JP5136635B2 - Piezoelectric vibrator - Google Patents

Description

The present invention provides a piezoelectric vibrator using a strip-shaped piezoelectric substrate, wherein a plurality of grooves or holes are formed between an excitation main electrode at a central portion on both main surfaces of the piezoelectric substrate and an end portion in the longitudinal direction of the piezoelectric substrate, Alternatively, the present invention relates to a piezoelectric vibrator including a doped piezoelectric substrate.

In recent years, piezoelectric vibrators such as crystal vibrators have been widely used as reference frequency signal sources used in various electronic devices and transmission communication equipment. In particular, crystal resonators using AT-cut quartz substrates have extremely high frequency stability over a wide temperature range, and are excellent in aging characteristics, and are manufactured in large quantities at low cost due to advances in manufacturing technology. As a result, it is widely used in various communication devices centering on mobile communication.

AT-cut quartz resonators are often used in a thickness-shear vibration mode as the main vibration, and energy confinement crystal resonators are mainly used today and are widely used.

Here, the energy confinement type crystal resonator means that the frequency of the region without the excitation electrode of the quartz substrate is f'o, and the resonance frequency fo of the portion where the excitation electrode is present (mass load effect by adding the excitation electrode) Fo <f'o), the wave propagates freely in a part where the excitation electrode is present, but if the wave comes to a part where there is no excitation electrode (near the electrode end), the quartz substrate This is a crystal resonator that utilizes reflection that energy is confined by creating a standing wave directly under the electrode because reflection occurs on a plane parallel to the thickness direction, and vibration energy attenuates exponentially in the region where there is no excitation electrode. This is well known.

However, in the vicinity of the resonance frequency of the thickness-shear vibration mode, there is another thickness bending vibration (Thicknes vibration mode).
s Flexural Mode), Longitudinal Mode, Face Shear Mode
It is known that there is an unnecessary vibration mode. These unnecessary vibration modes depend on the outline size of the quartz substrate and adversely affect the desired resonance frequency obtained by the thickness-shear vibration, resulting in unwanted spurious and frequency and CI values with respect to temperature changes (crystal impedance = crystal Discontinuous fluctuation of the equivalent resistance of the resonator, so-called singular phenomenon (An
omalous Activity Dip) was a problem.

As one of the measures for suppressing the above problems, chamfering processing around the quartz substrate has been proposed and widely implemented. The structure of a quartz substrate that has been chamfered is generally called a bevel structure or a convex structure. FIG. 13A shows a single-side bevel (plano bevel).
FIG. 13B shows a double-sided bevel (bi-bevel) structure, FIG. 14A shows a single-sided convex (plano convex), and FIG. 14B shows a double-sided convex (bi-convex) structure. These crystal substrates have a structure in which the plate thickness is gradually reduced from the center of the crystal substrate toward the end in the longitudinal direction.

These chamfering processes are performed by a barrel polishing apparatus. The barrel polishing apparatus includes a piping method for rotating a cylindrical pipe, and a high-speed planetary turning method for rotating or rotating a cylindrical or spherical barrel tank. Put a quartz substrate and abrasive grains in these barrel polishing equipment, rotate the tank,
A quartz substrate pressed by its own weight and abrasive grains are brought into contact with each other, and the periphery of the quartz substrate is polished and chamfered by friction at that time.

By chamfering the outline of the quartz substrate as described above, it is possible to confine the energy of thickness-slip vibration that is the main vibration, while greatly reducing the energy of sub-vibration such as thickness bending, vertical, and outline slip. In other words, it becomes possible to confine the vibration energy in the thickness-shear vibration mode in the vicinity of the excitation electrode, and further suppress unnecessary spurious such as the contour vibration mode due to the crystal substrate dimensions, etc., and obtain a crystal resonator having good characteristics. be able to.

On the other hand, in order to improve the reproducibility of the effect of confining the energy of the main vibration and suppressing the secondary vibration mode that causes unnecessary spurious, it is possible to suppress the variation in the dimensional accuracy of the chamfering process and improve the accuracy. Processing needs to be maintained.

Today, electronic devices used for communication devices such as mobile phones are required to be miniaturized, and the development of miniaturization of crystal resonators is being promoted. The size of the quartz substrate is also reduced.

However, since the current barrel polishing apparatus performs polishing using its own weight, the amount of processing of the contour of the quartz substrate per unit time decreases with the miniaturization of the quartz substrate, thereby reducing the polishing time. There was a problem that the polishing efficiency was lowered due to the lengthening. Furthermore, since the abrasive grains are easily affected by humidity, and the abrasive grains are likely to be hardened with a slight humidity, there is a problem that it is difficult to control the accuracy with time by simple chamfering, and that variations are easily affected.
Therefore, stable quality maintenance by chamfering of the quartz substrate is extremely possible due to a combination of factors such as a decrease in polishing efficiency due to miniaturization of the quartz substrate and changes in polishing conditions (such as the effect of humidity on the abrasive grains). It has become difficult.

In other words, if the dimensional accuracy of the chamfered substrate of the quartz substrate decreases, variations in the resonance characteristics and frequency-temperature characteristics of the crystal unit and variations in the equivalent circuit constant value will occur. The decrease in the temperature was remarkable and was a major factor in the decrease in yield.
The object of the present invention has been made in view of the problems of the piezoelectric vibrator using the conventional piezoelectric substrate that requires chamfering as described above, and provides high-precision structural processing of the piezoelectric substrate necessary for energy confinement. It is another object of the present invention to provide a piezoelectric vibrator that can be realized with good reproducibility and has improved yield in mass production and a method for manufacturing the same.

In order to solve the above problems, a piezoelectric vibrator according to the present invention has the following configuration.
According to a first aspect of the present invention, the X-axis of an orthogonal coordinate system composed of an X-axis as an electric axis, a Y-axis as a mechanical axis, and a Z-axis as an optical axis, which is a crystal axis of quartz, An axis obtained by inclining the Z axis in the −Y direction of the Y axis as a center is referred to as a Z ′ axis, an axis obtained by inclining the Y axis in the + Z direction of the Z axis as a Y ′ axis, and the X axis and the Z axis. An AT-cut quartz substrate having a plane parallel to the 'axis and having a thickness in the direction parallel to the Y'-axis and having a thickness-shear vibration as a main vibration, and opposite main surfaces of the AT-cut quartz substrate. The AT cut quartz crystal substrate is a rectangular strip whose main surface is rectangular, and a plurality of etching electrodes are formed between the short sides of the strip and the excitation electrode. And a pair of side walls constituting the groove is formed by the anisotropy in the crystal axis direction of the crystal due to the anisotropy in the Y direction. Are inclined relative to the axis, the Y 'direction parallel depth to the axis of the groove depth Satoshi to the point where the pair of side walls intersect, the opening of the groove, for the excitation at a predetermined curvature It is curved toward the electrode side .
Second embodiment of the present invention, the plurality of grooves causes each with different parallel width to the long side of the strip of the opening, different depth in a direction parallel to the Y 'axis It is characterized by that.
According to a third aspect of the present invention , the length of the groove in the direction parallel to the short side of the strip is equal to or longer than the length of the side in the direction parallel to the short side of the strip of the excitation electrode. Features.
The fourth embodiment of the present invention is characterized in that the depth of the groove closest to the excitation electrode in the direction parallel to the Y ′ axis is shallower than the depth of the other grooves.
In the fifth embodiment of the present invention, the depth of the plurality of grooves in the direction parallel to the Y′-axis is shallower as the groove closer to the excitation electrode and deeper as the groove near the shorter side of the strip. Features.
According to a sixth aspect of the present invention, the X-axis of an orthogonal coordinate system comprising an X-axis as an electric axis, a Y-axis as a mechanical axis, and a Z-axis as an optical axis, which is a crystal axis of quartz, An axis obtained by inclining the Z axis in the −Y direction of the Y axis as a center is referred to as a Z ′ axis, an axis obtained by inclining the Y axis in the + Z direction of the Z axis as a Y ′ axis, and the X axis and the Z axis. An AT-cut quartz substrate having a plane parallel to the 'axis and having a thickness in the direction parallel to the Y'-axis and having a thickness-shear vibration as a main vibration, and opposite main surfaces of the AT-cut quartz substrate. The AT-cut quartz crystal substrate is a rectangular strip whose main surface is rectangular, and a plurality of grooves are provided between the short sides of the strip and the excitation electrode. The plurality of grooves extend from opposing long sides of the strip and are arranged so as to be interleaved with each other. Characterized in that the deeply than desired in some the Y 'depth of another groove in a direction parallel to the depth to the axis of the groove position between the short side of the strip.
According to a seventh aspect of the present invention, the X-axis of an orthogonal coordinate system comprising an X-axis as an electric axis, a Y-axis as a mechanical axis, and a Z-axis as an optical axis, which is a crystal axis of quartz, An axis obtained by inclining the Z axis in the −Y direction of the Y axis as a center is referred to as a Z ′ axis, an axis obtained by inclining the Y axis in the + Z direction of the Z axis as a Y ′ axis, and the X axis and the Z axis. An AT-cut quartz substrate having a plane parallel to the 'axis and having a thickness in the direction parallel to the Y'-axis and having a thickness-shear vibration as a main vibration, and opposite main surfaces of the AT-cut quartz substrate. The AT-cut quartz crystal substrate is a rectangular strip whose main surface is rectangular, and a plurality of grooves are provided between the short sides of the strip and the excitation electrode. The plurality of grooves extend from opposing long sides of the strip and are arranged so as to be interleaved with each other. Closest groove and the Y 'in the direction parallel to the axis the depth of the groove close to the next is characterized by shallower than the depth of the other groove.
According to an eighth aspect of the present invention, the plurality of grooves extend from a long side facing the strip to a vicinity of a center line parallel to the long side facing the strip and passing through a substantially central portion of the excitation electrode. It is characterized by extending.
According to a ninth aspect of the present invention, a notch is provided on a short side of the strip, a lead electrode is extended on the short side from the excitation electrode, a conductor film is provided on an inner wall of the notch, and the lead The electrode is electrically connected to the conductor film.
In a tenth aspect of the present invention, a through hole is provided between a short side of the strip and a groove closest to the short side of the plurality of grooves, and a lead electrode is formed in the through hole from the excitation electrode. And a conductor film is provided on the inner wall of the through hole, and the lead electrode is electrically connected to the conductor film.
In an eleventh aspect of the present invention, the first pair of sides constituting the strip is parallel to the X-axis, the second pair of sides is parallel to the Z′-axis, and the long side of the strip Is a side parallel to the X-axis, and a short side of the strip is a side parallel to the Z′-axis.
In a twelfth aspect of the present invention, the X-axis of an orthogonal coordinate system composed of an X-axis as an electric axis, a Y-axis as a mechanical axis, and a Z-axis as an optical axis, which is a crystal axis of quartz, An axis obtained by inclining the Z axis in the −Y direction of the Y axis as a center is referred to as a Z ′ axis, an axis obtained by inclining the Y axis in the + Z direction of the Z axis as a Y ′ axis, and the X axis and the Z axis. An AT-cut quartz substrate having a plane parallel to the 'axis and having a thickness in the direction parallel to the Y'-axis and having a thickness-shear vibration as a main vibration, and opposite main surfaces of the AT-cut quartz substrate. The AT cut quartz crystal substrate has a rectangular main surface with a rectangular main surface, and an additive is added between the short side of the strip and the excitation electrode. A doping layer is provided between the excitation electrode and the short side of the strip, and the X-axis is provided by the doping layer. Wherein the sandwiched vibration region right underneath the excitation electrodes countercurrent.
A thirteenth aspect of the present invention is characterized in that the additive is added using an ion implantation technique or a gas phase thermal diffusion technique.
In a fourteenth aspect of the present invention, the first pair of sides constituting the strip is parallel to the X-axis, the second pair of sides is parallel to the Z′-axis, and the long side of the strip Is a side parallel to the X-axis, and a short side of the strip is a side parallel to the Z′-axis.
[Application Example 1] In this application example, in a piezoelectric vibrator having a thickness shear vibration as a main vibration, an excitation electrode is formed at the center on both main surfaces of the piezoelectric substrate, and the propagation direction of the thickness shear vibration of the piezoelectric substrate is A piezoelectric vibrator characterized in that a plurality of grooves are provided between an end portion and the excitation electrode.

Application Example 2 In this application example, the piezoelectric vibrator has a strip shape, and the plurality of grooves are provided at a desired angle with respect to a line orthogonal to the long side of the piezoelectric substrate. A piezoelectric vibrator characterized by the following.

Application Example 3 In this application example, the piezoelectric vibrator has a strip shape, the plurality of grooves are inclined at a desired angle with respect to a line orthogonal to the long side of the piezoelectric substrate, and the piezoelectric substrate The piezoelectric vibrator is provided symmetrically with respect to a line parallel to a long side and passing through a substantially central portion of the excitation electrode.

Application Example 4 This application example is a piezoelectric vibrator characterized in that the plurality of grooves extend from the opposing long sides of the piezoelectric substrate and are arranged so as to be interleaved with each other.

Application Example 5 In this application example, the plurality of grooves extend from the long side of the piezoelectric substrate to the vicinity of a line that is parallel to the long side of the piezoelectric substrate and passes through a substantially central portion of the excitation electrode. A piezoelectric vibrator characterized by the following.

Application Example 6 The application example is a piezoelectric vibrator in which the groove is curved toward the excitation electrode side with a predetermined curvature.

Application Example 7 In this application example, the length of the groove is equal to or longer than the length of the excitation electrode side.

[Application Example 8] This application example is located on both sides of the excitation electrode, and the depth of the pair of grooves closest to the electrode in the thickness direction of the piezoelectric substrate is shallower than the other grooves. This is a piezoelectric vibrator.

Application Example 9 This application example is characterized in that the depth in the piezoelectric substrate thickness direction of the plurality of grooves is shallower as it is closer to the excitation electrode and deeper as it is closer to the longitudinal end portion of the piezoelectric substrate. It is a piezoelectric vibrator.

[Application Example 10] In this application example, the depth in the piezoelectric substrate thickness direction of the groove at a desired position between the excitation electrode and the longitudinal end portion of the piezoelectric substrate is made deeper than the depths of the other grooves. A piezoelectric vibrator characterized by the following.

[Application Example 11] In this application example, the depth in the piezoelectric substrate thickness direction of the pair of grooves that are located on both sides of the excitation electrode and are closest to the electrode and the pair of grooves that are next to each other is different. The piezoelectric vibrator is characterized by being shallower than the depth of the groove.

Application Example 12 In this application example, a pair of adjacent grooves at a desired position between the excitation electrode and the longitudinal end portion of the piezoelectric substrate, and the pair of grooves include the excitation electrode. The piezoelectric vibrator is characterized in that the depth in the thickness direction of the piezoelectric substrate of another pair of adjacent grooves positioned opposite to each other is deeper than the depth of the other grooves.

[Application Example 13] In this application example, in a piezoelectric vibrator having thickness shear vibration as a main vibration, an excitation electrode is formed at the center on both main surfaces of the piezoelectric substrate, and the propagation direction of the thickness shear vibration of the piezoelectric substrate is A piezoelectric vibrator comprising a plurality of holes provided between an end portion and the excitation electrode.

Application Example 14 This application example is a piezoelectric vibrator in which the vibrator has a rectangular shape, and the plurality of holes are formed in a row in the short side direction of the piezoelectric substrate.

Application Example 15 This application example is characterized in that the vibrator has a rectangular shape, and the row of holes is inclined at a desired angle with respect to a line orthogonal to the long side of the piezoelectric substrate. It is a piezoelectric vibrator.

Application Example 16 In this application example, the vibrator has a rectangular shape, the row of holes is inclined at a desired angle with respect to a line orthogonal to the long side of the piezoelectric substrate, and the piezoelectric substrate length A piezoelectric vibrator characterized in that the piezoelectric vibrator is provided symmetrically with respect to a line parallel to a side direction and passing through a substantially central portion of the excitation electrode.

Application Example 17 This application example is a piezoelectric vibrator in which the plurality of rows extend from opposing long sides of the piezoelectric substrate and are arranged so as to be interleaved with each other.

[Application Example 18] In this application example, the plurality of rows extend from the long side of the piezoelectric substrate to the vicinity of a line parallel to the long side of the piezoelectric substrate and passing through the substantially central portion of the excitation electrode. A piezoelectric vibrator characterized by the following.

Application Example 19 The application example is a piezoelectric vibrator in which the row is curved toward the excitation electrode side with a desired curvature.

Application Example 20 This application example is a piezoelectric vibrator in which the holes are arranged in a staggered pattern.

[Application Example 21] In this application example, the length of the row is equal to or longer than the length of the excitation electrode.

[Application Example 22] This application example is a piezoelectric vibrator characterized in that the hole in the piezoelectric substrate thickness direction of the hole close to the excitation electrode is shallower than the other holes.

Application Example 23 In this application example, the depth in the piezoelectric substrate thickness direction of the plurality of holes at a desired position between the excitation electrode and the longitudinal end portion of the piezoelectric substrate is set deeper than the depths of the other holes. This is a piezoelectric vibrator characterized by the above.

Application Example 24 This application example is characterized in that the depth of the hole in the thickness direction of the piezoelectric substrate is shallower as it is closer to the excitation electrode and deeper as it is closer to the longitudinal end of the piezoelectric substrate. A child.

[Application Example 25] This application example is characterized in that the depth in the piezoelectric substrate thickness direction of the holes constituting the row close to the excitation electrode is shallower than the depths of the holes included in the other rows. It is a vibrator.

Application Example 26 In this application example, the depth of the holes constituting the row in the piezoelectric substrate thickness direction is shallower as the holes in the row closer to the excitation electrode, and the holes in the row closer to the end in the longitudinal direction of the piezoelectric substrate. The piezoelectric vibrator is characterized by being deepened.

[Application Example 27] In this application example, the depth in the piezoelectric substrate thickness direction of the holes constituting the row at a desired position between the excitation electrode and the longitudinal end of the piezoelectric substrate is constituted in another row. The piezoelectric vibrator is characterized by being deeper than the depth of the hole to be formed.

[Application Example 28] In this application example, the depth in the piezoelectric substrate thickness direction of a pair of rows closest to the excitation electrode and a pair of rows adjacent to the next row constitutes another row. The piezoelectric vibrator is characterized by being shallower than the depth of the hole to be formed.

[Application Example 29] In this application example, in a piezoelectric vibrator having thickness shear vibration as a main vibration, an excitation electrode is formed at the center on both main surfaces of the piezoelectric substrate, and the propagation direction of the thickness shear vibration of the piezoelectric substrate is The piezoelectric vibrator is characterized in that an additive is added between an end portion and the excitation electrode.

Application Example 30 This application example is a piezoelectric vibrator in which the additive is added using an ion implantation technique or a gas phase thermal diffusion technique.

[Application Example 31] In this application example , a plurality of grooves or grooves are formed on a single wafer between the excitation electrode of the piezoelectric vibrator and the longitudinal end portion of the piezoelectric vibrator piece. The step of forming holes or the step of adding additives, and on a single wafer, corresponding to each piezoelectric vibrator piece and located at or near the end of the piezoelectric vibrator piece. A step of forming a through hole in a portion, a step of forming a plurality of excitation electrodes and lead electrodes of piezoelectric vibrator pieces on a single wafer, a step of forming a conductor film in the through hole, A method of manufacturing a piezoelectric vibrator, comprising: dividing a single wafer into a plurality of piezoelectric vibrators.

[Application Example 32] This application example is a method of manufacturing a piezoelectric vibrator, wherein the step of forming the groove or hole and the step of forming the through hole are performed simultaneously.

Application Example 33 This application example is a method for manufacturing a piezoelectric vibrator, in which the step of forming the excitation electrode and the lead electrode and the step of forming a conductor film in the through hole are performed simultaneously.

It is a figure for demonstrating embodiment concerning this invention, Comprising: (a) is a perspective view of a piezoelectric vibrator, (b) is a perspective view which shows the state which mounted the piezoelectric vibrator in the package, (c). It is AA sectional drawing. It is a figure for demonstrating other embodiment which concerns on this invention, Comprising: (a) is a perspective view of a piezoelectric vibrator, (b) is a perspective view which shows the state which mounted the piezoelectric vibrator in the package, (c) ) Is an AA cross-sectional view. (A) And (b) is sectional drawing which shows the structure of the groove | channel formed between the electrode for excitation of the piezoelectric vibrator concerning this invention, and a piezoelectric substrate longitudinal direction edge part. (A) And (b) is sectional drawing for demonstrating the property of an etching of a piezoelectric substrate. (A) thru | or (f) is sectional drawing for demonstrating the method of forming a groove | channel using a photolithographic technique and an etching technique in a piezoelectric substrate. It is sectional drawing for demonstrating collective formation of the groove | channel and through-hole which concern on this invention. (A) thru | or (e) is a top view for demonstrating the groove pattern formed in the piezoelectric substrate based on this invention. (A) thru | or (g) is a top view for demonstrating the pattern by the hole formed in the piezoelectric substrate which concerns on this invention. (A) thru | or (c) is a figure for demonstrating the depth of the groove | channel or hole formed in the piezoelectric substrate which concerns on this invention. (A) And (b) is a figure for demonstrating the depth of the hole formed in the piezoelectric substrate which concerns on this invention at random. It is a figure for demonstrating other embodiment which concerns on this invention, Comprising: (a) is a perspective view of a piezoelectric vibrator, (b) is a perspective view which shows the state which mounted the piezoelectric vibrator in the package, (c) ) Is an AA cross-sectional view. (A) thru | or (e) is a figure for demonstrating the manufacturing process of the piezoelectric vibrator which concerns on this invention. (A) And (b) is sectional drawing which shows the conventional bevel structure. (A) And (b) is sectional drawing which shows the conventional convex structure.

Hereinafter, the present invention will be described in detail based on the illustrated embodiment.
1A and 1B are diagrams showing an AT-cut quartz crystal resonator as an example of a piezoelectric vibrator according to the present invention. FIG. 1A is a perspective view of the crystal resonator 1, and FIG. FIG. 1C is a cross-sectional view taken along the line AA of FIG.
In this quartz crystal resonator 1, an excitation electrode 3 and a lead electrode 4 are formed of conductive material films on both main surfaces of a strip-shaped AT-cut crystal substrate, and on the main surface of the AT-cut crystal substrate on the package opening side. The lead electrode 4 is formed on the inner wall of the recess 5 provided with a notch at the end of the substrate from which the lead electrode 4 extends.
And a conductor film 6 connected to the. The conductor film 6 is on the extension of the lead electrode 4 and reaches the opposite main surface. By making the recess 5 into the through hole 7, the upper lead electrode 4
Can extend to near the bottom surface.

Further, a plurality of grooves 9 are formed between the excitation electrode 3 and the AT cut quartz substrate longitudinal end portion in parallel to the excitation electrode side 8 parallel to the substrate longitudinal end portion. The depth of these grooves gradually increases from the excitation electrode toward the end in the substrate longitudinal direction.

The through hole 7 may be an embodiment as shown in FIG. FIG. 2 (a)
FIG. 3 is a perspective view of a crystal resonator 14, in which a hole-like through hole 11 is provided between an excitation electrode 10 and an end portion in the longitudinal direction of an AT cut crystal substrate, and a lead electrode 12 is connected from the excitation electrode 10 to the through hole 11. The conductor film 13 formed in the through hole 11 extending to the other surface and penetrating the other surface
Connected to. FIG. 2B is a perspective view showing a state in which the crystal resonator 14 is mounted in the package 15 body, and FIG. 2C is a cross-sectional view taken along the line AA.

If the hole-shaped through-holes 11 are provided in the vicinity of both ends of the quartz substrate, and the lead electrode on the lower surface side extends to the upper surface, the crystal resonator 14 is mounted in the vertical direction when mounted in the package 15 body. The workability is improved because the connection can be made regardless of which side faces downward. Note that the concave through holes 7 shown in FIG. 1 can be provided on both ends of the quartz substrate to eliminate the vertical direction of the quartz resonator.

When each lead electrode 4 is connected to the pad 16 formed on the step of the recessed portion formed in the package 2 of FIG. 1B, the lead electrode 4 formed on the lower surface of the crystal substrate is padded. 16 is connected with a conductive adhesive or solder (binder), and the upper lead electrode 4 is connected to the conductive film 6 in the through hole 7 and the other pad 17 with a conductive adhesive 1
8 is connected. Therefore, the operation of connecting the upper and lower lead electrodes 4 to the pads 16 and 17 can be completed by applying the conductive adhesive 18 once, so that productivity can be improved.

Here, the plurality of grooves formed on the AT-cut quartz substrate will be described in detail below. The quartz crystal resonator shown in FIG. 1 and FIG. 2 includes a plurality of crystal resonators at predetermined intervals between excitation electrodes arranged at the center of both main surfaces of a parallel plate quartz substrate and the longitudinal ends of the quartz substrate. The groove 9 is formed. The groove 9 is formed on the quartz substrate by using a photolithography technique and an etching technique, and has a structure in which the depth of the groove 9 is made deeper toward the end in the longitudinal direction of the substrate.

With the above-described structure, as shown in FIG. 3A, the quartz substrate 20 (shown by a solid line) becomes pseudo-equivalent to the quartz substrate of the vibe bevel structure 19 shown by the dotted line, and the quartz substrate 20 is connected to the end of the quartz substrate. Prevent leakage of vibration energy in the main vibration mode (here, thickness-shear vibration mode)
It is possible to suppress the secondary vibration mode that is a cause of the spurious and confine the vibration energy of the main vibration mode directly under the excitation electrode portion.

In addition, as shown in FIG. 3B, the depth of at least one groove 22 is made deeper than the depth of other grooves except for the groove 21 close to the excitation electrode 3 among the plurality of grooves. As shown by the dotted line 23, a structure in which a predetermined portion is narrowed down may be used. In this case, vibration energy can be confined at a deep groove. Further, with such a structure, it is possible to obtain an effect that it is possible to prevent the conductive adhesive or the like from flowing into the excitation electrode 3 in the groove 24 close to the longitudinal end of the quartz substrate.

Here, a means for forming a plurality of grooves having different depths by a batch process by a photolithography technique and an etching technique will be described in detail.
Since the quartz substrate has anisotropy in the crystal axis direction, when the groove is formed by etching as shown in FIG. 4 (a), the cross section of the groove in the X axis direction is observed. The inclination has the property of being θ1 and θ2 at the etching end point.

As shown in FIG. 4B, the inclination of the groove sidewall is determined by the protective film 2 formed by photolithography.
In the process of etching the portion of the opening width s to be etched that is not covered with 7, the inclination θ1
, Θ2 is formed, and etching proceeds in the depth (quartz substrate thickness) direction until the point C of the depth d is reached, that is, the inclination θ1 = tan ⁻¹ (CP / AP), θ2 = tan
^-1 is the end point of etching when the formation of the (CQ / BQ) side walls 25 and 26 is completed, and the etching does not proceed thereafter.

That is, the side wall formation time (etching end point time) varies depending on the size of the opening width s, and the depth d changes accordingly.

The applicant of the present application pays attention to this property and uses the fact that the depth d1 ≠ d2 when the opening width s1 ≠ s2 is set as shown in FIG. ,
A plurality of grooves having different depths can be collectively processed by using a photolithography technique and an etching technique, and a crystal resonator satisfying desired characteristics has been realized.

Hereinafter, a method for collectively forming grooves on a quartz substrate by a photolithography technique and an etching technique will be described with reference to FIG.
A quartz substrate 28 is prepared (FIG. 5A), and a protective film 29 is applied on both main surfaces (FIG. 5B).
). Exposure means 3 such as a mask having a hole 30 in a portion corresponding to the groove by photolithography.
1 is used to expose the protective film 29 (FIG. 5C), and development is performed to expose the quartz substrate only at a predetermined portion where a groove is to be formed (FIG. 5D). A plurality of grooves 32 are collectively formed by etching (FIG. 5E), and the protective film 29 is peeled off (FIG. 5F).

Here, by further applying the above-mentioned etching characteristics of the quartz substrate, the formation of the through hole for leading the lead electrode extending from the excitation electrode to the other surface can also be formed in a lump in the above-described groove forming process. Can be processed.
That is, as shown in FIG. 6, in consideration of the above-mentioned etching property of the quartz substrate, if the opening cross-sectional width t of the through hole 33 is s << t with respect to the groove width s, By simultaneously or alternately performing etching from the surface, the concave bottoms formed at the respective through-hole forming portions can be made to reach and penetrate each other at the center in the thickness direction of the quartz crystal substrate.

By the time the through hole 33 is formed, the groove 32 has a groove width s of the through hole opening width t.
Since the etching end point has already been reached with a predetermined inclination θs, the groove 32 and the through hole 33 can be processed by batch formation.
The relationship between the side wall inclination θs of the groove 32 and the side wall inclination θt of the through hole 33 is θs =
Needless to say, θt.

Next, another embodiment of the crystal resonator according to the present invention will be described with reference to FIGS.
FIG. 7A shows a groove 35 substantially parallel to the excitation electrode side 34, and the length of the groove 35 is changed to the electrode side 34.
FIG. 7B shows the pattern of the groove 38 formed by inclining a desired angle from the line orthogonal to the long side of the piezoelectric substrate toward the end portion 37 in the longitudinal direction of the piezoelectric substrate. Is inclined at a desired angle from a line orthogonal to the piezoelectric substrate long side 36 on the principal surface of the piezoelectric substrate toward the piezoelectric substrate longitudinal direction end portion 37 and parallel to the piezoelectric substrate longitudinal direction. The pattern of the groove 39 formed so as to be line symmetric with respect to the line passing through the center, FIG. 7D, extends from the opposing long side 36 of the piezoelectric substrate and extends to the longitudinal end portion 37 of the piezoelectric substrate. FIG. 7E shows a pattern of grooves 40 formed so as to be inclined at a desired angle toward each other, and an excitation electrode with a desired curvature from a desired portion on the bisector 38 of the short side of the piezoelectric substrate. It is the pattern of the groove | channel 41 which curved and formed in 3 side.

8A shows a pattern in which a plurality of holes 42 are provided between the piezoelectric substrate longitudinal direction end portion 37 and the excitation electrode 3, and the holes 42 are arranged in a row in the direction of the short side 37. FIG. b) is a pattern of row-shaped holes 43 formed by inclining at a desired angle from the line orthogonal to the piezoelectric substrate long side 36 toward the piezoelectric substrate longitudinal direction end portion 37, and FIG. 8C shows the piezoelectric substrate. With respect to a line that is inclined at a desired angle from a line orthogonal to the long side 36 toward the longitudinal end portion 37 of the piezoelectric substrate and is parallel to the longitudinal direction of the piezoelectric substrate and passes through the substantially central portion of the excitation electrode 3 The pattern of the array of holes 44 formed to be line symmetric, FIG. 8D, extends from the piezoelectric substrate long side 36 and is inclined at a desired angle toward the piezoelectric substrate longitudinal direction end portion 37. The pattern of the row-shaped holes 45 formed so as to be interleaved with each other, FIG. FIG. 8 (f) shows a pattern of a row of holes 46 formed by curving from the desired part on the bisector to the excitation electrode 3 side with a desired curvature, and FIG. FIG. 8G shows a pattern comprising a plurality of rows of holes 47 arranged in a staggered pattern between the electrodes 3, and the piezoelectric substrate longitudinal direction end 37 and the excitation electrode 3. This is a pattern composed of randomly formed holes 48.

Here, the depth of the groove or hole pattern formed on the AT-cut quartz substrate shown in the above-described modified embodiment is a structure in which the depth d1 of the groove or hole is constant as shown in FIG. , Fig. 9 (
As shown in FIG. 9B, the groove closest to the excitation electrode 3 or the depth d2 of the hole is shallower than the other grooves, or the excitation electrode 3 extends to the length of the quartz substrate as shown in FIG. A structure characterized by increasing the depth of the groove or hole toward the direction end 37 for a while (d3 <d4 <d5) is conceivable.

In the case of the holes 48 randomly provided in FIG. 8G, the depth of the holes 48 is as shown in FIG.
As a reference, the position 49 parallel to the end of the excitation electrode 3 in the direction of the short side 37 of the piezoelectric substrate,
As the distance x from the reference position 49 to the center of the hole approaches the longitudinal end of the piezoelectric substrate, the hole depth y may be set as shown in FIG.

Needless to say, the grooves or holes in the modified embodiment can be easily formed by using a photolithography technique and an etching technique on the quartz substrate.

Furthermore, when designing the energy confinement type vibrator, the selection of the groove or hole pattern and the setting of the groove or hole depth described above take into account the electrode film thickness and electrode dimensions of the excitation electrode required for energy confinement. What is necessary is just to set suitably based on a designer's design concept.

As described above, by using a photolithographic technique and an etching technique to process a groove or hole, the dimension or position of the groove or hole can be formed with high accuracy, and is a suitable processing means in mass production. Compared to chamfering of a small quartz substrate, the variation in processing can be extremely suppressed and the reproducibility is excellent. This variation can also be reduced.

Next, an additive (dopant) is added between the excitation electrode and the longitudinal end of the quartz substrate (dopi
ng), a method for confining energy in the vibration region immediately below the excitation electrode of the quartz substrate will be described below.

When a voltage is applied to the excitation electrode of an AT-cut quartz crystal unit, the vibration response includes a mixture of thick-slip vibration, which is the main vibration mode, and sub-vibration modes, such as contour-slip vibration, which cause spurious vibrations. In order to solve this problem, an excitation electrode is formed only on a part of the AT-cut quartz substrate, and between the excitation electrode and the longitudinal end of the substrate of the AT-cut quartz substrate, particularly in a small-sized quartz substrate. As described above, it is possible to realize an excellent crystal resonator in which the energy of the main vibration is confined immediately below the excitation electrode and the sub-vibration mode is suppressed by providing the groove or hole.

Further, as another embodiment according to the present invention, the applicant of the present application applies ion implantation (Ion Implantation) technology widely used in gas phase thermal diffusion technology and LSI manufacturing as shown in FIG. By forming the doping layer 50 between the excitation electrode 3 and the crystal substrate longitudinal direction end portion 37, a crystal resonator in which the energy of the main vibration is confined immediately below the excitation electrode and the sub vibration is suppressed can be realized. It came.

Here, the formation of the doping layer 50 using ion implantation will be described in detail below.
Ion implantation technology ionizes the additive and further accelerates it to produce LS as an ion beam.
This is a technique of striking into a substrate such as silicon used in I. When the energy of an ion beam is set to several hundred eV or more, ions irradiated to the substrate enter the surface layer and knock out atoms on the substrate surface into a vacuum. Sputtering phenomenon occurs. Furthermore, when the acceleration voltage is increased, ions enter deeper from the substrate surface in the substrate thickness direction.

Since the ion implanter is equipped with a mass spectrometer, only specific ion species can be selected and implanted, so different ion species can be selected for the same additive element depending on the implantation depth and amount. it can. Also, the amount of ions to be implanted can be accurately obtained by measuring the current flowing through the substrate as an ion current, and the implantation depth is determined by the ion species and the acceleration voltage, so that both the amount and depth of the additive can be controlled.
Therefore, the ion implantation method is a suitable method even in the mass production process of the crystal resonator.

In order to form the doping layer 50 between the excitation electrode 3 of the AT-cut quartz substrate and the end portion 37 in the longitudinal direction of the quartz substrate, first, a protective film is applied on the main surface of the AT-cut quartz substrate and photolithography technique is applied. The quartz substrate is exposed only in the doped layer formation region. Additives such as boron (B) and phosphorus (P) are appropriately selected, doping is performed by ion implantation to form a doping layer, and then the protective film is peeled off.

By performing the above-described processing, only the energy of the main vibration mode can be confined in the region directly under the excitation electrode by the doping layers 50 formed on both sides of the AT-cut quartz substrate directly under the excitation electrode as shown in FIG. Thus, the secondary vibration mode is suppressed, and the crystal resonator 51 having excellent vibration characteristics can be realized.

The crystal resonator 51 of FIG. 11 described above has a structure in which a wave is reflected near the boundary between the excitation electrode 3 and the doping layer 50 and desired energy is confined. However, as another embodiment,
In order to confine desired energy and obtain an effect equivalent to that of chamfering, the depth of the cross section of the doping layer forming region may be set to be equivalent to that in the case where grooves or holes are formed.
That is, by forming the doping layer forming region instead of the groove or hole, the same effect as that when the groove or hole is provided can be obtained.

Next, a method for manufacturing a crystal resonator according to the present invention as described above will be described with reference to FIG. Here, as an example, a method for manufacturing the AT-cut crystal resonator shown in FIG. 1 will be described. However, a manufacturing procedure for a crystal resonator having a crystal substrate having grooves or holes shown in FIG. This is in accordance with the manufacturing procedure of the crystal unit of FIG.

First, as shown in FIG. 12A, a single wafer 53 is prepared in a state where a plurality of parts to be pieces 52 are unseparated and connected. FIG. 12 (b) shows that a plurality of grooves 9 are etched and etched in a portion located between the excitation electrode 3 of each piece 52 on the single wafer 53 and the longitudinal end portion 37 of the piece. It is a process of forming by technique. FIG. 12C shows a process of forming the through hole 7 on a single wafer 53 and corresponding to each piece 52 and located at the end 37 of the piece 52. The position of the through hole 7 is a position determined in each piece. In this example, the position is along the boundary line 54 between the individual pieces 52.

FIG. 12D shows an excitation electrode 3 extending from the excitation electrode 3 by using vacuum deposition, sputtering film formation, photolithography technique or the like using means such as a mask having a shaped electrode. This is a step of forming the lead electrode 4 to be performed.
At the same time as or before or after this step, a conductor film 6 is formed at an appropriate position on the inner wall of the through hole to ensure conduction with one lead electrode 4.

FIG. 12E shows a process of dividing a single wafer 53 to which a plurality of pieces 52 are connected into pieces 52 using a cutting means such as a dicing saw. The AT-cut quartz crystal resonator 52 (1) shown in the drawing is completed by such a manufacturing procedure.

In the case of a crystal resonator having two hole-like through-holes positioned symmetrically as shown in FIG. 2, a plurality of pieces are connected to a position closer to the inside from the boundary line 54 of each piece of a single wafer. The through hole 11 will be formed. Further, the groove or hole forming step of FIG.
It is possible to simultaneously form the 2 (c) through hole by utilizing the etching property of the quartz substrate as described above, which contributes to shortening the lead time.

Further, in the case of the crystal resonator 51 in which the doping layer 50 is formed between the excitation electrode 3 and the crystal substrate longitudinal direction end 37 as shown in FIG. 11, the formation of the groove or hole of FIG. What is necessary is just to replace a process with the process of adding an additive with the ion implantation apparatus between the electrode 3 for excitation of a quartz substrate, and the quartz-crystal-substrate longitudinal direction edge part 37. FIG. Note that the step of forming the doping layer 50 may be performed before or after the through hole forming step of FIG.

As described above, the crystal resonator according to the present invention has a highly accurate variation in the groove or hole processing equivalent to the chamfering processing performed on the small crystal substrate used in today's small crystal resonator by the photolithography technique and the etching technique. In addition, since it can be realized with stable reproducibility, it is possible to provide an energy confinement crystal resonator that suppresses variations in various characteristics such as resonance characteristics and temperature characteristics and equivalent circuit constant values.

In addition, by forming a doping layer between the excitation electrode and the longitudinal end of the quartz substrate, it becomes possible to confine only the energy of the main vibration directly under the excitation electrode. It is possible to provide an energy confinement crystal resonator in which variations in various characteristics such as temperature characteristics and equivalent circuit constant values are suppressed.

Furthermore, the method for manufacturing a crystal resonator according to the present invention is extremely suitable for mass production, and there is no variation and the yield is high. Therefore, a manufacturing method with extremely high mass productivity can be provided.

The piezoelectric vibrator using the AT-cut quartz substrate and the manufacturing method thereof have been described as the embodiments of the present invention. However, the present invention is not limited to this, and other piezoelectric materials such as langasite (La ₃₎ It goes without saying that the present invention can also be applied to piezoelectric materials such as Ga ₅ SiO ₁₄ ), lithium tetraborate (Li ₂ B ₄ O ₇ ), and piezoelectric ceramic substrates.

(Effect of the invention)
Since the piezoelectric vibrator and the manufacturing method thereof according to the present invention are configured as described above, the following excellent effects can be obtained.
According to the invention of claim 1 to 28, a groove or hole machining equivalent to a chamfering process is formed on a small piezoelectric substrate used in a small piezoelectric vibrator of today by a photolithography technique and an etching technique.
It is possible to provide an energy confinement type piezoelectric vibrator that suppresses variations in various characteristics such as resonance characteristics and temperature characteristics and equivalent circuit constant values because it can be realized with high accuracy and no variation and stable reproducibility. Has an effect.

In the inventions of claims 29 and 30, since the doping layer is formed between the excitation electrode and the longitudinal end portion of the piezoelectric substrate, it is possible to confine only the energy of the main vibration directly under the excitation electrode. It is possible to provide an energy confinement type piezoelectric vibrator that suppresses variations in various characteristics such as characteristics and temperature characteristics and variations in equivalent circuit constant values.

The invention of claim 31 has an excellent effect that it is extremely suitable for mass production because the piezoelectric vibrator can be manufactured by batch processing without variation and with a high yield.

According to the thirty-second aspect of the present invention, since the step of forming a groove or hole and the step of forming a through hole can be performed at the same time, the lead time can be shortened.

In the invention of claim 33, since the step of forming the excitation electrode and the lead electrode and the step of forming the conductive film in the through hole can be performed at the same time, the lead time can be shortened, so that the production efficiency is improved. Has an excellent effect.

1 Piezoelectric vibrator, 2 package, 3 excitation electrode, 4 lead electrode, 5 notch,
6 conductive film, 7 through-hole, 8 excitation electrode side, 9 groove, 10 excitation electrode, 11
Through hole, 12 lead electrode, 13 conductive film, 14 piezoelectric vibrator, 15 package, 16 pad, 17 pad, 18 conductive adhesive, 19 dotted line, 20 piezoelectric substrate, 2
1 groove, 22 groove, 23 dotted line, 24 groove, 25 side wall, 26 side wall, 27 protective film, 2
8 piezoelectric substrate, 29 protective film, 30 holes, 31 mask, 32 grooves, 33 through holes, 34 excitation electrode sides, 35 grooves, 36 long sides, 37 short sides, 38 grooves, 39 grooves, 40
Groove, 41 Groove, 42 Hole, 43 Hole, 44 Hole, 45 Hole, 46 Hole, 47 Hole, 48
Hole, 49 reference line, 50 doping layer, 51 piezoelectric vibrator, 52 pieces, 53 single wafer, 54 border.

Claims (14)

Centering on the X axis of an orthogonal coordinate system consisting of an X axis as an electric axis, a Y axis as a mechanical axis, and a Z axis as an optical axis, which are crystal axes of quartz, the Z axis is the Y axis. The axis tilted in the -Y direction is the Z 'axis, the Y axis is tilted in the + Z direction of the Z axis as the Y' axis, and is composed of planes parallel to the X axis and the Z 'axis. An AT-cut quartz substrate having a thickness parallel to the Y′-axis and a thickness-shear vibration as a main vibration;
An excitation electrode provided on each of the main surfaces of the front and back surfaces of the AT-cut quartz substrate,
The outer shape of the AT-cut quartz substrate is a strip whose main surface is rectangular,
Provided with a plurality of grooves formed by etching between the short side of the strip and the excitation electrode,
A pair of side walls constituting the groove is inclined with respect to the Y ′ axis due to anisotropy in the crystal axis direction of the crystal,
The depth of the groove in the direction parallel to the Y ′ axis is the depth to the point where the pair of side walls intersect ,
An opening of the groove is curved toward the excitation electrode with a predetermined curvature . Wherein the plurality of grooves claim each said varied the parallel width to the long side of the strip of the opening, characterized in that with different parallel direction depth to the Y 'axis 1 The piezoelectric vibrator described in 1. The length of the groove in the direction parallel to the short side of the strip is in claim 1 or 2, wherein the at least the length of the direction parallel to the short sides of the strip edges of the excitation electrodes The piezoelectric vibrator as described. The depth in the direction parallel to the Y ′ axis of the groove closest to the excitation electrode is:
The piezoelectric vibrator according to any one of claims 1 to 3, wherein the piezoelectric vibrator is shallower than a depth of another groove. The depth of the plurality of grooves in the direction parallel to the Y ′ axis is shallower as the groove is closer to the excitation electrode.
The piezoelectric vibrator according to claim 4 , wherein a groove closer to a short side of the strip is deepened. Centering on the X axis of an orthogonal coordinate system consisting of an X axis as an electric axis, a Y axis as a mechanical axis, and a Z axis as an optical axis, which are crystal axes of quartz, the Z axis is the Y axis. The axis tilted in the -Y direction is the Z 'axis, the Y axis is tilted in the + Z direction of the Z axis as the Y' axis, and is composed of planes parallel to the X axis and the Z 'axis. An AT-cut quartz substrate having a thickness parallel to the Y′-axis and a thickness-shear vibration as a main vibration;
An excitation electrode provided on each of the main surfaces of the front and back surfaces of the AT-cut quartz substrate,
The outer shape of the AT-cut quartz substrate is a strip whose main surface is rectangular,
A plurality of grooves are provided between the short side of the strip and the excitation electrode,
The plurality of grooves extend from the opposing long sides of the strip, and are arranged so as to be inserted between each other.
A piezoelectric vibrator characterized in that a depth in a direction parallel to the Y′-axis of a groove at a desired position between the excitation electrode and the short side of the strip is made deeper than the depth of other grooves. Centering on the X axis of an orthogonal coordinate system consisting of an X axis as an electric axis, a Y axis as a mechanical axis, and a Z axis as an optical axis, which are crystal axes of quartz, the Z axis is the Y axis. The axis tilted in the -Y direction is the Z 'axis, the Y axis is tilted in the + Z direction of the Z axis as the Y' axis, and is composed of planes parallel to the X axis and the Z 'axis. An AT-cut quartz substrate having a thickness parallel to the Y′-axis and a thickness-shear vibration as a main vibration;
An excitation electrode provided on each of the main surfaces of the front and back surfaces of the AT-cut quartz substrate,
The outer shape of the AT-cut quartz substrate is a strip whose main surface is rectangular,
A plurality of grooves are provided between the short side of the strip and the excitation electrode,
The plurality of grooves extend from the opposing long sides of the strip, and are arranged so as to be inserted between each other.
The piezoelectric vibrator according to claim 1, wherein a depth in a direction parallel to the Y ′ axis of a groove closest to the excitation electrode and a groove closest to the next is shallower than a depth of another groove. The plurality of grooves from the opposing long sides of the strip,
8. The piezoelectric vibrator according to claim 6 , wherein the piezoelectric vibrator extends to the vicinity of a center line parallel to the opposing long sides of the strip and passing through a substantially central portion of the excitation electrode. Provide a notch on the short side of the strip,
Extending the lead electrode to the short side from the excitation electrode,
A conductor film on the inner wall of the notch,
The lead electrodes, the piezoelectric vibrator according to any one of claims 1 to 8, characterized in that said being conductive film electrically connected. A through hole is provided between the short side of the strip and the groove closest to the short side of the plurality of grooves, and a lead electrode extends from the excitation electrode to the through hole,
A conductor film on the inner wall of the through hole;
The lead electrodes, the piezoelectric vibrator according to any one of claims 1 to 8, characterized in that said being conductive film electrically connected. A first pair of sides constituting the strip is parallel to the X axis, and a second pair of sides is parallel to the Z ′ axis,
The long side of the strip is a side parallel to the X axis,
The piezoelectric vibrator according to any one of claims 1 to 10, characterized in that the short sides of the strip are sides parallel to the Z 'axis. Centering on the X axis of an orthogonal coordinate system consisting of an X axis as an electric axis, a Y axis as a mechanical axis, and a Z axis as an optical axis, which are crystal axes of quartz, the Z axis is the Y axis. The axis tilted in the -Y direction is the Z 'axis, the Y axis is tilted in the + Z direction of the Z axis as the Y' axis, and is composed of planes parallel to the X axis and the Z 'axis. An AT-cut quartz substrate having a thickness parallel to the Y′-axis and a thickness-shear vibration as a main vibration;
An excitation electrode provided on each of the main surfaces of the front and back surfaces of the AT-cut quartz substrate,
The outer shape of the AT-cut quartz substrate is a strip whose main surface is rectangular,
Add an additive between the short side of the strip and the excitation electrode,
A piezoelectric vibrator, wherein a doping layer is provided between the excitation electrode and the short side of the strip, and a vibration region immediately below the excitation electrode is sandwiched in the X-axis direction by the doping layer. The piezoelectric vibrator according to claim 12 , wherein the additive is added using an ion implantation technique or a gas phase thermal diffusion technique. A first pair of sides constituting the strip is parallel to the X axis, and a second pair of sides is parallel to the Z ′ axis,
The long side of the strip is a side parallel to the X axis,
The piezoelectric vibrator according to claim 12 or 13, wherein the short side of the strip are sides parallel to the Z 'axis.

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