a piezoelectric substrate 10 having a vibrating portion 12 including a thin vibrating region, and thick support portions 14, 15, 16 connected to the vibrating region 12, and both main surfaces of the vibrating region 12 ( Excitation electrodes 25a and 25b formed so as to face the front and back surfaces, and leads formed by extending from the excitation electrodes 25a and 25b toward the pad electrodes 29a and 29b provided in the thick portions, respectively. Electrodes 27a and 27b. Here, the vibration region means a region where the vibration energy is confined, that is, the inside of the region where the vibration energy is almost zero, and the size of the vibration region in the X-axis direction and the size of the vibration region in the Z′-axis direction are As is well known, the ratio 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, thin and flat vibration region 12 and a thick support portion (support portion) 13 (14) integrated along three sides excluding one side of the vibration region 12. , 15, 16) and a structure in which one side of the vibration region 12 is exposed. The thick support portion 13 includes a first support portion 14 and a second support portion 15 that are arranged to face each other with the vibration region 12 interposed therebetween, and a base end portion between the first and second support portions 14 and 15. And a third support portion 16 that is continuously provided, and has a U-shaped structure in plan view.
That is, the thick support portion 13 includes the first support portion 14 and the second support portion 15 that are disposed to face each other with the vibration region 12 therebetween so as to open one side of the four sides of the vibration region 12. , And a third support portion 16 that connects between the base end portions of the first and second support portions 14 and 15. Here, “open” includes a case where one side is exposed and a case where a part is not exposed but completely exposed.

  Further, the first support portion 14 is connected to one side 12a of the thin flat plate-like vibration region 12, and from one edge (inner edge) connected to the one side 12a of the vibration region 12 to the other edge (outer side). A first inclined portion 14b having a thickness that gradually increases as the distance from the first inclined portion 14b increases, and a thick, quadrangular columnar first support portion main body 14a that is connected to the other edge of the first inclined portion 14b And. Similarly, the second support portion 15 is connected to one side 12b of the thin flat plate-like vibration region 12 and is connected from one end (inner end) to the other end ( A second inclined portion 15b whose thickness gradually increases as it is separated toward the outer edge, and a thick, quadrangular prism-shaped second support portion main body that is connected to the other end of the second inclined portion 15b. 15a.

Further, the third support portion 16 is connected to the one side 12c of the thin flat plate-like vibration region 12, and from one end edge (inner end edge) connected to the one side 12c of the vibration region 12 to the other end (outer side). A third inclined portion 16b having a thickness that gradually increases as it is separated toward the edge), and a thick, quadrangular columnar third support portion main body 16a that is connected to the other end edge of the third inclined portion 16b. And.
That is, the thin vibration region 12 constitutes the recessed portion 11 that is surrounded on the three sides by the first, second, and third support portions 14, 15, and 16 and that is open on the other side.
At least one stress relaxation slit 20 is formed through the second support portion 15. In the embodiment shown in FIG. 1, the slit 20 is formed in the plane of the second support portion main body 15a along the boundary between the second inclined portion 15b and the second support portion main body 15a.
The support body (14a, 15a, 16a) refers to a region having a constant thickness parallel to the Y ′ axis. One main surface of the vibration region 12 and one surface of each of the first, second, and third support portions 14, 15, and 16 are on the same plane, that is, XZ ′ of the coordinate axis shown in FIG. It is on a plane parallel to the plane, and this one main surface (the lower surface side of FIG. 1 (b)) is called a flat surface (flat surface), and the other main surface is the opposite surface (FIG. 1 (b)). The upper surface side) is called a concave surface. The recessed portion 11 side is the front surface, and the flat surface is the back surface.

  A piezoelectric material such as quartz belongs to the trigonal system and has crystal axes X, Y, and Z orthogonal to each other as shown in FIG. The X axis, the Y axis, and the Z axis are referred to as an electric axis, a mechanical axis, and an optical axis, respectively. The quartz substrate is a flat plate cut out from the quartz crystal along a plane obtained by rotating the XZ plane about the X axis by a predetermined angle θ. For example, in the case of an AT cut quartz substrate, 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 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. At this time, the size of the area of the excitation electrode 25b on the flat surface side (the back surface side in FIG. 1B) is larger than the size of the excitation electrode 25a on the concave surface side (the surface side in FIG. 1B). Set it large enough. 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 side (lower side), the plate back amount Δ (= (fs−fe) / fs, where fs is the cutoff frequency of the piezoelectric substrate and fe is the entire surface of the piezoelectric substrate. The frequency when the excitation electrode is attached to the 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 the range in which the ohmic cross does not increase, and the obliquely symmetric inharmonic mode (A0, A1,...) And the symmetric inharmonic mode (S1, S3). It is desirable not to set confinement mode. However, for example, if an extremely high frequency band piezoelectric vibration element such as the 490 MHz band is to be constructed, if the film is formed so as to avoid ohmic crossing of the electrode film thickness, it is unavoidable that the low-order inharmonic mode becomes a confinement mode. Absent.
The lead electrode 27a extended from the excitation electrode 25a formed on the front surface side passes through the third inclined portion 16b and the third support portion main body 16a from the vibration region 12, and the second support portion main body 15a. Is electrically connected to a pad electrode 29a formed on the upper surface of the substrate. In addition, 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 second support body 15a. And continuity connection.

The embodiment shown in FIG. 1A is an example of a lead-out structure of the lead electrodes 27a and 27b. Since the film thickness t2 of the leads 27a and 27b does not affect the vibration mode in the vibration region, it is preferable to increase the film thickness so that there is no ohmic cross and is suitable for wire bonding. That is, when the thickness of the excitation electrode 25a on the surface side (upper surface side) is t1, the lead electrodes 27a and 27b are configured to satisfy t1 <t2. An enlarged cross-sectional view of the film configuration of the portion indicated by UU of the excitation electrodes 25a and 25b is shown on the right side below FIG. A nickel film 25n is formed on the base, and a gold film 25g is stacked thereon. In addition, an enlarged cross-sectional view of the film configuration of the portion indicated by SS of the lead electrode 27a is shown in the lower center of FIG. A chromium film 27c is formed on the first layer, a gold film 27g on the second layer, a nickel film 27n on the third layer, and a gold film 27g on the fourth layer. This is because the second lead electrodes (lead electrodes 27a and 27b) having the film thickness t2 are formed first, and the excitation electrode 25a having the film thickness t1 is formed in the next step, so that the tip portions of the lead electrodes 27a and 27b are formed. And the first lead electrode (leading portion) extending from the excitation electrodes 25a and 25b are formed so as to overlap with each other, and has a four-layer configuration. That is, the second lead electrodes (lead electrodes 27a and 27b) are formed by sequentially forming a first layer (chromium film) 27c and a second layer (gold film) 27g on the piezoelectric substrate 12, and an excitation electrode thereon. A third layer (nickel film) 27n of the first lead electrode (leading portion) extending from 25a and a fourth layer (gold film) 27g are laminated.
In addition, an enlarged cross-sectional view of the film configuration of the portion indicated by RR of the lead electrode 27a is shown on the lower left side of FIG. A chromium film 27c is formed on the base, and a gold film 25g is stacked thereon.
The lead electrode 27a may pass through another support part. 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. Since the pad electrodes 29a and 29b are simultaneously formed in the same process as the lead electrodes 27a and 27b, the film thickness thereof is t2. 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 supported and fixed to the package by the conductive adhesive, first, the conductive adhesive is applied to the supported portion (pad electrode) 29a of the second supporting portion main body 15a, and this is applied to the package. Place it on the element mounting pad etc. and press it down a little. In order to cure the conductive adhesive, it is held at a high temperature for a predetermined time. In the high temperature state, the second support portion main body 15a and the package are both expanded, and the adhesive is also softened temporarily. Therefore, no stress is generated in the second support portion main body 15a. After the conductive adhesive is cured, when the second support portion main body 15a and the package are cooled and the temperature returns to room temperature (25 ° C.), the conductive adhesive, the package, and the second support portion main body 15a. Due to the difference from the respective linear expansion coefficients, the stress generated from the cured electroconductive adhesive spreads from the second support portion main body 15 a to the first and third support portions 14 and 16 and 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 disposed close to the boundary portion (joining portion) of the second support body 15a, a large area of the supported portion (pad electrode) 29a of the second support portion body 15a is ensured. The diameter of the conductive adhesive to be applied can be increased. On the other hand, when the slit 20 is disposed closer to the supported portion (pad electrode) 29a of the second support body 15a, 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 second support body 15a.

In order to obtain the stress (strain) distribution generated in the piezoelectric substrate 10, a simulation is generally performed using a finite element method. As the stress in the vibration region 12 is reduced, a piezoelectric vibration element having excellent frequency temperature characteristics, frequency reproducibility, and frequency aging characteristics can be obtained.
Examples of the conductive adhesive include silicon-based, epoxy-based, polyimide-based, and bismaleimide-based adhesives. A polyimide-based conductive adhesive is used in consideration of frequency aging due to degassing of the piezoelectric vibration element 1. . Since the polyimide-based conductive adhesive is hard, it is possible to reduce the magnitude of the stress generated by one support rather than two distant places. Therefore, a single-supported structure is used for the piezoelectric vibration element 1 for a voltage controlled piezoelectric oscillator (VCXO) of a high frequency band of 100 to 500 MHz, for example, 490 MHz. That is, the pad electrode 29a is mechanically fixed to the element mounting pad of the package using conductive bonding and is also electrically connected, and the other pad electrode 29b is electrically connected using the electrode terminal of the package and the bonding wire. Decided to connect to.

  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 occurs when the piezoelectric substrate 10 is fixed and connected with a conductive adhesive or the like. As is well known, the frequency when force is applied to both ends along the X-axis direction of the AT-cut quartz substrate is known. Comparing the circumferential change with the frequency circumferential change when the same force is applied to both ends along the Z′-axis direction, the frequency change is smaller when the force 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.

A feature of the present invention is the configuration of the excitation electrodes 25a and 25b, the lead electrodes 27a and 27b, and the pad electrodes 29a and 29b. FIG. 3A is a plan view showing the configuration of the lead electrodes 27 a and 27 b and the pad electrodes 29 a and 29 b formed on the piezoelectric substrate 10. The lead electrode 27 a extends from the edge of the excitation electrode 25 a on the surface, passes through the surface of the third support portion 16, and continues to the pad electrode 29 a provided on the center surface of the second support portion 15. 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 second support portion 15 via the end portion of the back surface. It is formed as follows. 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. As shown on the left side of the enlarged view of the RR cross section of a part 27aA of the lead electrode 27a, a chromium thin film 27c is used as an underlayer on the surface side (upper surface side) of the second support body 15a, and a gold film is formed thereon. The lead electrode 27a is formed by laminating the thin film 27g. 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 second support portion 15 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). As shown in the lower part of the enlarged view of the TT cross section of a part 29aA of the pad electrode 29a, a chromium thin film 29c is used as a base on the surface side (upper surface side) of the second support body 15a, and a gold film is formed thereon. A thin film 29g is laminated to form a pad electrode 29a. 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 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 and the pad electrodes 29a and 29b formed in the previous step. It is. An excitation electrode 25a is formed on the front surface, and an excitation electrode 25b sufficiently larger than the excitation electrode 25a is formed on the back surface.
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 27c of the lead electrode extending from the end. A portion 27c 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. . 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. When 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, there is a risk of thin film ohmic crossing due to the thin gold (Au) film of the lead electrodes 27a and 27b. Further, if the pad electrodes 29a and 29b are formed of a 70-thick nickel (Ni) thin film as the first layer and a 600-thick gold (Au) thin film as the second layer, the bonding strength is insufficient when wire bonding is performed. .

  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, and there is a concern that the CI of the main vibration increases. Also, the pad electrodes 29a and 29b formed of a 70-thick nickel (Ni) thin film on the first layer and a 600-thick gold (Au) thin film on the second layer have insufficient bonding strength.

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 film thickness of each electrode thin film are changed to the function of each thin film. We decided to set it to be optimal. That is, for the excitation electrodes 25a and 25b, for example, the electrode film thickness is set as thin as 70 mm nickel and 600 mm gold so that the main vibration is in the confinement mode and the adjacent in-harmonic mode is in the propagation mode (unconfined mode) as much as possible. On the other hand, the lead electrodes 27a and 27b and the pad electrodes 29a and 29b were set to be thick with a chromium (Cr) film thickness of 100 mm and a gold (Au) film thickness of 2000 mm to reduce the film resistance of the thin lead electrode.
That is, the excitation electrodes 25a and 25b are composed of 70 Å nickel (Ni) in the first layer and 600 金 gold (Au) in the second layer, and the lead electrode portion 27c extending from the excitation electrode 25a and the lead. A portion of the lead electrode 27b extending from the electrode 27a and the excitation electrode 25b and a portion where the lead electrode 27b overlaps in a part of the region is chromium (Cr) having a thickness of 100 mm in the first layer and a thickness of 2000 mm in the second layer. The structure is a four-layer structure in which a gold (Au) film having a thickness of 70 mm and a gold film having a film thickness of 600 mm are formed as a fourth layer. Also in this case, a structure in which a thin film of another metal is sandwiched between chromium (Cr) and gold (Au) or between nickel (Ni) and gold (Au) may be used.
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 made of a laminated film of chromium (Cr) and gold (Au) having a required thickness in consideration of the thin film ohmic cross and bonding strength. Using.
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 excitation electrode 25a. Note that the excitation electrode 25b on the back side may also be a sufficiently large circle.
In the embodiment shown in FIG. 5, the excitation electrode 25a on the front surface side is an ellipse, and the excitation electrode 25b on the back surface side is a quadrangle sufficiently larger than the excitation electrode 25a. 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 a cut surface obtained by cutting the displacement distribution along a plane parallel to the XZ ′ plane is elliptical. 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 plan view showing the configuration of a modification of the piezoelectric vibration element 1 shown in FIG. The modification of FIG. 6 differs from the piezoelectric vibration element 1 shown in FIG. 1 in the position where the stress relaxation slit 20 is provided. In this example, the slit 20 is formed in the second inclined portion 15 b that is separated from the edge of the one side 12 b of the thin vibration region 12. Rather than forming the slit 20 in the second inclined portion 15b so that one edge of the slit 20 is in contact with the one side 12b along the one side 12b of the vibration region 12, both end edges of the second inclined portion 15b are formed. The slit 20 is provided further apart. That is, in the second inclined portion 15b, an extremely thin inclined portion 15bb connected to the edge of the one side 12b of the vibration region 12 is left. In other words, an extremely fine inclined portion 15bb is formed between the side 12a and the slit 20.

FIGS. 7A and 7B are schematic plan views showing configurations of other modified examples of the piezoelectric vibration element 1 shown in FIG. The modification of FIG. 7A is different from the piezoelectric vibration element 1 shown in FIG. 1 in that the first slit 20a is provided in the surface of the second support portion main body 15a and the second inclined portion 15b. The second slit 20b is formed in the plane, and two stress relaxation slits are provided. The first slit 20a and the second slit 20b are not juxtaposed in the X-axis direction as shown in the plan view of FIG. 7A, but are arranged in steps so as to be separated from each other in the Z′-axis direction. May be. The provision of the two slits 20 a and 20 b can prevent the stress caused by the conductive adhesive from spreading to the vibration region 12.
The configuration of the modification shown in FIG. 7B is a piezoelectric vibration element that has the effect of the slit 20 shown in FIG. 1 and FIG. 6, respectively. The slit 20 includes the second inclined portion 15b. The second support main body 15a is straddled.

FIG. 8 is a schematic diagram illustrating the configuration of the piezoelectric vibration element 2 according to the second embodiment. FIG. 8A is a plan view of the piezoelectric vibration element 2, FIG. 8B is a cross-sectional view of the PP cross section viewed from the + X axis direction, and FIG. It is sectional drawing seen from the axial direction, The figure (d) is sectional drawing which looked at the QQ cross section from + Z 'axial direction. With reference to FIG. 1, parts having the same functions as those in FIG.
The piezoelectric vibration element 2 includes a thin vibration region 12, a piezoelectric substrate 10 having a thick support portion 13 connected to the vibration region 12, and excitation electrodes formed to face both main surfaces of the vibration region 12. 25a, 25b, lead electrodes 27a, 27b formed to extend from the excitation electrodes 25a, 25b to the thick portion support portion 13, respectively, and pad electrodes 29a, 29b connected to the terminal ends of the lead electrodes 27a, 27b, It has.

The piezoelectric substrate 10 includes a rectangular and thin flat plate-like vibration region 12 and a square annular thick support portion 13 integrated along four sides of the periphery of the vibration region 12.
The thick support portion 13 includes a first support portion 14 and a second support portion 15 that protrude from both main surfaces along two opposite sides 12a and 12b of the main surface of the vibration region 12, respectively. A third support portion 16 that protrudes from the first main surface side (front surface side) of the vibration region 12 so as to be connected between both end portions of the first and second support portions 14 and 15, and the third support portion. And a fourth support portion 17 projecting along the other main surface side (rear surface side) of one side 12d of the vibration region 12 facing the support portion 16.

The first support portion 14 is connected to one side 12a of the thin flat plate-like vibration region 12 and protrudes from both main surfaces. A first inclined portion 14b having a thickness that gradually increases as it is separated from one side 12a of the vibration region 12, a first support portion main body 14a having a thick quadrangular column shape that is connected to the other end edge of the first inclined portion 14b, It has. That is, as shown in FIG. 8D, the first support portion 14 is formed so as to project from both main surface sides of the vibration region 12.
Similarly, the second support portion 15 is connected to one side 12b of the thin flat plate-like vibration region 12 and protrudes from both main surfaces. A second inclined portion 15b having a thickness that gradually increases as it is separated from one side 12b of the vibration region 12, a second support portion main body 15a having a thick quadrangular column shape that is connected to the other end of the second inclined portion 15b, It has.

The third support portion 16 is provided on the surface side of the thin flat plate-like vibration region 12 so as to be connected to the one side 12c, and the third inclined portion 16b whose thickness gradually increases as the distance from the one side 12c increases. And a thick quadrangular columnar third support portion main body 16a provided continuously with the other end edge of the three inclined portions 16b. That is, the third support portion 16 is formed so as to protrude from one main surface side (surface side) of the vibration region 12.
Further, the fourth support portion 17 is connected to the one side 12d of the vibration region 12 so as to face the third support portion 16 on the back side of the thin vibration region 12, and from the one side 12d of the vibration region 12 A fourth inclined portion 17b having a thickness that gradually increases as it is separated from each other, and a fourth support portion main body 17a having a thick quadrangular prism shape that is connected to the other end edge of the fourth inclined portion 17b are provided.
The third support portion 16 and the fourth support portion 17 have a point-symmetric relationship with respect to the midpoint of the vibration region 12, and the first, second, third, and fourth support portions 14, 15, 16 are provided. And 17 are configured such that their end portions are connected to form a square annular shape, and the vibration region 12 is held in the center thereof.
The support body (the first support body 14a to the fourth support body 17a) refers to a region having a constant thickness parallel to the Y ′ axis.

The thin vibration region 12 is surrounded by first, second, third, and fourth support portions 14, 15, 16, and 17 on the four sides of the periphery. That is, etching is performed from both front and back sides of a rectangular flat plate-shaped piezoelectric substrate, two concave portions facing both main surfaces are formed, and unnecessary portions are removed to form a thin vibration region 12 for miniaturization. ing.
Further, in the piezoelectric substrate 10, at least one stress relaxation slit 20 is formed through the second support portion 15. In the embodiment shown in FIG. 8, the slit 20 is formed in the plane of the second support portion main body 16a along the boundary portion (connecting portion) between the second inclined portion 16b and the second support portion main body 16a. Has been. Moreover, since the example which forms the slit for stress relaxation in the site | part similar to embodiment of FIG. 6, FIG. 7 is the same, description is abbreviate | omitted.
The surfaces of the first and second support bodies 14a and 15a and the surface of the third support body 16a are on the same plane, and the back surfaces of the first and second support bodies 14a and 15a. And the back surface of the 4th support main body 1a exists on the same plane.

The configuration of the excitation electrodes 25a and 25b, the lead electrodes 27a and 27b, and the pad electrodes 29a and 29b of the piezoelectric vibration element 2 shown in FIG. 8 is the same as that of the piezoelectric vibration element 1 shown in FIG. That is, 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 film thickness of each thin film are optimized for the function of each thin film. Is set to The lead electrodes 27a and 27b and the pad electrodes 29a and 29b are composed of 100 ク ロ ム chromium (Cr) in the first layer and 2000 金 gold (Au) in the second layer.
That is, the excitation electrodes 25a and 25b are composed of 70 Å nickel (Ni) in the first layer and 600 金 gold (Au) in the second layer, and the lead electrode portion 27c extending from the excitation electrode 25a and the lead. A portion of the lead electrode 27b extending from the electrode 27a and the excitation electrode 25b and a portion where the lead electrode 27b overlaps in a part of the region is chromium (Cr) having a thickness of 100 mm in the first layer and a thickness of 2000 mm in the second layer. The structure is a four-layer structure in which a gold (Au) film having a thickness of 70 mm and a gold film having a film thickness of 600 mm are formed as a fourth layer. Also in this case, a structure in which a thin film of another metal is sandwiched between chromium (Cr) and gold (Au) or between nickel (Ni) and gold (Au) may be used.
Also in this case, a structure in which a thin film of another metal is sandwiched between chromium (Cr) and gold (Au) or between nickel (Ni) and gold (Au) may be used.
Further, the shape of the excitation electrodes 25a and 25b may be the same as that of the piezoelectric vibration element 1 in FIGS. 4 and 5, and the stress relaxation slits are also in the same positions as in FIGS. At least one of them may be formed.

By appropriately setting the plate back (frequency reduction amount) of the excitation electrode 25a and setting the film thickness of the lead electrodes 27a and 27b so as to reduce ohmic cross, a lead electrode that can withstand wire bonding can be obtained. There is an effect.
In addition, the first lead electrode having the same thickness as the excitation electrode 25a having the film thickness t1 is set to an appropriate plate back amount, and the film thickness t2 of the lead electrodes 27a and 27b is set to a film thickness having no ohmic cross. By being set, the CI value of the piezoelectric vibration element is reduced.
In addition, the first lead electrode (lead) and the second lead electrode 27a are partially laminated so that there is no conduction failure between the excitation electrode 25a and the lead electrode 27a, and the CI value can be reduced. In addition, there is an effect that a piezoelectric vibration element with less spurious can be obtained.
Further, in a part of the laminated portion of the lead electrode 27a, the first layer and the second layer are sequentially laminated by the lead electrode 27a, and then the third layer and the fourth layer are sequentially laminated by the excitation electrode 25a. Therefore, the conductivity of the laminated part is sufficient. In addition, the adhesive force between the lead electrode and the piezoelectric substrate is increased, and there is an effect that it can sufficiently withstand wire bonding.
In addition, the first layer, the second layer, the third layer, and the fourth layer are sequentially stacked in a part of the stacked portion of the lead electrode 27a, and the strength and conductivity of the stacked portion are sufficient. There is an effect that a piezoelectric vibration element having a small CI value can be obtained. Nickel or chromium is used as the material for the first layer and the third layer of a part of the laminated portion of the lead electrode 27a, and is excellent in adhesion to the piezoelectric substrate and adhesion between the layers. There is an advantage that.
Further, gold is used as a material for the second layer and the fourth layer of a part of the laminated portion of the lead electrode 27a, and there is an advantage that it is extremely excellent in terms of conductivity and aging.

The first to fourth support parts 14 to 17 (FIG. 8) are thicker than the vibration part, and the thick support part has an effect that the piezoelectric vibration element can be easily supported and fixed. Further, when the excitation electrodes 25a and 25b and the lead electrodes 27a and 27b are set to appropriate film thicknesses, 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 There is an effect that a large piezoelectric vibration element can be obtained. Furthermore, there is an advantage that the high-frequency piezoelectric vibration element using the fundamental wave is reduced in size. Further, as shown in FIG. 1, since one side is open, the piezoelectric vibration element can be reduced in size and a piezoelectric vibration element having a small CI value can be obtained.
Further, as shown in FIG. 1, since the thickness of the second support portion 15 is thicker than the thickness of the vibration portion 12, the support of the vibration portion 12 is robust by supporting and fixing the second support portion 15. In addition, there is an effect that a high-frequency piezoelectric vibration element can be obtained. Further, one of the second inclined portions 15b (thinner one) is connected to the vibration region 12, and the second support body 15a is connected to the other (thicker one) of the second inclined portions 15b. In addition, since the stress due to the holding of the piezoelectric vibration element is substantially absorbed by the second support body 15a and the second inclined portion 15b, the piezoelectric vibration element has a small CI value and a smooth frequency curve frequency temperature characteristic. Is effective.
Further, as shown in FIG. 2, by forming the piezoelectric substrate, it is possible to configure the required specification with a more suitable cut angle, and it has a frequency temperature characteristic according to the specification, and the CI value is small. There is an effect that a high-frequency piezoelectric vibration element having a large CI value ratio can be obtained.
Further, as shown in FIG. 8, since the projecting portion 17 is provided on the negative side of the Z ′ axis so as to be connected to the vibrating portion 12, an effect of obtaining a piezoelectric vibrating element that is robust against external vibration and impact can be obtained. is there.
Moreover, by providing the slit 20 in the second support portion 15, there is an effect that the slit 20 suppresses the spread of stress generated when the second support portion 15 is fixed using a conductive adhesive or the like. .

A method for manufacturing the piezoelectric substrate 10 constituting the piezoelectric vibration element 2 according to the second embodiment shown in FIG. 8 will be described with reference to the manufacturing process diagram shown in FIG. FIG. 9 is a manufacturing process diagram relating to the formation of the recesses 11 and 11 ′ on both surfaces of the piezoelectric substrate 10 and the formation of the outer shape and slits (not shown) 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 polished on both sides, for example, 80 μm, 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 front and back surfaces using a mixed liquid 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 slightly shifted on both main surfaces to form the recessed portions 11 and 11 ′, and the quartz wafers 10W 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 crystal wafer 10W is in a state where the piezoelectric substrates 10 are connected by supporting strips and are regularly arranged in a lattice shape. The feature of the present invention is that, as shown in step S <b> 10, recesses 11 and 11 ′ are formed on both principal surfaces of the piezoelectric substrate 10 to form a vibration region 12, and third and fourth connected to the vibration region 12. The support portions 16 and 17 are formed point-symmetrically with respect to the center of the piezoelectric substrate 10.
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 adjusting the thickness of the vibration region 12 of each piezoelectric substrate 10 formed on the quartz wafer 10W within a predetermined thickness range, the excitation electrodes 25a and 25b and the lead electrode 27a are applied to each piezoelectric substrate 10. , 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 lead electrode and pad electrode portions are left as they are.

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. In the drawing of step S15, the metal film and the resist film (M + R) are represented by the symbol C in order to avoid complication. Further, a resist is applied on the metal film M to form a resist film R. Then, the resist film R corresponding to the excitation electrodes 25a and 25b is exposed using the excitation electrode mask pattern Mk. 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 reference C is returned to (M + R), and when the unnecessary resist film R remaining on the metal film M is peeled off, (Ni + Au) excitation electrodes 25a, 25b and ( 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 crystal wafer 10W, the divided piezoelectric vibration element 2 is obtained.
The piezoelectric vibration element 2 according to the second embodiment of the present invention is characterized in that etching is advanced from both main surfaces of the piezoelectric substrate 10 to form concave portions 11 and 11 ′ opposite to both main surfaces, respectively, and the vibration region 12. Therefore, the processing time required for etching can be halved. In addition, as shown in FIG. 11D, one of the features is that the piezoelectric substrate can be miniaturized by removing both the outer sides of the two broken lines indicated by Zc1 and Zc2 by etching. Since etching proceeds from both main surfaces of the piezoelectric substrate 10, the depth dug by etching from the respective main surfaces of the piezoelectric substrate 10 can be reduced, so that regions in which individual pieces in the wafer are laid out at the time of manufacture It was possible to reduce the variation in thickness of the vibrating portion that was thin between the wafers or between the wafers. The reason for this is that if the piezoelectric substrate 10 is immersed in the etching solution for a long time, the concentration of the solution in the etching solution may be different, and the etching of the piezoelectric substrate 10 is caused by the concentration difference. There is a possibility that the uniformity of the vibration may not be maintained, and the thickness of the vibrating part may vary between regions where the individual pieces in the wafer are laid out or between wafers, making it difficult to control the thickness. Because there is.

Further, as shown in FIGS. 11C and 11D, a manufacturing method was established on the premise that both end portions in the drawing which are unnecessary as a vibration region are deleted. Compared to the structure with the conventional thick portion described as the prior art, the size of the piezoelectric vibration element 1 can be reduced while ensuring the area of the flat ultrathin portion that becomes the vibration region. .
Further, as described above, the frequency change when the force is applied to both ends in the X-axis direction of the AT-cut quartz substrate (the stress / strain caused by the mounting is described as the force), and the Z′-axis By comparing the frequency change when the same force is applied to both ends in the direction, the amount of frequency change when the force is applied to both ends in the Z′-axis direction can be reduced. Since the length in the direction is so-called X-long, which is longer than the length in the Z′-axis direction, a large area of the vibration part can be secured in the X-axis direction.
Moreover, since the thick support part is provided in at least one of the front and back with respect to the main surface of a vibration part over the perimeter of the vibration part of the piezoelectric vibration element 1 which concerns on this invention, vibration Since the end of the portion is not exposed to the outside, something is necessary for the piezoelectric vibration element 1 during the manufacture of the piezoelectric vibration element 1 or the process of mounting the piezoelectric vibration element 1 on a container and manufacturing the piezoelectric vibrator Also, from the viewpoint of reliability such as impact resistance of the piezoelectric vibration element 1 due to being hit or the like, the strength is maintained high, so that the reliability can be maintained high.

11 is a more detailed view of the piezoelectric vibration element 2 shown in FIG. 8, in which FIG. 11 (a) is a perspective view, and FIG. 11 (b) is a cut view of a QQ section in FIG. 1 (a). It is. As shown in FIG. 11B, in the outer shape of the piezoelectric vibration element 2, an inclined surface appears on the end surface intersecting the X axis. That is, the inclined surface 1 appears on the end surface on the −X axis side, and the inclined surface 2 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.
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.

1 and 3, the excitation electrodes 25a, 25, the lead electrodes 27a, 27b, and the pad electrodes 29a, 29b are made of different metal materials 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. Furthermore, the high-frequency piezoelectric vibration element using the fundamental wave is miniaturized, and by providing a slit between the support portion and the vibration region, it is possible to suppress the spread of stress due to adhesion and fixation, so that the frequency temperature characteristics, There is an effect that a piezoelectric vibration element excellent in CI temperature characteristics and frequency aging characteristics can be obtained.
1, 3, and 8, the excitation electrodes 25a and 25b are a laminated film of nickel and gold, and the lead electrodes 27a and 27b and the pad electrodes 29a and 29b are made of chromium and gold. Since it is formed of a laminated film, a piezoelectric vibration element having a small main vibration CI value and a large ratio of the CI value of adjacent spurious to the CI value of the main vibration, that is, a large CI value ratio, which can sufficiently withstand bonding can be obtained. There is an effect. Further, the high-frequency piezoelectric vibration element using the fundamental wave is reduced in size, and the vibration region is firmly supported, so that there is an effect that a piezoelectric vibration element that is resistant to vibration, impact, and the like can be obtained.

Since the piezoelectric substrate 10 is formed as shown in the cutting angle diagram of FIG. 2, the required specification can be configured with a more suitable cut angle, and has a frequency temperature characteristic according to the specification. There is an effect that a high-frequency piezoelectric vibration element having a small value and a large CI value ratio can be obtained.
In addition, by using a quartz AT-cut quartz substrate as the piezoelectric substrate, it is possible to utilize the experience and experience related to photolithography technology and etching technique, so that not only mass production of piezoelectric substrates is possible, but also high-precision piezoelectric substrates can be obtained. The yield of piezoelectric resonator elements having a small CI value and a large CI value ratio is greatly improved.

12A and 12B are diagrams showing the configuration of the piezoelectric vibrator 5 according to the embodiment of the present invention. FIG. 12A is a longitudinal sectional view, and FIG. 12B is a plan view in which a lid member is omitted. . The piezoelectric vibrator 5 includes, for example, the piezoelectric vibration element 2 (which may be the piezoelectric vibration element 1) illustrated in FIG. 8 and a package that accommodates the piezoelectric vibration element 2. 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. 12, 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 2. 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 second 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 2, 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 silicon-based adhesive, an epoxy-based adhesive, and a polyimide-based adhesive. In addition, degassing increases in the order of polyimide adhesive, epoxy adhesive, and silicon 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 2 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. 12B, since the piezoelectric vibration element 2 is supported / fixed to the package body 40 at one point (one point), it is possible to reduce the magnitude of the stress generated by the support fixing. It becomes.
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.

  In each of the piezoelectric vibration elements 1 and 2 shown in FIGS. 1 and 8, pad electrodes 29a and 29b are formed to face the upper and lower surfaces of the piezoelectric substrate 10, respectively. As shown in FIG. 12, when the piezoelectric vibration element 2 is accommodated in a package, the piezoelectric vibration element 2 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 2 is turned upside down and accommodated in the package and the larger excitation electrode 25b is placed on the upper surface, frequency fine adjustment of the piezoelectric vibrating element 1 is facilitated.

A piezoelectric vibration element formed by separating the pad electrodes 29a and 29b from each other may be configured. In this case as well, a piezoelectric vibrator can be configured similarly to the piezoelectric vibrator 5 described with reference to FIG. Moreover, you may comprise the piezoelectric vibration element which formed the pad electrodes 29a and 29b on the same surface at intervals. In this case, the piezoelectric vibration element has a structure in which conductive adhesive is applied to two places (two points) so as to achieve conduction, support and fixation. Although the structure is suitable for reducing the height, 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.

  As shown in the embodiment examples of FIGS. 2 and 8, 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, and the film thicknesses thereof are different. Since the piezoelectric vibration elements 1 and 2 configured to be 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, that is, the CI value ratio Large piezoelectric vibrator 2 can be obtained. Further, the high-frequency piezoelectric vibrator is reduced in size, and as shown in the embodiment of FIG. 12, the portion for supporting the piezoelectric vibration element is one point, and a slit is provided between the support portion and the vibration region. Since the stress caused by the conductive adhesive can be reduced, a piezoelectric vibrator having excellent frequency reproducibility, frequency temperature characteristics, CI temperature characteristics, and frequency aging characteristics can be obtained.

  FIG. 13 is a longitudinal sectional view showing an embodiment of the piezoelectric device 6 according to the present invention. The electronic device 6 is one of the piezoelectric vibration element 2 (which may be the piezoelectric vibration element 1) of the present invention and an electronic component, and houses the thermistor Th that is a temperature-sensitive element, the piezoelectric vibration element 2, and the thermistor Th. And a package. 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. A plurality of element mounting pads 47 are provided at the end of the inner bottom surface of the cavity 31, and each element mounting pad 47 is electrically connected to the plurality of mounting terminals 45 by an internal conductor 46. The conductive adhesive 30 is applied to the pad electrode 29 a of the piezoelectric vibration element 2, and this is reversed and placed on the element mounting pad 47. 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 2 and the thermistor Th are accommodated in the package 40a is configured as in the embodiment shown in FIG. 13, the thermistor Th as the temperature sensitive element is arranged very close to the piezoelectric vibration element 2. Therefore, there is an effect that a temperature change of the piezoelectric vibration element 2 can be quickly detected. 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. 14 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. 14 (a) is a longitudinal sectional view and FIG. 14 (b) is a lid member. FIG. The piezoelectric oscillator 7 includes a package main body 40b, a lid member 49, a piezoelectric vibration element 2, an IC component 51 on which an oscillation circuit for exciting the piezoelectric vibration element 2 is mounted, a variable capacitance element whose capacitance varies 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 2, 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 29a and the electrode terminal 48 of the package with the bonding wire BW, the part supporting the piezoelectric vibration element 2 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. 14, the piezoelectric vibration element 2, 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 2 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 vibrating element 2 from the IC component 51 and the electronic component 52 and hermetically seals the piezoelectric vibrating element 1 alone. Excellent frequency aging characteristics.

As shown in FIG. 14, by configuring a piezoelectric device (for example, a voltage controlled piezoelectric oscillator), the voltage controlled piezoelectric is excellent in frequency reproducibility, frequency temperature characteristics, and aging characteristics, and is small and has a high frequency (for example, 490 MHz band). There is an effect that an oscillator can be obtained. Further, since the piezoelectric device uses the piezoelectric vibration element 2 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, piezoelectric devices such as piezoelectric oscillators, temperature compensated piezoelectric oscillators, and voltage controlled piezoelectric oscillators can be configured as piezoelectric devices. Piezoelectric oscillators with excellent frequency reproducibility and aging characteristics, temperature compensation with excellent frequency temperature characteristics The piezoelectric oscillator has the effect of providing a voltage controlled piezoelectric oscillator having a stable frequency, a wide variable range, and a good S / N ratio (signal-to-noise ratio).

  FIG. 16 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. 16, 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. 17A is a piezoelectric substrate 10 having a thin portion having a vibration region 12 and a thick portion provided on the periphery of the thin portion and thicker than the thin portion. 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. 17B is a piezoelectric substrate 10 having 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 notches 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. 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 of FIG. 17C 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. 18 is characterized in that it takes the form of two-point support, that is, a mount portion F1 and a mount portion F2, with respect to the structure of FIG.
In FIGS. 17 and 18, inclined portions are shown on the inner walls of the support portions 14, 15, and 16 of the thick support portion 13, while the outer side wall surface of the thick support portion 13 Although the inclined surfaces as shown in FIG. 12 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. 17, FIG. 18 respond | corresponds with the site | part which the same code | symbol of said each embodiment shows.

[Modified Example 2]
Further, FIG. 19A is a plan view of the piezoelectric vibration element 2, and FIG. 19B is an enlarged plan view of the embodiment of the pad electrode 29a (mount portion F) of the piezoelectric vibration element 1, and 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.

  Although the present invention has been described by taking an inverted mesa type vibrator as an example, the present invention is not limited to this, and can be widely applied to a piezoelectric vibrator including an ultrathin flat piezoelectric substrate in a high frequency band of 100 to 500 MHz. Needless to say.

1, 2, 3, 4... Piezoelectric vibrating element 5, 5. Piezoelectric vibrator, 6, 7 ... Piezoelectric device, 8 ... Electronic equipment, 10 ... Piezoelectric substrate, 10W ... Quartz wafer, 11, 11 '. Vibration region, 12a, 12b, 12c, 12d ... one side of vibration region, 13 ... support portion, 14 ... first support portion, 14a ... first support portion main body, 14b ... first inclined portion, 15 ... second 15a ... second support part main body, 15b ... second inclined part, 15b '... extra fine piece, 16 ... third support part, 16a ... third support part main body, 16b ... third inclination 17, fourth support portion, 17 a, fourth support portion main body, 17 b, fourth inclined portion, 20, slit, 20 a, first slit, 20 b, second slit, 21, chamfered portion, 22 ... Notch, 25a, 25b ... Excitation electrode, 27a, 27b, 27c, 27g ... Electrode, 29a, 29b, 29c, 29g ... pad electrode, 30 ... conductive adhesive, 31 ... cavity, 32 ... recess, 33 ... pad for mounting electronic components, 40, 40a, 40b ... package body, 41 ... first , 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 Components, 52 electronic components, 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 (19)

A piezoelectric substrate having a vibration part including a vibration region;
A pair of excitation electrodes arranged to face the vibration region on the front and back sides;
A lead electrode electrically connected to the pair of excitation electrodes and provided to extend on the support part;
A piezoelectric vibration element having
The film thickness of the excitation electrode is t1,
When the film thickness of the lead electrode is t2,
t1 <t2
A piezoelectric vibration element characterized by satisfying The lead electrode is
A first lead electrode electrically connected to the excitation electrode and having a thickness of t1,
A second lead electrode provided on the support and having a film thickness of t2,
The piezoelectric vibration element according to claim 1, wherein the piezoelectric vibration elements are electrically connected to each other. The lead electrode is
3. The piezoelectric vibration element according to claim 1, wherein the first lead electrode and the second lead electrode are configured to overlap at least in a part of the region. The excitation electrode is formed by laminating a first layer and a second layer in order on the piezoelectric substrate,
4. The piezoelectric vibration element according to claim 1, wherein the lead electrode is formed by sequentially stacking a third layer and a fourth layer on the piezoelectric substrate. 5. The partial area is:
4. The piezoelectric vibration element according to claim 2, wherein the third layer, the fourth layer, the first layer, and the second layer are sequentially stacked on a piezoelectric substrate. 5.   6. The piezoelectric vibration element according to claim 4, wherein the material of the second layer and the fourth layer is gold.   7. The piezoelectric vibration element according to claim 4, wherein a material of the first layer and the third layer is nickel or chromium. The piezoelectric substrate is
The first support portion, the second support portion, and the third support portion that are integrated with the vibration portion and are thicker than the thickness of the vibration portion. The piezoelectric vibration element according to one item.   The piezoelectric vibration element according to claim 8, wherein at least one side of the vibration region is open. The support part is
A second support portion disposed along the one side;
10. The piezoelectric vibration element according to claim 9, wherein a main surface of the second support portion is protruded from at least one main surface of the vibration portion. The second support part is
A second inclined portion that increases in thickness as it is spaced from one end edge of the vibration region toward the other end;
A second support portion main body provided continuously with the other end edge of the inclined portion;
The piezoelectric vibration element according to claim 8, wherein the piezoelectric vibration element is provided. The piezoelectric substrate is
Centering on the X axis of the orthogonal coordinate system consisting of the X axis as the electrical axis that is the crystal axis of the crystal, the Y axis as the mechanical axis, and the Z axis as the optical axis,
An axis obtained by inclining the Z axis by a predetermined angle in the −Y direction of the Y axis is a Z ′ axis,
An axis obtained by inclining the Y axis by the predetermined angle in the + Z direction of the Z axis is a Y ′ axis,
It is composed of a plane parallel to the X axis and the Z ′ axis,
The piezoelectric vibration element according to claim 1, wherein the piezoelectric vibration element is a quartz crystal substrate having a thickness in a direction parallel to the Y ′ axis. The piezoelectric substrate is
Comprising a fourth support,
13. The piezoelectric vibration element according to claim 10, wherein the projecting portion of the fourth support portion is on the negative side of the Z ′ axis. In the second support part,
The piezoelectric vibration element according to claim 8, wherein at least one slit is formed so as to penetrate therethrough. The piezoelectric vibration element according to any one of claims 1 to 14,
A package containing the piezoelectric vibration element;
A piezoelectric vibrator characterized by comprising: The piezoelectric vibration element according to any one of claims 1 to 14,
An electronic device comprising an electronic component and a package.   The electronic device according to claim 16, wherein the electronic component is any one of a variable capacitance element, a thermistor, an inductor, and a capacitor.   18. The electronic device according to claim 16, wherein an oscillation circuit for exciting the piezoelectric vibration element is provided in a package.   An electronic apparatus comprising the piezoelectric vibrator according to claim 15.

Images