JP5908630B2 - Piezoelectric vibrating piece, piezoelectric vibrator, and method of manufacturing piezoelectric vibrating piece - Google Patents

Description

  The present invention relates to a piezoelectric vibrating piece, a piezoelectric vibrator, and a method for manufacturing a piezoelectric vibrating piece.

In a piezoelectric vibrating piece formed by AT-cut, a structure is known in which the thickness of the end is reduced and the vibration transmitted to the end is attenuated in order to confine the vibration energy due to the thickness-shear vibration in the center of the piezoelectric vibrating piece. ing. For example, in a so-called convex type piezoelectric vibrating piece, the thickness of the end portion is reduced by forming the main surface into a convex curved surface.
Further, in the piezoelectric vibrating piece described in Patent Document 1, a slope is formed at the end by wet etching in order to reduce the thickness of the end. At this time, since the piezoelectric vibrating piece formed by the AT cut has crystal anisotropy, the inclined surface formed by wet etching has natural surfaces other than the m-plane and the m-plane of the quartz crystal having a specific inclination angle. It becomes a crystal plane.

Japanese Patent No. 4305542

However, since the thickness of the convex-type piezoelectric vibrating piece among the piezoelectric vibrating pieces described above varies depending on the position of the main surface, in order to make the inside of the excitation unit have substantially the same natural frequency, It must be formed in a narrow area in the center of the main surface with little change. As a result, the crystal impedance (CI value) of the piezoelectric vibrating piece increases, and good vibration characteristics cannot be obtained.
In addition, the piezoelectric vibrating piece described in Patent Document 1 has a principal surface because a slope formed by a crystal plane other than the m-plane among slopes that are natural crystal planes is connected at an angle close to a right angle with respect to the principal surface. A sharp ridge line is formed at the connection between the ridge and the slope. As a result, the vibration transmitted without being sufficiently attenuated is reflected at the ridgeline portion, spurious oscillation occurs, and the vibration characteristics deteriorate.

  Accordingly, the present invention provides a piezoelectric vibrating piece having excellent vibration characteristics, a piezoelectric vibrator, and a method for manufacturing the piezoelectric vibrating piece.

In order to solve the above problems, the piezoelectric vibrating piece of the present invention is a piezoelectric vibrating piece formed by AT cut and having a pair of main surfaces and side surfaces, wherein the pair of main surfaces are flat surfaces, At least a part of the side surface is formed by a curved surface continuous with at least one of the pair of main surfaces.
According to the present invention, since the piezoelectric vibrating piece has a pair of main surfaces formed as flat surfaces, the excitation electrode can be formed in a wide region within the main surface, and an increase in CI value can be suppressed. . In addition, since at least a part of the side surface is formed by a curved surface continuous with one main surface, compared with the case where the side surface is formed by a slope, the one main surface and the side surface are connected smoothly, The ridgeline at the connecting portion becomes dull. As a result, the reflection of vibration transmitted to the connecting portion without being sufficiently attenuated is reduced, and spurious oscillation is suppressed. Therefore, a piezoelectric vibrating piece having excellent vibration characteristics can be obtained.

In the piezoelectric vibrating piece, the side surface is formed from a plurality of partial side surfaces including the curved surface, and the partial side surface connected to the other of the pair of main surfaces has an obtuse angle with the other main surface. It is desirable that it be formed with a slope.
According to this configuration, since the partial side surface connected to the other main surface is formed as an inclined surface whose inner angle with the other main surface is an obtuse angle, the end portion of the piezoelectric vibrating piece is centered in the thickness direction. It can form in the shape which tapers toward. As a result, the end portion of the piezoelectric vibrating piece is thinner than when the side surface is formed of only one curved surface, so that the vibration transmitted to the end portion can be sufficiently attenuated, and the vibration energy is confined in the central portion. Accuracy can be improved. Further, the cross-sectional shape of the end portion of the piezoelectric vibrating piece is improved in symmetry in the thickness direction, so that an increase in the intensity of the secondary vibration can be suppressed. Therefore, a piezoelectric vibrating piece with more excellent vibration characteristics can be obtained.

In the above piezoelectric vibrating piece, it is preferable that the inclined surface is formed by an m-plane of a crystal crystal.
According to this configuration, the slope formed by the m-plane of the crystal crystal is formed with an inner angle of about 150 degrees with the main surface of the AT vibrating piece, so that the taper shape of the end portion of the piezoelectric vibrating piece is tapered more gently. It can be realized with an inclination. Thereby, the attenuation rate of the vibration transmitted to the end of the piezoelectric vibrating piece is increased, and the confinement accuracy of the vibration energy in the center is further increased. Therefore, a piezoelectric vibrating piece with more excellent vibration characteristics can be obtained.

In the above piezoelectric vibrating piece, it is preferable that all the side surfaces have at least the curved surface.
According to this configuration, the vibration transmitted to any end portion of the piezoelectric vibrating piece can be sufficiently damped, and the confinement accuracy of the vibration energy in the central portion is further increased. Therefore, a piezoelectric vibrating piece with more excellent vibration characteristics can be obtained.

In the piezoelectric vibrating piece described above, it is desirable that the maximum value of the projected width of the side surface viewed from the thickness direction of the piezoelectric vibrating piece is smaller than twice the minimum value of the distance between the pair of main surfaces.
According to this configuration, since the area of the main surface of the piezoelectric vibrating piece can be formed wide, the excitation electrode can be formed in a wider region, and the CI value can be reduced. Therefore, a piezoelectric vibrating piece with more excellent vibration characteristics can be obtained.

In the above-described piezoelectric vibrating piece, it is preferable that the main surface has a convex portion.
According to this configuration, vibration energy can be confined in the convex portion, so that a piezoelectric vibrating piece with more excellent vibration characteristics can be obtained.

The piezoelectric vibrator of the present invention includes the above-described piezoelectric vibrating piece.
According to this configuration, since the piezoelectric vibrator includes the above-described piezoelectric vibrating piece having excellent vibration characteristics, a piezoelectric vibrator having excellent vibration characteristics can be obtained.

A method of manufacturing a piezoelectric vibrating piece according to the present invention is a method of manufacturing a piezoelectric vibrating piece formed by AT cut and having a pair of main surfaces and side surfaces, wherein a first outer pattern of the piezoelectric vibrating piece is formed on the surface of a wafer. Forming a mask; etching the wafer through the first mask to form an outer shape pattern of the piezoelectric vibrating piece; and wet-etching the wafer, whereby at least one of the pair of main surfaces Forming a curved surface connected to one side on the side surface.
According to the present invention, by performing wet etching on the piezoelectric vibrating piece on which the outer shape pattern is formed, the ridge line between one main surface and the side surface is rounded, and the side surface changes to a curved surface. Therefore, a piezoelectric vibrating piece having a curved surface continuous with one main surface can be easily manufactured.

In the method for manufacturing the piezoelectric vibrating piece, the piezoelectric vibrating piece has a convex portion on the main surface, and the outer shape of the convex portion is formed on the surface of the wafer after the step of forming the outer shape pattern of the piezoelectric vibrating piece. A step of forming a second mask of the pattern, and a step of wet-etching the wafer through the second mask to form an outer shape pattern of the convex portion. In the step of forming the outer shape pattern of the part, it is preferable to perform the wafer by wet etching.
According to this method, the curved surface of the side surface can be formed simultaneously with the formation of the convex portion on the main surface of the piezoelectric vibrating piece. Therefore, a curved surface connected to one main surface can be easily formed without adding a special process to the piezoelectric vibrating piece having a convex portion on the main surface.

  According to the piezoelectric vibrating piece of the present invention, since the piezoelectric vibrating piece has a pair of main surfaces formed by flat surfaces, the excitation electrode can be formed in a wide region within the main surface, and an increase in CI value is suppressed. can do. In addition, since at least a part of the side surface is formed by a curved surface continuous with one main surface, compared with the case where the side surface is formed by a slope, the one main surface and the side surface are connected smoothly, The ridgeline at the connecting portion becomes dull. As a result, the reflection of vibration transmitted to the connecting portion without being sufficiently attenuated is reduced, and spurious oscillation is suppressed. Therefore, a piezoelectric vibrating piece having excellent vibration characteristics can be obtained.

  According to the method for manufacturing a piezoelectric vibrating piece of the present invention, by performing wet etching on the piezoelectric vibrating piece having an outer shape pattern, the ridge line between one main surface and the side surface is rounded, and the side surface is curved. Change. Therefore, a piezoelectric vibrating piece having a curved surface continuous with one main surface can be easily manufactured.

FIG. 3 is a plan view of the piezoelectric vibrating piece according to the first embodiment. It is explanatory drawing of the piezoelectric vibrating piece which concerns on 1st Embodiment, and is sectional drawing in the II-II line of FIG. It is explanatory drawing of the piezoelectric vibrating piece which concerns on 1st Embodiment, and is sectional drawing in the III-III line of FIG. FIG. 3 is an exploded perspective view showing the piezoelectric vibrator according to the first embodiment. It is process drawing explaining the manufacturing method of the piezoelectric vibrating piece which concerns on 1st Embodiment. It is process drawing explaining the manufacturing method of the piezoelectric vibrating piece which concerns on 1st Embodiment. It is process drawing explaining the manufacturing method of the piezoelectric vibrating piece which concerns on 1st Embodiment. It is process drawing explaining the manufacturing method of the piezoelectric vibrating piece which concerns on 1st Embodiment. It is process drawing explaining the manufacturing method of the piezoelectric vibrating piece which concerns on 1st Embodiment. It is process drawing explaining the manufacturing method of the piezoelectric vibrating piece which concerns on 1st Embodiment. 6 is a plan view of a piezoelectric vibrating piece according to a first modification of the first embodiment. FIG. FIG. 12 is an explanatory diagram of a piezoelectric vibrating piece according to a first modification of the first embodiment, and is a cross-sectional view taken along line XII-XII in FIG. 11. It is process drawing explaining the manufacturing method of the piezoelectric vibrating piece which concerns on the 1st modification of 1st Embodiment. It is process drawing explaining the manufacturing method of the piezoelectric vibrating piece which concerns on the 1st modification of 1st Embodiment. It is process drawing explaining the manufacturing method of the piezoelectric vibrating piece which concerns on the 1st modification of 1st Embodiment. It is process drawing explaining the manufacturing method of the piezoelectric vibrating piece which concerns on the 1st modification of 1st Embodiment. It is process drawing explaining the manufacturing method of the piezoelectric vibrating piece which concerns on the 1st modification of 1st Embodiment. It is explanatory drawing of the piezoelectric vibrating piece which concerns on 2nd Embodiment, and is sectional drawing in the part corresponded to the II-II line of FIG. It is process drawing explaining the manufacturing method of the piezoelectric vibrating piece which concerns on 2nd Embodiment. It is process drawing explaining the manufacturing method of the piezoelectric vibrating piece which concerns on 2nd Embodiment. It is process drawing explaining the manufacturing method of the piezoelectric vibrating piece which concerns on 2nd Embodiment. It is process drawing explaining the manufacturing method of the piezoelectric vibrating piece which concerns on 2nd Embodiment. It is process drawing explaining the manufacturing method of the piezoelectric vibrating piece which concerns on 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In describing the configuration of each figure, an XY′Z ′ coordinate system is used. Each axis in the XY′Z ′ coordinate system has the following relationship with the crystal axis of crystal described later. That is, the X axis is an electrical axis, the Z ′ axis is an axis inclined by 35 degrees and 15 minutes around the X axis with respect to the Z axis which is an optical axis, and the Y ′ axis is orthogonal to the X axis and the Z ′ axis. It is an axis to do. In the X direction, the Y ′ direction, and the Z ′ direction, the arrow direction in the figure is defined as the + direction, and the direction opposite to the arrow is defined as the − direction.

(First Embodiment, Piezoelectric Vibrating Piece and Piezoelectric Vibrator)
First, the piezoelectric vibrating piece and the piezoelectric vibrator of the first embodiment will be described.
FIG. 4 is an exploded perspective view showing the piezoelectric vibrator of the present embodiment.

  As shown in FIG. 4, the piezoelectric vibrator 1 of the present embodiment is formed in a box shape in which a base substrate 3 and a lid substrate 5 are laminated in two layers, and the piezoelectric vibrating piece 10 is placed in an internal cavity 7. Is mounted.

The piezoelectric vibrating piece 10 includes a piezoelectric plate 20 and an electrode film 50 formed on the piezoelectric plate 20. The electrode film 50 has a pair of mount electrodes 55 formed on the second main surface 33.
The piezoelectric vibrating piece 10 is mounted on the upper surface 3a on the base substrate 3 using a mounting member such as a conductive adhesive. More specifically, a pair of mount electrodes 55 formed on the piezoelectric vibrating piece 10 is mounted on the pair of inner electrodes 9 formed on the upper surface 3a of the base substrate 3 via a mounting member.
Thereby, the piezoelectric vibrating reed 10 is mechanically held on the upper surface 3a of the base substrate 3 and the inner electrode 9 and the mount electrode 55 are electrically connected to each other.

FIG. 1 is a plan view of the piezoelectric vibrating piece according to the first embodiment. FIG. 2 is an explanatory diagram of the piezoelectric vibrating piece according to the first embodiment, and is a cross-sectional view taken along the line II-II in FIG. 1.
As shown in FIG. 1 and FIG. 2, the piezoelectric vibrating piece 10 of the present embodiment is a piezoelectric vibrating piece 10 that is formed by AT-cut and has a pair of main surfaces 30 and side surfaces 40, and the pair of main surfaces 30 includes It is a flat surface, and at least a part of the side surface 40 is formed by a curved surface continuous with at least one of the pair of main surfaces 30. In this application, when expressing the connection state between a flat surface and a curved surface, when the contact point between the curved surface and its tangent is brought close to the connection portion between the curved surface and the flat surface, the state in which the inclination of the tangent coincides with the inclination of the plane is expressed as `` It is expressed as “continuous”, and a state where the inclination of the tangent approximates the inclination of the plane is expressed as “continuous”. That is, “continuous” includes “continuous”.

The piezoelectric vibrating piece 10 is formed into a rectangular plate shape having a predetermined thickness by AT cut from artificial quartz crystal that has been subjected to lumbar processing, and has a pair of main surfaces 30 and side surfaces 40.
The AT cut is 35 degrees around the X axis with respect to the Z axis among the three crystal axes of the electric axis (X axis), the mechanical axis (Y axis), and the optical axis (Z axis), which are crystal axes of artificial quartz. This is a processing method of cutting in a direction inclined by 15 minutes (Z′-axis direction). The piezoelectric vibrating piece 10 cut out by the AT cut has the advantage that the frequency temperature characteristic is stable, the structure and shape are simple, the processing is easy, and the CI value is low. The piezoelectric vibrating piece 10 of the present embodiment is formed such that the length in the Z ′ direction is longer than the length in the X direction.

The pair of main surfaces 30 includes a first main surface 31 formed parallel to the XZ ′ plane and on the −Y ′ direction side, and a second main surface 33 formed on the + Y ′ direction side.
The side surface 40 includes a first side surface 41 formed on the side on the + Z ′ direction side, a second side surface 43 formed on the side on the −Z ′ direction side, and the + X direction among the four outer peripheral sides of the piezoelectric vibrating piece 10. A third side surface 45 formed on the side edge, and a fourth side surface 47 formed on the side surface on the −X direction side.

The piezoelectric vibrating piece 10 includes a first excitation electrode 51 formed on the first main surface 31 and a second excitation electrode 53 formed on the second main surface 33.
The first excitation electrode 51 is rectangular when viewed in the Y ′ direction, and is formed at the center position of the first main surface 31. The second excitation electrode 53 is rectangular when viewed in the Y ′ direction, and is formed at the center position of the second main surface 33. The second excitation electrode 53 is formed so as to overlap the first excitation electrode 51 when viewed in the Y ′ direction.

Further, the piezoelectric vibrating piece 10 includes a mount electrode 55 formed on the second main surface 33 and connected to the first excitation electrode 51 and the second excitation electrode 53.
The mount electrode 55 includes a first mount electrode 55a and a second mount electrode 55b. The first mount electrode 55 a is formed in a rectangular shape as viewed in the Y ′ direction, and is provided at a corner of the second main surface 33 on the −X side and the −Z ′ side so as not to overlap the second excitation electrode 53. It has been. The first mount electrode 55a is formed on the first main surface 31 via the first connection portion 61 formed on at least one of the −X side end and the −Z ′ side end of the piezoelectric vibrating piece 10. The first mount back electrode 65 is connected. The first mount back electrode 65 is formed so as to overlap the first mount electrode 55 a when viewed in the Y ′ direction, and is connected to the first excitation electrode 51 via the first routing wiring 57.
The second mount electrode 55 b is formed in a rectangular shape as viewed in the Y ′ direction, and is provided at a corner of the second main surface 33 on the + X side and the −Z ′ side so as not to overlap the second excitation electrode 53. ing. The second mount electrode 55 b is connected to the second excitation electrode 53 via the second routing wiring 59. Further, the second mount electrode 55b is formed on the first main surface 31 via the second connection portion 63 formed on at least one of the + X side end portion and the −Z ′ side end portion of the piezoelectric vibrating piece 10. The second mount back electrode 67 is connected to the formed second mount back electrode 67. The second mount back electrode 67 is formed so as to overlap the second mount electrode 55b when viewed in the Y ′ direction.

  The excitation electrode, mount electrode, routing wiring, mount back electrode, and connecting portion described above are laminated with a single layer film of metal such as gold, or a metal such as chromium as an underlayer and a metal such as gold as an upper layer. It is formed of a film or the like.

The first main surface 31 and the second main surface 33 of the piezoelectric vibrating piece 10 are formed as flat surfaces.
The first main surface 31 and the second main surface 33 are formed in parallel to each other. For example, the gap T is formed with an accuracy of less than 0.3%. By forming the first main surface 31 and the second main surface 33 in this way, even if the first excitation electrode 51 and the second excitation electrode 53 are formed in a wide area, the first excitation electrode 51 and the second excitation electrode 51 are formed. The thickness of the excitation part sandwiched between the electrodes 53 is uniform. Therefore, the natural frequencies in the excitation unit are substantially the same, and an increase in the CI value of the piezoelectric vibrating piece 10 can be suppressed.

(Side of piezoelectric vibrating piece)
FIG. 3 is an explanatory diagram of the piezoelectric vibrating piece according to the first embodiment, and is a cross-sectional view taken along line III-III in FIG. 1.
As shown in FIGS. 1 to 3, at least a part of the side surface 40 of the piezoelectric vibrating piece 10 is formed as a curved surface continuous with at least one of the pair of main surfaces 30. In the present embodiment, all the side surfaces 40 have curved surfaces that are continuous with at least one of the pair of main surfaces 30.
As shown in FIG. 2, the first side surface 41 is formed by a curved surface that continues to the second main surface 33. That is, the first side surface 41 is inclined in the (−Y ′, + Z ′) direction from the end portion on the + Z ′ direction side of the second main surface 33 and is connected to the end portion on the + Z ′ direction side of the first main surface 31. ing. The first side surface 41 is formed of a curved surface that is convex in the (+ Y ′, + Z ′) direction. The first side surface 41 is formed uniformly in the X direction. Since the first side surface 41 is formed by a curved surface that continues to the second main surface 33, the ridge line at the connection portion 33 a between the first side surface 41 and the second main surface 33 is blunt. In the present embodiment, since the first side surface 41 and the second main surface 33 are continuous, there is no ridgeline.

By the way, the conventional piezoelectric vibrating piece is formed in the cross-sectional shape shown in FIG. As shown in FIG. 9, in the conventional piezoelectric vibrating piece, the first side surface 41 and the second side surface 43 are formed of an R surface of a quartz crystal. The R plane appears so that the internal angle θ with the XZ ′ plane is about 93 degrees. Therefore, the first side surface 41 and the second side surface 43 are connected to the pair of main surfaces 30 at an angle close to a right angle, and a sharp ridge line is formed at the connection portion between the first side surface 41 and the second side surface 43 and the pair of main surfaces 30. It is formed. As described above, in the conventional piezoelectric vibrating piece, two connection portions each having a sharp ridge line are formed at the end portion on the + Z ′ direction side and the end portion on the −Z ′ direction side.
On the other hand, by forming the first side surface 41 with a curved surface as in the present embodiment shown in FIG. 2, the ridge line of the connecting portion between the first side surface 41 and the first main surface 31 or the second main surface 33 is formed. The sharp connection part is only one place of the connection part 31d. Thereby, the spurious oscillation generated at the end of the piezoelectric vibrating piece 10 on the + Z ′ direction side is suppressed.

  The second side surface 43 is formed by a curved surface that continues to the first main surface 31. That is, the second side surface 43 is inclined in the (+ Y ′, −Z ′) direction from the end portion on the −Z ′ direction side of the first main surface 31, and is on the end portion on the −Z ′ direction side of the second main surface 33. Connected. The second side surface 43 is formed of a curved surface that is convex in the (−Y ′, −Z ′) direction. The second side surface 43 is formed uniformly in the X direction. Since the second side surface 43 is formed by a curved surface continuous with the first main surface 31, the ridge line at the connection portion 31 a between the second side surface 43 and the first main surface 31 is dull. In the present embodiment, since the second side surface 43 and the first main surface 31 are continuous, there is no ridgeline. As a result, among the connecting portions between the second side surface 43 and the first main surface 31 or the second main surface 33, the sharp connecting portion of the ridge line is only one portion of the connecting portion 33d, and for the same reason as the first side surface 41. The spurious oscillation generated at the end of the piezoelectric vibrating piece 10 on the −Z ′ direction side is suppressed.

As shown in FIG. 3, the third side surface 45 includes a first partial side surface 45 a continuous with the first main surface 31, a second partial side surface 45 b continuous with the second main surface 33, a first partial side surface 45 a and a second portion. And a third partial side surface 45c connecting the side surface 45b.
The first partial side surface 45a of the third side surface 45 is curved to be convex in the (+ X, −Y ′) direction while being inclined in the (+ X, + Y ′) direction from the end portion on the + X direction side of the first main surface 31. It is formed with a surface. The first partial side surface 45a is uniformly formed in the Z ′ direction. Since the first partial side surface 45 a is formed by a curved surface that is continuous with the first main surface 31, the ridge line at the connection portion 31 b between the first partial side surface 45 a and the first main surface 31 is blunt. In the present embodiment, since the first partial side surface 45a and the first main surface 31 are continuous, there is no ridgeline.
The second partial side surface 45b of the third side surface 45 is curved to be convex in the (+ X, + Y ′) direction while being inclined in the (+ X, −Y ′) direction from the end portion of the second main surface 33 on the + X direction side. It is formed with a surface. The second partial side surface 45b is uniformly formed in the Z ′ direction. Since the second partial side surface 45 b is formed by a curved surface continuous with the second main surface 33, the ridge line at the connection portion 33 b between the second partial side surface 45 b and the second main surface 33 is blunt. In the present embodiment, since the second partial side surface 45b and the second main surface 33 are continuous, there is no ridgeline.
The third partial side surface 45c of the third side surface 45 is a curved surface that is connected to the + X direction side end of the first partial side surface 45a and the + X direction side end of the second partial side surface 45b and is convex in the + X direction. Is formed. The third partial side surface 45c is formed uniformly in the Z ′ direction.
By forming the third side surface 45 in this way, all the ridge lines of the third side surface 45 become dull, and therefore, spurious oscillation that occurs at the end of the piezoelectric vibrating piece 10 on the + X direction side is suppressed.

The fourth side surface 47 connects the first partial side surface 47a continuous with the first main surface 31, the second partial side surface 47b continuous with the second main surface 33, and the first partial side surface 47a and the second partial side surface 47b. Three-part side surface 47c.
The first partial side surface 47a of the fourth side surface 47 protrudes in the (−X, −Y ′) direction while being inclined in the (−X, + Y ′) direction from the end portion of the first main surface 31 on the −X direction side. It is formed with a curved surface. The first partial side surface 47a is uniformly formed in the Z ′ direction. Since the first partial side surface 47 a is formed by a curved surface continuous with the first main surface 31, the ridge line at the connection portion 31 c between the first partial side surface 47 a and the first main surface 31 is blunt. In the present embodiment, since the first partial side surface 47a and the first main surface 31 are continuous, there is no ridgeline.
The second partial side surface 47b of the fourth side surface 47 protrudes in the (−X, + Y ′) direction while being inclined in the (−X, −Y ′) direction from the end portion on the −X direction side of the second main surface 33. It is formed with a curved surface. The second partial side surface 47b is uniformly formed in the Z ′ direction. Since the second partial side surface 47 b is formed by a curved surface continuous with the second main surface 33, the ridge line at the connection portion 33 c between the second partial side surface 47 b and the second main surface 33 is blunt. In the present embodiment, since the second partial side surface 47b and the second main surface 33 are continuous, there is no ridgeline.
The third partial side surface 47c of the fourth side surface 47 is connected to the end portion on the −X direction side of the first partial side surface 47a and the end portion on the −X direction side of the second partial side surface 47b, and is convex in the −X direction. It is formed with a curved surface. The third partial side surface 47c is formed uniformly in the Z ′ direction.
By forming the fourth side surface 47 in this way, all the ridge lines of the fourth side surface 47 become dull, and therefore, spurious oscillation that occurs at the −X direction end of the piezoelectric vibrating piece 10 is suppressed.

  At this time, the maximum value of the projection widths PX and PZ ′ of the side surface 40 as viewed from the thickness direction of the piezoelectric vibrating piece 10 shown in FIG. 1 is the distance between the first main surface 31 and the second main surface 33 shown in FIG. The side surface 40 is formed so as to be smaller than twice the minimum value of T. Thereby, the 1st excitation electrode 51 and the 2nd excitation electrode 53 can be formed in a wider area | region, and CI value can be reduced.

As described above, the piezoelectric vibrating piece 10 according to the present embodiment is formed by AT cutting, and has the pair of main surfaces 30 and the side surfaces 40. The pair of main surfaces 30 are flat surfaces, and the side surfaces are side surfaces. At least a part of 40 is formed by a curved surface connected to at least one of the pair of main surfaces 30.
According to the present embodiment, since the piezoelectric vibrating piece 10 has a pair of main surfaces 30 formed as flat surfaces, the first excitation electrode 51 and the second excitation electrode 53 are arranged in a wide area in the main surface 30. Can be formed, and an increase in CI value can be suppressed. Further, since at least a part of the side surface 40 is formed by a curved surface continuous with one main surface, the one main surface and the side surface 40 are smoothly connected as compared with the case where the side surface 40 is formed by a slope. The ridge lines at the connection parts on both sides become dull. As a result, the reflection of vibration transmitted to the connecting portion without being sufficiently attenuated is reduced, and spurious oscillation is suppressed. Therefore, a piezoelectric vibrating piece having excellent vibration characteristics can be obtained.

Further, in the piezoelectric vibrating piece 10 of the present embodiment, the maximum value of the projection widths PX and PZ ′ of the side surface 40 viewed from the thickness direction of the piezoelectric vibrating piece 10 is 2 which is the minimum value of the interval T between the pair of main surfaces 30. It is characterized by being smaller than twice.
According to this configuration, since the area of the main surface 30 of the piezoelectric vibrating piece 10 can be formed wide, the first excitation electrode 51 and the second excitation electrode 53 can be formed in a wider region, and the CI value can be reduced. Therefore, a piezoelectric vibrating piece with more excellent vibration characteristics can be obtained.

The piezoelectric vibrator 1 according to this embodiment includes a piezoelectric vibrating piece 10.
According to this embodiment, since the piezoelectric vibrator 1 includes the piezoelectric vibrating piece 10 having excellent vibration characteristics described above, a piezoelectric vibrator having excellent vibration characteristics can be obtained.

(First Embodiment, Manufacturing Method of Piezoelectric Vibrating Piece)
Next, a manufacturing method of the piezoelectric vibrating piece according to the first embodiment will be described.
5 to 10 are process diagrams illustrating the method of manufacturing the piezoelectric vibrating piece according to the first embodiment, and are cross-sectional views corresponding to FIG.

  In the method of manufacturing the piezoelectric vibrating piece 10 according to the present embodiment, the first mask forming step of forming the first mask 81a of the outer shape pattern of the piezoelectric vibrating piece 10 on the surface of the wafer S, and the wafer S via the first mask 81a. An outer shape forming step of forming an outer shape pattern of the piezoelectric vibrating piece 10 and a curved surface forming step of forming a curved surface connected to at least one of the pair of main surfaces 30 on the side surface 40 by wet etching the wafer S. .

  First, a rough Lambert stone crystal is AT-cut and lapped to a constant thickness and then roughly processed, and then the work-affected layer is removed by etching, followed by mirror polishing such as polishing. A wafer S is prepared.

(First mask forming step)
Next, the first mask forming process will be described. As shown in FIG. 5, an etching protection film 81 and a photoresist film 83 are formed on both surfaces of the wafer S, respectively.
The etching protective film 81 has resistance to etching of the wafer S made of quartz described later. For example, a chromium (Cr) metal layer having a thickness of several tens of nm and a gold (Au) metal layer having a thickness of several tens of nm are sequentially laminated.
In this step, first, an etching protective film 81 is 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 81 by a spin coating method or the like to form a photoresist film 83.
As the 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, as shown in FIGS. 6 and 7, a first mask 81 a having an outer pattern of the piezoelectric vibrating piece 10 is formed on the surface of the wafer S.
Specifically, first, one surface of the wafer S on which the etching protective film 81 and the photoresist film 83 are formed is exposed using a photomask on which the outer shape pattern of the piezoelectric vibrating piece 10 is formed. Similarly, the other surface of the wafer S is exposed using a photomask on which the outer shape pattern of the piezoelectric vibrating piece 10 is formed. Then, the photoresist film 83 formed on both surfaces of the wafer S is collectively developed. As a result, as shown in FIG. 6, the external pattern 83 a of the piezoelectric vibrating piece 10 is formed on the photoresist film 83 formed on both surfaces of the wafer S.
Next, the etching protection film 81 formed on both surfaces of the wafer S is etched using the photoresist film 83 on which the outer shape pattern 83a of the piezoelectric vibrating piece 10 is formed as a mask, and an unmasked etching protection film 81 is formed. Selectively remove. As a result, as shown in FIG. 7, the first mask 81 a having the outer shape pattern of the piezoelectric vibrating piece 10 is formed on both surfaces of the wafer S.
For the etching process of the etching protection film 81, a wet etching method in which the wafer S on which the etching protection film 81 and the photoresist film 83 are formed is immersed in a chemical solution can be used. For example, when the etching protection film 81 is made of gold (Au), etching can be performed using iodine as a chemical solution.

(Outline forming process)
Next, the outer shape forming process will be described. As shown in FIG. 8, the wafer S is etched through the first mask 81 a to form the outer shape pattern of the piezoelectric vibrating piece 10.
The wafer S can be etched by using a wet etching method in which the wafer S on which the first mask 81a is formed is immersed in a chemical solution. For example, etching can be performed using hydrofluoric acid as a chemical solution, and the etching time is about 3 hours. Thereby, the outer shape of the piezoelectric vibrating piece 10 is formed. At this time, the first side face 41 on the + Z ′ direction side and the second side face 43 on the −Z ′ direction side of the side face 40 of the piezoelectric vibrating piece 10 are formed by the R face among the natural crystal faces of the quartz crystal.

  Next, as shown in FIG. 9, the etching protection film 81 and the photoresist film 83 are removed. Thereby, the piezoelectric plate 20 is in a state where the pair of main surfaces 30 and the side surfaces 40 are exposed. The removal of the photoresist film 83 may be performed after the etching processing of the etching protective film 81 described above (before the outer shape forming step).

(Curved surface forming process)
Next, the curved surface forming process will be described. As shown in FIG. 10, the wafer S is wet-etched to form a curved surface on the side surface 40 that continues to at least one of the pair of main surfaces 30.
This wet etching process can be performed in the same manner as the wet etching process for forming the outer shape pattern of the piezoelectric vibrating piece 10 described above. At this time, the etching time is about 30 minutes, for example.

  As described above, when wet etching is performed in a state in which the mask in the vicinity of the connection portion between the main surface 30 and the side surface 40 is removed, the natural crystal plane other than the m plane becomes dull in the ridge lines other than the ridge line with the m plane. It is etched and changes into a convex curved surface. Note that the imaginary line shown in FIG. 10 represents the m-plane of the crystal crystal, and the connecting portions 31d and 33d are ridge lines with the m-plane, so that the ridge lines remain sharp in the manufacturing method of this embodiment.

  Finally, the piezoelectric vibrating piece 10 is obtained by forming the excitation electrode, the mount electrode, the routing wiring, the mount back electrode, and the connection portion on the surface of the piezoelectric plate 20.

As described above, in the method of manufacturing the piezoelectric vibrating piece 10 according to the present embodiment, the first mask forming step of forming the first mask 81a of the outer shape pattern of the piezoelectric vibrating piece 10 on the surface of the wafer S, and the first mask 81a The wafer S is etched to form an outer shape pattern of the piezoelectric vibrating piece 10, and the wafer S is wet etched to form a curved surface connected to at least one of the pair of main surfaces 30 on the side surface 40. A curved surface forming step.
According to the present embodiment, by performing wet etching on the piezoelectric vibrating piece 10 having the outer shape pattern, the ridge line between one main surface and the side surface 40 is rounded, and the side surface 40 changes to a curved surface. Therefore, a piezoelectric vibrating piece having a curved surface continuous with one main surface can be easily manufactured.

(First Embodiment, First Modification, Piezoelectric Vibrating Piece)
Next, a piezoelectric vibrating piece according to a first modification of the first embodiment will be described.
FIG. 11 is a plan view of a piezoelectric vibrating piece according to a first modification of the first embodiment. FIG. 12 is an explanatory diagram of a piezoelectric vibrating piece according to a first modification of the first embodiment, and is a cross-sectional view taken along line XII-XII in FIG.

  11 and 12, the piezoelectric vibrating piece 10a differs from the first embodiment shown in FIGS. 1 to 3 in that the piezoelectric vibrating piece 10a has convex portions on the first main surface 31 and the second main surface 33. ing. In addition, detailed description is abbreviate | omitted about the part which becomes the structure similar to 1st Embodiment shown in FIGS.

As shown in FIGS. 11 and 12, the piezoelectric vibrating piece 10 a has the first convex portion 21 on the first main surface 31.
The first convex portion 21 has a so-called mesa shape formed integrally with the piezoelectric plate 20. The 1st convex part 21 is formed in the Y 'direction view rectangular shape. The first convex portion 21 is a central portion of the first main surface 31 and is formed at a position that does not overlap the first mount back electrode 65 and the second mount back electrode 67. The top surface 21 a of the first convex portion 21 is formed in a planar shape parallel to the first main surface 31.
The side surface of the first convex portion 21 is formed by a natural crystal surface of a quartz crystal. Of the side surfaces of the first convex portion 21, the side surface 21 b formed on the + Z ′ direction side is formed by the m-plane (and r-plane) of the crystal crystal and has an inner angle of about 150 with the top surface 21 a that is the XZ ′ plane. Degree. Further, among the side surfaces of the first convex portion 21, the side surface 21c formed on the −Z ′ direction side is formed by the R plane of the crystal crystal, and the inner angle with the top surface 21a is about 93 degrees.

In addition, the piezoelectric vibrating piece 10 a has the second convex portion 23 on the second main surface 33.
The second convex portion 23 has a so-called mesa shape formed integrally with the piezoelectric plate 20. The 2nd convex part 23 is formed in the Y 'direction view rectangular shape. The second convex portion 23 is a central portion of the second main surface 33 and is formed at a position that does not overlap the mount electrode 55. The top surface 23 a of the second convex portion 23 is formed in a planar shape parallel to the second main surface 33.
The side surface of the second convex portion 23 is formed by a natural crystal surface of a crystal crystal. Of the side surfaces of the second convex portion 23, the side surface 23 b formed on the −Z ′ direction side is formed by the m-plane (and r-plane) of the crystal crystal, and the inner angle with the top surface 23 a that is the XZ ′ plane is about It will be 150 degrees. Further, among the side surfaces of the second convex portion 23, the side surface 23c formed on the + Z ′ direction side is formed by the R plane of the quartz crystal, and the internal angle with the top surface 23a is about 93 degrees.

  The first excitation electrode 51 is formed on the top surface 21 a of the first convex portion 21, and the second excitation electrode 53 is formed on the top surface 23 a of the second convex portion 23. In this way, by forming the first convex portion 21 and the second convex portion 23, and the first excitation electrode 51 and the second excitation electrode 53, vibration energy can be confined with high accuracy in the central portion of the piezoelectric vibrating piece 10a. In addition, the vibration characteristics of the piezoelectric vibrating piece 10a can be further improved.

  In the present modification, the second routing wiring 59 is formed on the side surface 23 b of the second convex portion 23. Since the inner angle of the side surface 23b with respect to the top surface 23a of the second convex portion 23 is an obtuse angle, the occurrence of disconnection of the second lead wiring 59 in the ridge line portion can be suppressed.

As described above, the piezoelectric vibrating piece 10a according to this modification has a protrusion on the main surface 30.
According to this configuration, vibration energy can be confined in the first convex portion 21 and the second convex portion 23, so that a piezoelectric vibrating piece with more excellent vibration characteristics can be obtained.

(First Embodiment, First Modification, Method for Manufacturing Piezoelectric Vibrating Piece)
Next, a manufacturing method of the piezoelectric vibrating piece according to the first modification of the first embodiment will be described.
13-17 is process drawing explaining the manufacturing method of the piezoelectric vibrating piece which concerns on the 1st modification of 1st Embodiment, Comprising: It is sectional drawing of the part corresponded in FIG. In addition, since it becomes the same as that of the manufacturing method of 1st Embodiment until the external shape formation process corresponded to FIGS. 5-9, detailed description is abbreviate | omitted.

  The method for manufacturing the piezoelectric vibrating piece 10a according to the present modification is a method for manufacturing the piezoelectric vibrating piece 10a having a convex portion on the main surface 30, and the outer shape pattern of the convex portion is formed on the surface of the wafer S after the outer shape forming step. A second mask forming step for forming the two masks 91a, and a convex portion forming step for wet-etching the wafer S through the second mask 91a to form an external pattern of the convex portions. The curved surface forming step is performed by wet etching the wafer S in the convex portion forming step.

(Second mask forming step)
First, the second mask forming process will be described. As shown in FIG. 13, an etching protection film 91 and a photoresist film 93 are formed on both surfaces of the wafer S on which the outer shape of the piezoelectric vibrating piece 10a is formed. The material and forming method of the etching protection film 91 and the photoresist film 93 are the same as those of the etching protection film 81 and the photoresist film 83 in the first embodiment.

Next, as shown in FIGS. 14 and 15, a second mask 91 a having an outer pattern of the first and second protrusions is formed on the surface of the wafer S.
Specifically, first, one surface of the wafer S on which the etching protective film 91 and the photoresist film 93 are formed is exposed using a photomask on which an outer shape pattern of the first convex portion is formed. Similarly, the other surface of the wafer S is exposed using a photomask on which an outer shape pattern of the second convex portion is formed. Then, the photoresist films 93 formed on both surfaces of the wafer S are collectively developed. As a result, as shown in FIG. 14, the external pattern 93a of the first convex portion and the second convex portion is formed on the photoresist film 93 formed on both surfaces of the wafer S.
Next, the etching protection film 91 formed on both surfaces of the wafer S is etched using the photoresist film 93 on which the outer pattern 93a of the first and second protrusions is formed as a mask, and is not masked. The etching protective film 91 is selectively removed. As a result, as shown in FIG. 15, the second mask 91a having the outer pattern of the first and second convex portions is formed on both surfaces of the wafer S. Etching of the etching protective film 91 is performed in the same manner as the etching protective film 81 in the first embodiment. Note that the second mask 91a may be formed from the etching protective film 81 without removing the etching protective film 81 after the outer shape forming step.

(Projection forming process)
Next, a convex part formation process is demonstrated. As shown in FIG. 16, the wafer S is wet-etched through the second mask 91a to form a convex outer shape pattern.
The wafer S can be etched by using a wet etching method in which the wafer S on which the second mask 91a is formed is immersed in a chemical solution. Similar to the curved surface forming step of the first embodiment, for example, etching can be performed using hydrofluoric acid as a chemical solution. The etching time is about 30 minutes. Thereby, the 1st convex part 21 and the 2nd convex part 23 are formed. At this time, since the vicinity of the connecting portion between the pair of main surfaces 30 and the side surface 40 of the piezoelectric plate 20 is exposed, the wet etching at the time of forming the first convex portion 21 and the second convex portion 23 causes the side surface 40 to be exposed. A curved surface is formed simultaneously.

  Next, as shown in FIG. 17, the etching protection film 91 and the photoresist film 93 are removed. Thereby, the piezoelectric plate 20 having the first convex portion 21 and the second convex portion 23 is obtained. Note that the removal of the photoresist film 93 may be performed after the etching processing of the etching protective film 91 described above (before the convex portion forming step).

  Finally, the piezoelectric vibrating reed 10a is obtained by forming the excitation electrode, the mount electrode, the routing wiring, the mount back electrode, and the connection portion on the surface of the piezoelectric plate 20.

As described above, the method for manufacturing the piezoelectric vibrating piece 10a of the present modification is a method for manufacturing the piezoelectric vibrating piece 10a having the convex portion on the main surface 30, and the convex portion is formed on the surface of the wafer S after the outer shape forming step. A second mask forming step of forming a second mask 91a having an outer shape pattern; and a convex portion forming step of wet-etching the wafer S via the second mask 91a to form an outer shape pattern of the convex portion. The curved surface forming step is performed by performing wet etching on the wafer S in the convex portion forming step.
According to this modification, the curved surface of the side surface 40 can be formed simultaneously with the formation of the convex portion on the main surface 30 of the piezoelectric vibrating piece 10a. Therefore, a curved surface connected to one of the main surfaces can be easily formed without adding a special process to the piezoelectric vibrating piece 10a having a convex portion on the main surface 30.

(Second Embodiment, Piezoelectric Vibrating Piece)
Next, the piezoelectric vibrating piece according to the second embodiment will be described.
18 is an explanatory diagram of the piezoelectric vibrating piece according to the second embodiment, and is a cross-sectional view of a portion corresponding to the line II-II in FIG.

  In the first embodiment shown in FIGS. 1 to 3, the side surface 40 of the piezoelectric vibrating piece 10 is formed only by a curved surface, but in the second embodiment shown in FIG. 18, the side surface 140 is formed by a curved surface and a slope. It is different in point. In addition, detailed description is abbreviate | omitted about the part which becomes the structure similar to 1st Embodiment shown in FIGS.

  As shown in FIG. 18, the piezoelectric vibrating piece 110 of the present embodiment has a side surface 140 formed of a plurality of partial side surfaces including a curved surface, and a partial side surface connected to the other of the pair of main surfaces 30 is the other main surface. It is formed of a slope whose interior angle with the surface is an obtuse angle.

The side surface 140 includes a first side surface 141 formed on the side on the + Z ′ direction side, a second side surface 143 formed on the side on the −Z ′ direction side, and the + X direction among the four outer peripheral sides of the piezoelectric vibrating piece 110. A third side surface (not shown) formed on the side edge, and a fourth side surface (not shown) formed on the side on the −X direction side.
The first side surface 141 includes a first partial side surface 141 a that is connected to the first main surface 31, and a second partial side surface 141 b that is continuous with the second main surface 33. The first partial side surface 141a of the first side surface 141 is inclined in the (+ Y ′, + Z ′) direction from the end portion on the + Z ′ direction side of the first main surface 31, and the (−Y ′, + Z ′) direction is modulo. It is formed with the slope which makes a line direction. The first partial side surface 141a is uniformly formed in the X direction. In the present embodiment, the first partial side surface 141a of the first side surface 141 is formed by an m-plane of quartz crystal, and an internal angle with the first main surface 31 that is the XZ ′ plane is about 150 degrees. The second partial side surface 141b of the first side surface 141 is inclined in the (−Y ′, + Z ′) direction from the end portion on the + Z ′ direction side of the second main surface 33, and on the + Z ′ direction side of the first partial side surface 141a. Connected to the end. The second partial side surface 141b is formed of a curved surface that is convex in the (+ Y ′, + Z ′) direction. The second partial side surface 141b is formed uniformly in the X direction. Since the second partial side surface 141b is formed by a curved surface continuous with the second main surface 33, the ridge line at the connection portion 33a between the second partial side surface 141b and the second main surface 33 is blunt. In the present embodiment, since the second partial side surface 141b and the second main surface 33 are continuous, there is no ridgeline.

  Thus, by forming the first side surface 141 with a curved surface and an inclined surface, the end portion on the + Z ′ direction side of the piezoelectric vibrating piece 110 can be formed to taper toward the center in the thickness direction. . Thereby, compared with the case where the first side surface 141 is formed by only one curved surface, the end portion on the + Z ′ direction side of the piezoelectric vibrating piece 110 becomes thinner, so that vibration transmitted to the end portion can be sufficiently damped. It is possible to improve the accuracy of confining vibration energy in the center. In addition, since the cross-sectional shape of the end portion on the + Z ′ direction side of the piezoelectric vibrating piece 110 improves the symmetry in the thickness direction of the piezoelectric vibrating piece 110, it is possible to suppress an increase in the intensity of (thickness) secondary vibration. Furthermore, by forming the inclined surface with the m-plane of the crystal crystal, it is possible to realize a tapered shape in a sectional view at the end on the + Z ′ direction side of the piezoelectric vibrating piece 110 with a gentler inclination. As a result, the attenuation rate of vibration transmitted to the end portion of the piezoelectric vibrating piece 110 on the + Z ′ direction side is increased, and the accuracy of confining vibration energy in the central portion is further increased.

  The second side surface 143 includes a first partial side surface 143 a continuous with the first main surface 31 and a second partial side surface 143 b connected to the second main surface 33. The first partial side surface 143a of the second side surface 143 is inclined in the (+ Y ′, −Z ′) direction from the end portion on the −Z ′ direction side of the first main surface 31 (−Y ′, −Z ′). It is formed with a curved surface that is convex in the direction. The first partial side surface 143a is formed uniformly in the X direction. Since the first partial side surface 143a is formed as a curved surface continuous with the first main surface 31, the ridge line at the connection portion 31a between the first partial side surface 143a and the first main surface 31 is blunt. In the present embodiment, since the first partial side surface 143a and the first main surface 31 are continuous, there is no ridgeline. The second partial side surface 143b of the second side surface 143 is inclined in the (−Y ′, −Z ′) direction from the end portion of the second main surface 33 on the −Z ′ direction side, and −Z ′ of the first partial side surface 143a. It is connected to the end on the direction side. The second partial side surface 141b is formed by a slope whose normal direction is the (+ Y ′, −Z ′) direction. The second partial side surface 141b is formed uniformly in the X direction. In the present embodiment, the second partial side surface 143b of the second side surface 143 is formed by the m-plane of the crystal crystal, and the internal angle with the second main surface 33 that is the XZ ′ plane is about 150 degrees.

  Thus, by forming the second side surface 143 by a slope formed by a curved surface and an m-plane, for the same reason as the first side surface 141, the accuracy of confining vibration energy in the center can be improved, and (thickness) An increase in the intensity of the secondary vibration can be suppressed.

  Moreover, the 3rd side surface and 4th side surface which are not shown in figure are formed by the three partial side surfaces each formed by the curved surface similarly to 1st Embodiment shown in FIG. Therefore, similarly to the first side surface 141 and the second side surface 143 in the present embodiment, the third side surface and the fourth side surface are tapered in cross section. Thereby, for the same reason as the first side surface 141 and the second side surface 143, it is possible to improve the accuracy of confining the vibration energy in the central portion, and to suppress the increase in the intensity of the (thickness) secondary vibration.

As described above, the piezoelectric vibrating piece 110 according to the present embodiment has the side surface 140 formed of a plurality of partial side surfaces including a curved surface, and the partial side surface connected to the other of the pair of main surfaces 30 is in contact with the other main surface. It is formed by the slope whose interior angle becomes an obtuse angle.
According to this configuration, the partial side surface connected to the other main surface is formed as an inclined surface whose interior angle with the other main surface is an obtuse angle, so that the end portion of the piezoelectric vibrating piece 110 is disposed in the thickness direction. It can be formed in a shape that tapers toward the center. Thereby, compared with the case where the side surface 140 is formed by only one curved surface, the end portion of the piezoelectric vibrating piece 110 is thinned, so that vibration transmitted to the end portion can be sufficiently attenuated, and vibration energy is transmitted to the central portion. The accuracy of being trapped in can be improved. In addition, since the cross-sectional shape of the end portion of the piezoelectric vibrating piece 110 improves the symmetry in the thickness direction, an increase in the intensity of the secondary vibration can be suppressed. Therefore, a piezoelectric vibrating piece with more excellent vibration characteristics can be obtained.

In addition, the piezoelectric vibrating piece 110 of the present embodiment is characterized in that the inclined surface is formed by an m-plane of a crystal crystal.
According to this configuration, the slope formed by the m-plane of the crystal crystal is formed at an internal angle of about 150 degrees with the main surface 30 of the AT vibrating piece, so that the end portion of the piezoelectric vibrating piece 110 is tapered in a sectional view. Can be realized with a gentler slope. Thereby, the attenuation rate of the vibration transmitted to the end portion of the piezoelectric vibrating piece 110 is increased, and the confinement accuracy of the vibration energy in the central portion is further increased. Therefore, a piezoelectric vibrating piece with more excellent vibration characteristics can be obtained.

Furthermore, the piezoelectric vibrating piece 110 of the present embodiment is characterized in that all the side surfaces 140 have at least curved surfaces.
According to this configuration, the vibration transmitted to any end portion of the piezoelectric vibrating piece 110 can be sufficiently damped, and the confinement accuracy of the vibration energy in the central portion is further increased. Therefore, a piezoelectric vibrating piece with more excellent vibration characteristics can be obtained.

(Second Embodiment, Manufacturing Method of Piezoelectric Vibrating Piece)
Next, a method for manufacturing the piezoelectric vibrating piece according to the second embodiment will be described.
19 to 23 are process diagrams illustrating a method for manufacturing a piezoelectric vibrating piece according to the second embodiment, and are cross-sectional views of a portion corresponding to FIG. Note that the steps up to the step of forming the etching protective film 181 and the photoresist film 183 corresponding to FIG. 5 are the same as those in the manufacturing method of the first embodiment, and thus detailed description thereof is omitted.

First, as shown in FIGS. 19 and 20, a first mask 181 a having an outer pattern of the piezoelectric vibrating piece 110 is formed on the surface of the wafer S.
Specifically, first, an outer pattern 183 a of the piezoelectric vibrating piece 110 is formed on the photoresist film 183. At this time, the external patterns 183a on both surfaces of the wafer are formed so as to be shifted from each other by a predetermined amount in the Z ′ direction.
Next, the etching protection film 181 formed on both surfaces of the wafer S is etched using the photoresist film 183 on which the outer shape pattern 183a of the piezoelectric vibrating piece 110 is formed as a mask. Thereby, as shown in FIG. 20, the first mask 181 a having the outer shape pattern of the piezoelectric vibrating piece 110 is formed on both surfaces of the wafer S.
The etching protective film 181 and the photoresist film 183 are processed in the same manner as the etching protective film 81 and the photoresist film 83 in the first embodiment.

Next, as shown in FIG. 21, the wafer S is etched through the first mask 181 a to form the outer shape pattern of the piezoelectric vibrating piece 110.
Etching of the wafer S is performed in the same manner as the outer shape forming process of the first embodiment. At this time, due to the etching anisotropy of the crystal, the first side surface 141 on the + Z ′ direction side and the second side surface 143 on the −Z ′ direction side among the side surfaces of the piezoelectric plate 20 are m of the crystal crystal inclined at different angles. Two natural crystal planes, a plane and an R plane, are formed. Specifically, m-planes appear on the first partial side surface 141 a of the first side surface 141 and the second partial side surface 143 b of the second side surface 143, and the second partial side surface 141 b of the first side surface 141 and the second side surface 143 of the second side surface 143. An R surface appears on the one-part side surface 143a.

Incidentally, in the first embodiment shown in FIG. 7, the first masks 81a on both surfaces of the wafer are formed so as to overlap when viewed in the Y ′ direction. In this case, when the etching proceeds and the wafer in the non-mask portion penetrates, the inclination angle and the etching rate of the m-plane and the R-plane are different, so that the slope formed by the m-plane and the slope formed by the R-plane are mutually It is formed at a position that is not directly connected. In the first embodiment, in order to eliminate the step formed by the deviation of the two slopes, wet etching is performed until the side face 40 becomes a single slope formed by the R plane even after the wafer is penetrated as shown in FIG. Continue.
On the other hand, in the present embodiment, since the first mask 181a is formed by shifting by a predetermined amount in the Z ′ direction, the first mask 181a is formed on the m plane when both sides of the wafer are wet etched and the non-mask portion penetrates. The formed slope and the slope formed by the R plane are directly connected.

  Next, as shown in FIG. 22, the etching protection film 181 and the photoresist film 183 are removed. The removal method is performed in the same manner as in the first embodiment.

Next, as shown in FIG. 23, the wafer S is wet-etched. Thereby, a curved surface connected to at least one of the pair of main surfaces 30 and a slope connected to the other are formed on the side surface of the piezoelectric plate 20.
This wet etching process is performed in the same manner as the curved surface forming process of the first embodiment.

  As described above, by wet etching the side surfaces formed by the m-plane and the R-plane, the ridge line other than the connection portion with the m-plane becomes dull in the connection portion between the main surface 30 and the slope or the slope and the slope. Etching proceeds as described above. That is, as shown in FIGS. 22 and 23, the connection part 31a between the first partial side surface 143a of the second side surface 143 and the first main surface 31 and the second partial side surface 141b of the first side surface 141 that are not connected to the m-plane. Only the ridgeline of the connecting portion 33a between the first main surface 33 and the second main surface 33 becomes dull. Thereby, the piezoelectric vibrating piece 110 whose side surface is formed by a curved surface and a slope can be manufactured.

The present invention is not limited to the embodiment described above.
For example, in the piezoelectric vibrating piece of the above embodiment, the length in the Z ′ direction is longer than the length in the X direction, but the length in the X direction is longer than the length in the Z ′ direction. It may be formed.

  DESCRIPTION OF SYMBOLS 1 ... Piezoelectric vibrator 10, 10a, 110 ... Piezoelectric vibration piece 21 ... 1st convex part (convex part) 23 ... 2nd convex part (convex part) 31 ... 1st main surface (main surface) 33 ... 2nd main surface (Main surface) 41, 141 ... 1st side surface (side surface) 43, 143 ... 2nd side surface (side surface) 45 ... 3rd side surface (side surface) 47 ... 4th side surface (side surface) 81 ... 1st mask 83 ... 2nd mask 141a ... First partial side surface (partial side surface) of the first side surface 141b ... Second partial side surface (partial side surface) of the first side surface 143a ... First partial side surface (partial side surface) of the second side surface 143b ... Second of the second side surface Partial side surface (partial side surface) S ... Wafer T ... Distance between a pair of main surfaces PX, PZ '... Projected width of side surface

Claims (6)

A piezoelectric vibrating piece formed by AT cut,
A first main surface on which a first protrusion is formed;
A second main surface on which a second convex portion is formed;
A first excitation electrode formed on the first main surface;
A second excitation electrode formed on the second main surface and a pair of mount electrodes;
On one side in the longitudinal direction, the first main surface and the second main surface are connected via a first curved surface that is directly connected only to the first main surface of the first main surface and the second main surface. ,
On the other side in the longitudinal direction, the first main surface and the second main surface are connected via a second curved surface that is directly connected only to the second main surface of the first main surface and the second main surface. ,And,
Slopes are formed on the side surfaces of the first and second convex portions in the longitudinal direction, and the slopes formed on the other side of the first convex portion rather than the slope formed on the one side are formed. The inclination angle with respect to the first main surface is gentler, and the inclined surface formed on the one side is inclined with respect to the second main surface than the inclined surface formed on the other side in the second convex portion. A piezoelectric vibrating piece characterized by having a gentle pitch.   2. The piezoelectric vibrating piece according to claim 1, wherein the X direction of the crystal axis is the short direction, the Y ′ direction is the thickness direction, and the Z ′ direction is the longitudinal direction.   3. The slope formed on the other side of the first convex portion and the slope formed on the one side of the second convex portion are m-planes of crystal crystals. The piezoelectric vibrating piece according to 1.   4. The slope formed on the one side in the first convex part and the slope formed on the other side in the second convex part are R faces of crystal crystals. The piezoelectric vibrating piece according to any one of the above.   A piezoelectric vibrator comprising the piezoelectric vibrating piece according to claim 1. A manufacturing method for manufacturing the piezoelectric vibrating piece according to any one of claims 1 to 4,
Forming a first mask having an external pattern of the piezoelectric vibrating piece on the surface of the wafer;
An outer shape forming step of etching the wafer through the first mask to form an outer shape pattern of the piezoelectric vibrating piece;
After the outer shape forming step, forming a second mask having an outer shape pattern of the first convex portion and the second convex portion;
Etching the wafer through the second mask to form a first convex portion, a second convex portion, a first curved surface, and a second curved surface;
A method of manufacturing a piezoelectric vibrating piece, comprising:

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