JP6344677B2 - Crystal resonator element and crystal unit - Google Patents

Description

  The present invention relates to a crystal resonator element and a crystal resonator.

  As a quartz crystal vibrating piece formed by wet etching, for example, a mesa type or inverted mesa type quartz crystal vibrating piece as disclosed in Patent Document 1 is known.

JP 2011-66905 A

  In such a mesa type or inverted mesa type crystal vibrating piece, the step is formed by wet etching, and the side wall becomes a natural crystal plane. Since the natural crystal plane has an arrangement location and angle determined by the etching anisotropy peculiar to quartz, the inclination angle of the side wall varies depending on the location where it is formed, and the isotropicity of the crystal vibrating piece may be lost. . As a result, there is a problem that the isotropy of vibration starting from the excitation electrode is lost and the vibration characteristics are deteriorated.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a crystal resonator element and a crystal having excellent vibration characteristics by having substantially equal inclination angles of formed surfaces and having isotropic properties. It is to obtain a vibrator.

A quartz crystal resonator element according to one aspect of the present invention is a quartz crystal resonator element formed by AT cut, a main surface having an excitation electrode formed in the center thereof, connected to the main surface, and in a predetermined direction on the main surface. Provided at least one pair of slopes provided symmetrically with respect to the center, a central part comprising the main surface and the slopes, and a peripheral part formed with a thickness different from the thickness of the central part. , the set of slope, the difference in inclination angle of each of the inclined surface with respect to the main surface is within 10 °, the tilt angle is rather smaller than the angle between the main surface and the natural crystal surface, wherein The inclined surface connects the surface of the peripheral portion and the main surface .

  According to this configuration, at least one pair of inclined surfaces provided symmetrically with respect to the center of the main surface provided with the excitation electrode is inclined at substantially the same angle. Therefore, it is possible to obtain a vibration isotropy starting from the excitation electrode and to obtain a quartz crystal resonator element having excellent vibration characteristics.

  Further, by obtaining vibration isotropy, the frequency difference between the thickness-slip main vibration and the thickness sub-vibration can be increased, and the vibration strength of the thickness sub-vibration can also be reduced. Therefore, stable vibration can be obtained.

The inclination angle may be smaller than an angle formed between a natural crystal plane and the main surface.
According to this structure, it can suppress that a vibration oscillates in the boundary part of a main surface and a slope, and can attenuate the vibration transmitted to an edge part. Therefore, a quartz crystal resonator element having excellent vibration energy confinement accuracy can be obtained.

A central portion provided with the main surface and the slope, and a peripheral portion formed with a thickness different from the thickness of the central portion, the slope connecting the surface of the peripheral portion and the main surface. May be.
According to this configuration, a quartz crystal resonator element having excellent mesa-type or inverted mesa-type vibration characteristics can be obtained.

The inclination angle may be 20 ° or less.
According to this configuration, it is possible to obtain a quartz crystal resonator element with excellent vibration energy confinement accuracy.

The crystal resonator of the present invention includes the crystal resonator element of the present invention.
According to this configuration, since the above-described crystal vibrating piece is provided, a crystal resonator having excellent vibration characteristics can be obtained.

  According to the present invention, a crystal resonator element and a crystal resonator having excellent vibration characteristics can be obtained by having substantially equal inclination angles of formed surfaces and isotropic properties.

It is a disassembled perspective view which shows embodiment of a crystal oscillator. FIG. 3 is a perspective view of a rough Lumbard stone for explaining a cutting angle of a quartz plate and a coordinate axis of a quartz crystal. It is a figure which shows 1st Embodiment, Comprising: (a) is a front view, (b) is a top view, (c) is a side view. It is a flowchart which shows a part of manufacturing process of the crystal vibrating piece of 1st Embodiment. It is sectional drawing and a top view which show the procedure of the manufacturing process of the quartz crystal vibrating piece of 1st Embodiment. It is a figure which shows 2nd Embodiment, Comprising: (a) is a front view, (b) is a top view, (c) is a side view. It is a figure which shows 3rd Embodiment, Comprising: (a) is a front view, (b) is a top view, (c) is a side view. It is a figure which shows 4th Embodiment, (a) is a front view, (b) is a top view, (c) is a side view.

Hereinafter, a crystal resonator element, a method for manufacturing a crystal resonator element, and a crystal resonator according to an embodiment of the present invention will be described with reference to the drawings.
The scope of the present invention is not limited to the following embodiment, and can be arbitrarily changed within the scope of the technical idea of the present invention. Moreover, in the following drawings, in order to make each structure easy to understand, the actual structure may be different from the scale, number, or the like in each structure.

[First Embodiment]
FIG. 1 is an exploded perspective view showing the crystal resonator of the present embodiment.
As shown in FIG. 1, the crystal resonator 1 according to the present embodiment is formed in a box shape in which a base substrate 2 and a lid substrate 3 are laminated in two layers. Is mounted.
The crystal vibrating piece 4 includes a crystal vibrating plate 10 and a pair of electrode films 20 respectively formed on the crystal vibrating plate 10.

As shown in FIG. 2, the quartz diaphragm 10 is formed by AT-cutting the quartz lambard ore 6 in which the coordinate axes of the quartz crystal are defined by the X axis, the Y axis, and the Z axis (the front and back main surfaces are rotated from the Z axis around the X axis). The quartz plate 7 obtained by cutting the lens so as to have an angle of about 35 degrees 15 minutes in the counterclockwise direction is formed into a rectangular shape in plan view by wet etching after that.
FIG. 2 is a perspective view of the lumbar raw stone 6 for explaining the cutting angle of the quartz plate 7 and the coordinate axes of the quartz crystal. Further, in the present embodiment, the Z ′ axis is a crystal axis in a direction orthogonal to the X axis on the front and back main surfaces of the crystal diaphragm 10 as shown in FIG. 1, and the Y ′ axis is the X axis and the Z axis. 'A crystal axis perpendicular to the axis.

3A and 3B are diagrams showing the crystal vibrating piece 4, in which FIG. 3A is a front view, FIG. 3B is a plan view, and FIG. 3C is a side view.
As shown in FIG. 3, the crystal diaphragm 10 includes a central portion 30 and a peripheral portion 31. The peripheral part 31 is a rectangular parallelepiped, and is provided at both ends of the central part 30 in the long side direction (X-axis direction).

The central part 30 includes a base 30a and a convex part 30b.
The base 30a is a rectangular parallelepiped.
The convex portion 30b has a trapezoidal quadrangular prism shape. The convex portion 30b is provided on the base portion 30a so that the short side of the trapezoid is on the upper side (+ Y ′ direction side). The convex portions 30b are along the main surface 10a and both ends of the main surface 10a in the long side direction (X-axis direction) of the crystal plate 10 along the short side direction (Z′-axis direction) of the crystal plate 10. The slopes 11a and 11b are formed. The inclined surface 11a is inclined at an angle θ1 with respect to the front main surface 10a over the entire length of the short side on the + X direction side of the front main surface 10a. The inclined surface 11b is inclined at an angle θ2 with respect to the front main surface 10a over the entire length of the short side on the −X direction side of the front main surface 10a.

  The angles θ1 and θ2 of the inclined surfaces 11a and 11b of the crystal vibrating piece 4 are substantially equal angles, and are smaller than the value of the angle formed by the natural crystal surface and the main surface of the crystal vibrating piece. The angles θ1 and θ2 are, for example, 20 ° or less.

As shown in FIGS. 1 and 3, the pair of electrode films 20 each include an excitation electrode 21, an extraction electrode 22, and a mount electrode 23.
The excitation electrodes 21 are formed at substantially central portions of the front and back main surfaces 10a and 10b of the quartz crystal plate 10 so as to face each other with the crystal plate 10 interposed therebetween. Mount electrodes 23 are respectively provided at both end portions in the short side direction (Z′-axis direction) of the crystal plate 10 in the peripheral portion 31 on one side (−X direction side). The mount electrode 23 is formed from the surface 12a on the front main surface 10a side in the peripheral portion 31 to the surface on the back main surface 10b side through the side surface.

Of the mount electrodes 23, one mount electrode 23 is electrically connected to one excitation electrode 21 formed on the front main surface 10 a via the extraction electrode 22, and the other mount electrode 23 is the extraction electrode 22. Is electrically connected to the other excitation electrode 21 formed on the main surface 10b on the back side.
The electrode film 20 including the excitation electrode 21, the extraction electrode 22, and the mount electrode 23 described above is a single layer film such as gold, or a laminate in which a metal layer such as gold is stacked on a metal such as chromium as a base layer. It is formed of a film.

The quartz crystal vibrating piece 4 configured in this way is mounted on the upper surface 2a of the base substrate 2 as shown in FIG. 1 using mounting members such as bumps and conductive adhesive. More specifically, the pair of mount electrodes 23 formed on the back main surface 10b of the crystal diaphragm 10 are in contact with the inner electrode 300 formed on the upper surface 2a of the base substrate 2 via the mounting member. Mounted in state.
Thereby, the quartz crystal vibrating piece 4 is mechanically held on the upper surface 2a of the base substrate 2, and the inner electrode 300 and the mount electrode 23 are electrically connected to each other.

Next, with reference to FIG. 4 and FIG. 5, the manufacturing method of the inclined surface of the crystal vibrating piece 4 is demonstrated.
FIG. 4 is a flowchart showing a process of forming the slopes 11a and 11b in the manufacturing process of the crystal vibrating piece 4.
FIG. 5 is a cross-sectional view and a plan view showing a procedure for forming the inclined surfaces 11a and 11b in the manufacturing process of the quartz crystal vibrating piece 4.

As shown in FIG. 4, the formation process of the inclined surfaces 11 a and 11 b in the method for manufacturing the quartz crystal resonator element of the present embodiment includes a wafer preparation process S <b> 1 and a recess formation process S <b> 2.
First, as shown in FIG. 4, a rough Lambert stone crystal is AT-cut and lapped to a constant thickness, and then rough-processed. Then, the work-affected layer is removed by etching, and then mirror polishing such as polishing is performed. To prepare a wafer S (see FIG. 5A) having a predetermined thickness (S1).

 The recess forming step S2 is a step of forming a later-described recess 42 on the surface of the wafer S.

First, as shown in FIG. 5A, the surface of the wafer S is dry-etched (S2a).
The dry etching is not particularly limited as long as the slope 11a can be formed in the step S2f of performing the slope etching process on the wafer S, which will be described later, on the surface of the wafer S. For example, reactive ion etching (RIE) or reverse sputtering can be selected.
By this step, the surface of the wafer S is flattened.

Next, as shown in FIG. 5B, an etching protection film 40 and a photoresist film 41 are respectively formed on both surfaces of the wafer S (S2b).
The etching protective film 40 is a laminated film in which, for example, an etching protective film in which chromium (Cr) is formed to several tens of nm and an etching protective film in which gold (Au) is formed to several tens of nm are sequentially laminated.

In this step S2b, first, an etching protective film 40 is sequentially formed on the front and back main surfaces of the wafer S by a sputtering method, a vapor deposition method, or the like.
Next, a resist material is applied on the etching protection film 40 by a spin coating method or the like to form a photoresist film 41.
As a resist material used in the present embodiment, a rubber negative resist mainly composed of cyclized rubber (for example, cyclized isoprene) is preferably used. The rubber negative resist is refined by dissolving cyclized rubber in an organic solvent, adding a bisazide photosensitizer, filtering, and removing impurities.

Next, the surface on one side (+ Y ′ direction side) of the wafer S on which the etching protective film 40 and the photoresist film 41 are formed is exposed and developed in a lump using a photomask on which an external pattern is formed. .
As a result, as shown in FIG. 5C, an outer pattern 41a is formed on one side of the photoresist film 41 (S2c).
The outer shape pattern 41 a has a shape that follows the outer shape of the crystal diaphragm 10.

Next, etching is performed using the photoresist film 41 on which the outer pattern 41a is formed as a mask, and the unmasked etching protection film 40 is selectively removed (S2d).
Next, the photoresist film 41 is removed after the etching process (S2e).
As a result, as shown in FIG. 5D, an outer pattern 40 a is formed on one side of the etching protection film 40.

For the etching process, a wet etching method in which the wafer S on which the etching protective film 40 and the photoresist film 41 are formed is immersed in a chemical solution can be used.
Specifically, for example, when the etching protection film 40 is made of gold (Au), it can be etched using iodine as a chemical solution.
This patterning is performed collectively for the number of the plurality of quartz crystal plates 10.

Next, the unmasked wafer S is selectively etched by a slope using the outer pattern 40a of the etching protective film 40 as a mask (S2f).
As a result, as shown in FIG. 5E, the lower portion of the mask is also etched from the exposed surface of the unmasked wafer S, and the inclined surface 11a intersects the main surface of the wafer S at a gentle angle. , 11b as side surfaces.

Here, normally, in the etching of quartz, a natural crystal plane having a specific angle appears due to etching anisotropy peculiar to quartz. Moreover, it is hardly seen that etching progresses from the exposed surface not masked to the lower side (inside) of the mask.
On the other hand, in this embodiment, since the surface of the wafer S is dry-etched (S1) before the slope etching is performed, the etching proceeds to the lower side of the mask, and the angle of the natural crystal plane is reached. A slope having a gentle angle that does not depend can be formed.

Next, as shown in FIG. 5F, etching is performed to remove the etching protective film 40 (S2g).
Through the above steps, the recess forming step S2 is completed, and the wafer S in which the recesses 42 are formed is obtained.

  The slopes 11a and 11b are formed by the above steps S1 and S2. Thereafter, the crystal plate 10 is obtained by dividing the wafer S on which the inclined surfaces 11a and 11b are formed into individual pieces.

  According to the quartz crystal resonator element of the present embodiment, the inclination angle θ1 of the inclined surface 11a with respect to the front main surface 10a is substantially equal to the inclination angle θ2 of the inclined surface 11b with respect to the front main surface 10a, and the crystal vibrating plate 10 is excited. The electrodes 21 are symmetrical with respect to the X, Y ′, and Z ′ axes that pass through the centers of the front and back main surfaces 10a and 10b on which the electrodes 21 are formed. Therefore, vibration isotropy starting from the excitation electrode 21 is obtained, and a quartz crystal resonator element having excellent vibration characteristics is obtained.

  Further, by obtaining vibration isotropy, the frequency difference between the thickness-slip main vibration and the thickness sub-vibration can be increased, and the vibration strength of the thickness sub-vibration can also be reduced. Therefore, stable vibration can be obtained.

  Further, it is known that the quartz crystal vibrating piece has vibration modes such as bending vibration and contour sliding vibration in addition to thickness-shear vibration. When the influence of vibrations other than these thickness-shear vibrations (hereinafter referred to as unnecessary vibrations) is large, an activity dip occurs and the vibration characteristics of the quartz crystal vibrating piece become unstable.

  Thickness-sliding vibration depends on the thickness of the crystal vibrating piece, whereas many unnecessary vibrations depend on the length of the crystal vibrating piece. Therefore, unnecessary vibration is likely to occur at the end of the crystal vibrating piece. Therefore, unnecessary vibration can be suppressed by reducing the thickness of the crystal vibrating piece from the center to the end of the crystal vibrating piece to attenuate the vibration at the end. As a method of reducing the thickness of the quartz crystal vibrating piece from the center to the end of the quartz crystal vibrating piece, there is a method of providing an inclined surface at the end of the quartz crystal vibrating piece. Because the slope provided is the natural crystal plane of the crystal piece, the angle with respect to the main surface is large, and there is a problem that unnecessary vibration occurs at the position where the slope and the main surface intersect, not at the end of the crystal vibration piece. there were.

  On the other hand, according to the quartz crystal resonator element 4 of the present embodiment, the angles θ1 and θ2 of the inclined surfaces 11a and 11b are formed sufficiently gently (for example, 20 ° or less). Vibration transmission is not hindered at the position where the main surface 10a intersects, and generation of unnecessary vibration at the position where the slope and the main surface intersect can be suppressed. Further, since the vibration is sufficiently damped at the end portion, the influence of unnecessary vibration can be suppressed. As a result, the vibration characteristics of the quartz crystal resonator element can be stabilized.

  Further, in the mesa type crystal vibrating piece as in this embodiment, the excitation electrode is formed on the main surface on the convex portion, and the mount electrode is formed on the surface of the peripheral portion. Therefore, the extraction electrode that connects the excitation electrode and the mount electrode is formed on a slope connecting the main surface and the surface of the peripheral portion. These electrodes are formed by sputtering or the like, but when the inclination angle of the inclined surface with respect to the main surface is large (for example, 90 °), the sputtered particles are adhered from the side facing the main surface and the peripheral surface. In this case, there are few sputtered particles adhering to the slope, and it becomes difficult to form an electrode film having a sufficient thickness. As a result, the resistance value of the extraction electrode is increased, and the resistance value of the crystal vibrating piece may be increased.

  On the other hand, according to the quartz crystal vibrating piece 4 of the present embodiment, the inclined surface 11b has a gentler inclination angle with respect to the front principal surface 10a than the natural crystal surface. Therefore, even when the sputtered particles are attached so as to face the front main surface 10a and the surface of the peripheral portion 31 on the front main surface 10a side, the extraction electrode 22 is formed on the inclined surface 11b with a sufficient thickness. Is easy. Therefore, it is possible to employ a method for forming an electrode film by sputtering. As a result, a crystal resonator element having a low resistance value can be obtained.

  In addition, the inclined surface of the quartz crystal vibrating piece 4 manufactured by the above-described manufacturing method is not formed into a curved surface as manufactured by conventional machining, but is formed as a flat surface with high flatness. Further, in the conventional machining, the connecting portion between the inclined surface and the main surface is continuously formed in a curved shape. However, in the crystal vibrating piece 4 manufactured by the above-described manufacturing method, the connection between the inclined surface and the main surface is performed. The parts are clearly separated. This is because such a connecting portion is formed in a shape having an angle when viewed from the cross section by connecting the main surface having the same flatness as the slope having the higher flatness. Therefore, the flatness of the entire main surface is ensured, and the parallelism of the front and back surfaces of the main surface is increased, so that a desired Q value as a crystal resonator can be ensured.

[Second Embodiment]
Next, a description will be given of a second embodiment, which is a crystal vibrating piece in which convex portions 30b are provided on both sides in the thickness direction (Y-axis direction) of the base portion 30a.
6A and 6B are diagrams illustrating the quartz crystal resonator element 5 of the present embodiment, in which FIG. 6A is a front view, FIG. 6B is a plan view, and FIG. 6C is a side view.
As shown in FIG. 6, the crystal vibrating piece 5 includes a crystal vibrating plate 10 </ b> A and a pair of electrode films 20 formed on the crystal vibrating plate 10 </ b> A.

The crystal diaphragm 10A includes a central portion 30A and a peripheral portion 31.
The central portion 30A includes a base portion 30a and two convex portions 30b. The surface of the convex portion 30b provided on the + Y direction side is the main surface 10a, and the surface of the convex portion 30b provided on the −Y axis direction side is the back main surface 10b. On the + X direction side of the quartz diaphragm 10A of the front and back main surfaces 10a and 10b, slopes 11a that are inclined at an angle θ1 with respect to the front and back main surfaces 10a and 10b are respectively provided, and on the −X direction side, the front and back surfaces are respectively provided. A slope 11b that is inclined at an angle θ2 with respect to the main surfaces 10a and 10b is provided. The angle θ1 and the angle θ2 are substantially equal, and are gentler than the angle formed between the natural crystal plane and the front and back main surfaces 10a and 10b.

  As in this embodiment, in the mesa-type crystal vibrating piece in which convex portions are provided on both sides, the inclination angles of the inclined surfaces provided on both surfaces are different, and the inclination angle is large (for example, 90 °) When a slope is included, the formation position of the mount electrode may be limited because it is difficult to form the extraction electrode on the slope as described above.

  On the other hand, according to the present embodiment, the angles θ1 and θ2 of the slopes 11a and 11b provided on both surfaces are all gentle slopes, so that it is possible to prevent the mount electrode formation position from being limited. .

[Third Embodiment]
Next, a third embodiment will be described in which convex portions are provided on both sides, and slopes are provided on the four sides around the convex portions.
FIGS. 7A and 7B are views showing the quartz crystal vibrating piece 120 of the third embodiment, in which FIG. 7A is a front view, FIG. 7B is a plan view, and FIG. 7C is a side view.
As shown in FIG. 7, the quartz crystal vibrating piece 120 includes a quartz crystal plate 121 and a pair of electrode films 20 formed on the front and back main surfaces of the quartz plate 121.

The quartz crystal diaphragm 121 includes a rectangular parallelepiped 200a and quadrangular pyramid-shaped convex portions 200b provided at the centers of base surfaces 124a and 124b of the rectangular parallelepiped 200a.
The side surfaces 122b and 123b of the rectangular parallelepiped 200a are provided substantially perpendicular to the base surfaces 124a and 124b.
The convex part 200b is provided so that the surface with the larger area is in contact with the base surfaces 124a and 124b of the rectangular parallelepiped 200a, and the opposite surface is the front and back main surfaces 121a and 121a of the crystal vibrating piece 120, respectively. 121b. Excitation electrodes 21 are provided on the front and back main surfaces 121a and 121b, and the front and back main surfaces 121a and 121b are parallel to the base surfaces 124a and 124b of the rectangular parallelepiped 200a.

  In the convex portion 200b, the slope 122a along the short side direction (Z′-axis direction) and the slope 123a along the long side direction (X-axis direction) have angles with respect to the front and back main surfaces 121a and 121b, respectively, from the natural crystal plane. Is also formed at a gentle and substantially equal angle.

  In the present embodiment, the central portion 32 is composed of the convex portion 200b and a portion sandwiched between the convex portions 200b in the rectangular parallelepiped 200a, and the peripheral portion 33 excludes the portion of the rectangular parallelepiped 200a in the central portion. The remaining part of the rectangular parallelepiped 200a is configured.

[Fourth Embodiment]
Next, a fourth embodiment which is an inverted mesa type crystal vibrating piece will be described.
FIGS. 8A and 8B are views showing a crystal vibrating piece 130 according to the fourth embodiment, in which FIG. 8A is a front view, FIG. 8B is a plan view, and FIG. 8C is a side view.
As shown in FIG. 8, the quartz crystal vibrating piece 130 includes a quartz crystal vibrating plate 131 and a pair of electrode films 20 formed on the front and back main surfaces of the quartz crystal vibrating plate 131.

The quartz diaphragm 131 is a rectangular parallelepiped, and a recess 210 is formed at the center of each of the base surfaces 134a and 134b. The side surfaces 132b and 133b of the crystal diaphragm 131 are provided substantially perpendicular to the base surfaces 134a and 134b.
The recess 210 is formed so that the side surface is a slope. The bottom surfaces of the recesses 210 are front and back main surfaces 131a and 131b on which the excitation electrode 21 is formed, and are formed in parallel with the base surfaces 134a and 134b of the quartz crystal vibrating plate 131. The slope 133a which is a side surface along the long side direction (X-axis direction) of the recess 210 and the slope 132a which is a side surface along the short side direction (Z′-axis direction) have angles with respect to the front and back main surfaces 131a and 131b, respectively. It is gentler than the natural crystal plane and formed at substantially the same angle.

  In the present embodiment, the central portion 34 is formed by a portion of the rectangular parallelepiped 200a formed with the concave portion 210 and sandwiched by the concave portion 210, and the peripheral portion 35 excludes the portion of the rectangular parallelepiped 200a in the central portion. It consists of the remaining part of the rectangular parallelepiped 200a.

  In the embodiment described above, the inclination angle of the inclined surface is substantially equal includes the case where the difference in inclination angle between the inclined surfaces is within 10 °.

  In addition, although embodiment shown above is a mesa type | mold and reverse mesa type | mold crystal vibrating piece, it is not restricted to this, The simple rectangular quartz crystal vibrating piece in which the level | step difference is not provided may be sufficient.

  In the embodiment described above, the long side direction is the X-axis direction and the short side direction is the Z′-axis direction, but the long side direction is the Z′-axis direction and the short side direction is the X-axis direction. You can also. Moreover, it can also be made into the square which makes the X-axis direction and Z'-axis direction the edge | side of the same length. Further, it can be rotated in the XZ ′ plane so that the direction of each side is shifted by a predetermined angle from the X-axis direction or the Z′-axis direction.

  DESCRIPTION OF SYMBOLS 1 ... Quartz crystal oscillator, 4, 5, 120, 130 ... Quartz vibrating piece, 10a, 121a, 131a ... Front main surface, 10b, 121b, 131b ... Back main surface, 21 ... Excitation electrode, 11a, 11b, 122a, 123a , 132a, 133a ... slope, 30, 32, 34 ... central part, 31, 33, 35 ... peripheral part

Claims (3)

In the crystal vibrating piece formed by AT cut,
A main surface on which an excitation electrode is formed in the center;
At least one set of slopes connected to the main surface and provided symmetrically with respect to a center in a predetermined direction on the main surface;
A central portion comprising the main surface and the slope;
A peripheral part formed with a thickness different from the thickness of the central part;
With
The set of slope, the difference in inclination angle of each of the inclined surface with respect to the main surface is within 10 °, the tilt angle is rather smaller than the angle between the main surface and the natural crystal surface,
The inclined surface connects the surface of the peripheral portion and the main surface . The inclination angle is 20 ° or less, in the quartz crystal resonator element according to claim 1.   A crystal resonator comprising the crystal resonator element according to claim 1.

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