JP5122769B2 - Piezoelectric piece and piezoelectric piece forming method - Google Patents

Description

  The present invention relates to a piezoelectric piece used for an electronic component and a piezoelectric piece forming method.

  2. Description of the Related Art In recent years, electronic devices such as mobile communication devices such as portable information terminal devices have been reduced in size while incorporating various additional functions in addition to a simple call function. Accordingly, further miniaturization of electronic components used in the mobile communication device is required. Here, an angular velocity sensor element will be described as an example of an electronic component. In this angular velocity sensor element, the number of electrodes is larger than that of the crystal vibrating element, and as the number of axes increases, a large number of electrodes are arranged on a small piezoelectric piece (see, for example, Patent Document 1). When the piezoelectric piece used for the angular velocity sensor element is formed from artificial quartz, the piezoelectric piece is formed by, for example, forming a protective film on a piezoelectric wafer, forming a resist film thereon, and overlaying a mask that forms the outer shape of the piezoelectric piece. It is formed by exposure and wet etching. Furthermore, the piezoelectric wafer is formed by lambert processing the grown crystal body, thinly cutting it and performing thickness polishing to make the thickness uniform, and then shaping such as polishing and light etching. .

For example, as shown in FIG. 7, the piezoelectric arm 100 is connected to the base 2, a plurality of detection arms 3 extending radially from the base 2, and the excitation arm 4 connected to the end of the adjacent detection arm 3. When the piezoelectric piece is formed in the above-described process, a residue N is generated in the corner C formed by the detection arm portion 3 and the excitation arm portion 4, and the base portion 2 and the detection arm portion 3 Residue N is also generated in the formed corner C. In addition, an asymmetric residue N is generated in each of the base, the excitation arm, and the detection arm.
The residue N is generated so as to connect the side surface of the detection arm portion 3 and the side surface of the excitation arm portion 4 at the corner portion C, and to connect the side surface of the base portion 2 and the side surface of the detection arm portion 3 at the corner portion C. To occur.
In addition, if an excitation electrode, a detection electrode, etc. are provided in the predetermined part of this piezoelectric piece 100, it will become an inertial sensor element.
JP 2006-17538 A (paragraphs 0011 to 0035, FIG. 5)

However, when the piezoelectric piece 100 is formed by wet etching from the piezoelectric wafer, the crystal surface etching rate differs due to the influence of etching anisotropy, so that the outer shape of the piezoelectric piece 100 is perpendicular to the main surface of the piezoelectric wafer. Residue N is generated without being traced, and the outer shape (shape) of the piezoelectric piece 100 is asymmetric.
Such a residue N may be formed in a portion where the shape of the piezoelectric piece 100 becomes an acute angle, and vibration characteristics such as coupling with a spurious mode due to deterioration of vibration balance, deterioration of temperature characteristics, and reduction of Q value. It was a cause of worsening.

  Accordingly, an object of the present invention is to provide a piezoelectric piece and a piezoelectric piece forming method that solve the above-described problems and reduce the generation of residues.

In order to solve the above-described problem, the present invention includes a base, a plurality of detection arm portions extending radially around the base portion, and a plurality of excitation arm portions connected to the ends of the adjacent detection arm portions. A piezoelectric piece made of a piezoelectric material having n-fold symmetry, which is formed of an arcuate corner formed by the base and the detection arm, the detection arm and the excitation arm. An arcuate corner is formed by drilling with a drill .

Further, the present invention is a piezoelectric piece made of a piezoelectric material having n-fold symmetry, comprising a base, an excitation arm extending from one of the bases, and a detection arm extending from the other of the bases, characterized in that the internal corner portion of an arc shape formed between the base and the excitation arm portion, and the inner corner portion of an arc shape formed between the base and the detector arm portion is formed by drilling with a drill And

  Further, the present invention provides n-fold symmetry including a base, a plurality of detection arm portions extending radially around the base portion, and a plurality of excitation arm portions connected to the ends of the adjacent detection arm portions. A piezoelectric piece forming method for forming a piezoelectric piece made of a piezoelectric material having a shape of a crystal grown by a crystal growing device, and the base of the vibrating piece and the detection arm on the main surface of the crystal A drilling step of drilling a portion to be an entrance corner formed by the above and a portion to be an entrance corner formed by the detection arm portion and the excitation arm portion; and the drilled crystal body to the crystal body A plate-shaped body shaping step of slicing in parallel with the main surface of the plate-shaped body, and forming the plate-shaped body in the plate-shaped body so that the perforated portion of the plate-shaped body is the corner of the piezoelectric piece. And a piezoelectric piece forming step of forming the piezoelectric piece.

Further, the present invention provides n-fold symmetry including a base, a plurality of detection arm portions extending radially around the base portion, and a plurality of excitation arm portions connected to the ends of the adjacent detection arm portions. A piezoelectric piece forming method for forming a piezoelectric piece made of a piezoelectric material having a plate-like body shaping that is sliced at a predetermined angle in parallel to a main surface of a crystal grown by a crystal growth apparatus and shaped into a plate-like body process and arc shape formed by the inner corner portion become part of the arc shape formed by the base and the detector arm portion and the main surface of the plate-like body, and the detection arm section and the excitation arm portion A drilling step of drilling a portion to be a corner of the plate with a drill, and the plate-like body so that a portion of the plate-like body drilled with the drill becomes the arc-shaped corner of the piezoelectric piece. And a piezoelectric piece forming step of forming the piezoelectric piece.

  According to another aspect of the present invention, there is provided a piezoelectric element for forming a piezoelectric piece made of a piezoelectric material having n-fold symmetry, comprising a base, an excitation arm extending from one of the bases, and a detection arm extending from the other of the bases. A piece forming method, shaping a crystal grown by a crystal growing apparatus, a portion serving as a corner formed by the base and the excitation arm on the main surface of the crystal, and the base A perforating step for perforating a corner portion formed by the detection arm portion, and a plate shape for slicing the perforated crystal body parallel to the main surface of the crystal body and shaping it into a plate-like body A body shaping step, and a piezoelectric piece forming step of forming the piezoelectric piece on the plate-like body so that the perforated portion of the plate-like body becomes the corner of the piezoelectric piece. To do.

According to another aspect of the present invention, there is provided a piezoelectric element for forming a piezoelectric piece made of a piezoelectric material having n-fold symmetry, comprising a base, an excitation arm extending from one of the bases, and a detection arm extending from the other of the bases. It is a piece forming method, a plate-like body shaping step for shaping into a plate-like body by slicing at a predetermined angle parallel or parallel to the principal surface of the crystal grown by the crystal growth apparatus, and on the principal surface of the crystal Drilling to drill a portion that is an arc-shaped corner formed by the base and the excitation arm and a portion that is an arc-shaped corner formed by the base and the detection arm And a piezoelectric piece forming step of forming the piezoelectric piece on the plate-like body so that a portion drilled with the drill in the plate-like body becomes the arc-shaped corner of the piezoelectric piece. It is characterized by.

According to such a piezoelectric piece, a residue generated in the corner can be reduced as compared with the conventional one by punching the corner of the piezoelectric piece before etching.
Further, according to such a method for forming a piezoelectric piece, a residue generated in the corner can be reduced as compared with the prior art by punching a portion that becomes the corner before forming the piezoelectric piece.

  Next, the best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be described in detail with reference to the drawings as appropriate. A piezoelectric material having n-fold symmetry (for example, n = 3, 6, etc.) will be described as quartz having three-fold symmetry.

(First embodiment)
FIG. 1 is a plan view showing an example of a piezoelectric piece according to the first embodiment of the present invention. FIG. 2 is a perspective view showing an example of a crystal body. FIG. 3 is a plan view showing a state in which the crystal body is seen from the direction of arrow A in FIG. FIG. 4 is a diagram showing a state in which the shaped crystal is formed into a plate-like body. FIG. 5 is a diagram illustrating an example of a state where a piezoelectric piece is formed on a plate-like body.

As shown in FIG. 1, the piezoelectric piece 10 according to the first embodiment of the present invention includes a base portion 2, a plurality of detection arm portions 3 extending radially around the base portion 2, and the adjacent detection arm portions. A plurality of excitation arm portions 4 connected to the end portions 3 and 3 are provided.
In the piezoelectric piece 10 configured as described above, the corner portion C is formed by the base portion 2 and the detection arm portion 3, and the corner portion C is formed by the detection arm portion 3 and the excitation arm portion 4.

Here, the entering corner portion C refers to a corner portion (corner portion) formed to be recessed.
The corner C is provided in an arc shape by perforation. A drill is used for drilling.
Thereby, a minute through hole H (see FIG. 3) can be drilled in the crystal body K1 (see FIG. 2). By this perforation, the residue N generated at the corner C of the piezoelectric piece 10 can be reduced. The crystal body K1 is made of, for example, a Z-plate as-grown artificial crystal.

  Conventionally, when wet etching is performed, the residue N is connected to a crystal plane having a different etching rate at the corner C, and a lot of residue N is generated. However, the base 2 and the detection arm 3 In the portion formed by wet etching of the piezoelectric piece 10 by punching the entering corner portion C formed by the above and the entering corner portion C formed by the detection arm portion 3 and the excitation arm portion 4, Also, the residue N generated in the corner C can be reduced.

As described above, since the piezoelectric piece 10 according to the first embodiment of the present invention is configured, the residue N generated in the corner C can be reduced by drilling the corner C before wet etching. it can.
Specifically, when wet etching is performed in a state in which the portion to be the corner C of the piezoelectric piece 10 is perforated, when the thickness direction with a high etching rate is eroded first, the eroded portion is a perforated portion. The residue N is generated without being connected to the side surface of the detection arm portion 3 and the side surface of the excitation arm portion 4, and is generated without being connected to the side surface of the base portion 2 and the side surface of the detection arm portion 3. It becomes. If wet etching is continued in this state, the residue N generated on the side surface of the base 2, the residue N generated on the side surface of the detection arm portion 3, and the residue N generated on the side surface of the excitation arm portion 4 are not affected by the adjacent residues. As a result, the residue N that could not be eroded at the entrance corner C as in the prior art can be reduced.

  Next, a piezoelectric piece forming method of the piezoelectric piece 10 according to the first embodiment of the present invention will be described.

(Punching process)
A crystal grown by a crystal growth apparatus (not shown) is shaped (see FIG. 2), and a portion to be a corner C formed by the base 2 and the detection arm 3 on the main surface of the crystal; Then, a portion that becomes the corner C formed by the detection arm portion 3 and the excitation arm portion 4 is drilled with a drill.
Here, the crystal formed by the crystal growth apparatus (not shown) is a Z-plate as-grown artificial quartz, and in the grown state, the surface is non-uniform so as to wave (not shown). ). This non-uniform state is shaped into a crystalline body K1 (see FIG. 2) having a uniform surface by Lambert processing.
For example, the shape of the piezoelectric piece 10 to be finally provided is described in the crystal body K1, and a portion to be the corner C is drilled with a drill (see FIG. 3).

(Plate-shaped body shaping process)
The perforated crystal body K1 is sliced parallel to the main surface of the crystal body K1 and shaped into a plate-like body K2 (see FIG. 4).
Here, after the drilling is completed, the slice is cut (cut) in parallel with the main surface of the crystal body K1. By this slicing, a plurality of plate-like bodies K2 having a predetermined thickness are shaped from the crystal body K1 to obtain a piezoelectric wafer. In addition, after slicing, thickness polishing, polishing, and light etching are performed to make the thickness uniform, so that the plate-like body K2 having a smooth surface is obtained.

(Piezoelectric piece forming process)
The piezoelectric piece 10 is formed in the plate-like body K2 so that the through hole H (see FIGS. 3 and 4) drilled in the plate-like body K2 becomes the arc-shaped corner C of the piezoelectric piece 10 (see FIG. 5). .
Here, a protective film (not shown) is formed on the plate-like body K2, and a resist (not shown) is formed on the protective film. In this state, a mask describing the shape of the piezoelectric piece 10 is overlapped so that the through-hole H drilled with a drill becomes the arcuate corner C of the piezoelectric piece 10, and the plate shape is formed by an exposure apparatus (not shown). The body K2 is exposed. Thereafter, the plate-like body K2 is developed, the exposed metal film (protective film) is removed by etching, and the plate-like body K2 is wet-etched. Thereby, the shape of the piezoelectric piece 10 is provided in the plate-like body K2.

At this time, since the internal corner portion C of the arc shape of the piezoelectric element 10 caused many residue N than the other portion is drilled, wet etching while drilling a portion to be the internal corner portion C of the piezoelectric element 10 As a result, the thickness direction with a fast etching rate is eroded first, the eroded portion reaches the perforated portion, and the residue N is not connected to the side surface of the detection arm portion 3 and the side surface of the excitation arm portion 4. In addition, it occurs without being connected to the side surface of the base portion 2 and the side surface of the detection arm portion 3. If wet etching is continued in this state, the residue N generated on the side surface of the base 2, the residue N generated on the side surface of the detection arm portion 3, and the residue N generated on the side surface of the excitation arm portion 4 are not affected by the adjacent residues. As a result, the residue N that could not be eroded at the entrance corner C as in the prior art can be reduced.

  Thus, since the piezoelectric piece formation method of the piezoelectric piece 10 which concerns on 1st embodiment of this invention was comprised, the residue N which arises in the corner C can be reduced.

  An excitation electrode (not shown) is formed on the excitation arm portion 4 of the piezoelectric piece 10 according to the first embodiment of the present invention thus formed, and a detection electrode (not shown) is formed on the detection arm portion 3. For example, if it is used for an inertial sensor element, the shape of the piezoelectric piece 10 has symmetry regardless of the residue N at the corner portion C. Therefore, the shape of the piezoelectric piece 10 due to the residue N is asymmetric. By preventing the deterioration of the vibration balance due to the property, coupling with the spurious mode can be prevented, the temperature characteristics can be improved, and the inertial sensor element that improves the vibration characteristics such as increasing the Q value can be obtained.

As a modification, a piezoelectric piece forming step in which a perforating step is performed after the plate-shaped body shaping step is performed, and then wet etching is performed may be performed.
In this case, the plate body K2 may be formed by slicing the crystal body K1 at a predetermined angle.
In this way, piezoelectric pieces corresponding to various vibration modes can be formed.
Even if comprised in this way, since the corner is perforated, the same effects as in the first embodiment can be obtained.

(Second embodiment)
Next, the piezoelectric piece 20 according to the second embodiment of the present invention will be described.
FIG. 6 is a plan view showing an example of a piezoelectric piece according to the second embodiment of the present invention.

  The piezoelectric piece 20 according to the embodiment of the present invention includes a base 2, an excitation arm 4 extending from one of the bases 2, and a detection arm 3 extending from the other of the bases 2. This is different from the first embodiment.

For example, in the case of a piezoelectric fork with a tuning fork structure, an excitation arm that extends from one end of the base and a detection arm that extends from the other end of the base parallel to the excitation arm Composed.
Further, for example, in the case of an H-shaped piezoelectric piece, a pair of excitation arm portions extending in parallel from both end portions of the base portion, and extending from the other end portions of the base portion on the opposite side to the excitation arm portion. It comprises a pair of detection arms. In the present embodiment, a case where the piezoelectric piece 20 has an H-type structure will be described.

Thus, in the piezoelectric piece 20 having an H-shaped structure, the base portion 2 and the excitation arm portion 4 form an arc-shaped corner C, and the base 2 and the detection arm portion 3 form an arc-shaped corner C. Is formed. In the case of the piezoelectric piece 20 having the H-type structure, since the support portion S that supports the piezoelectric piece 20 is provided, the support portion S and the base portion 2 also form an arcuate corner C. Become.

In addition, as above-mentioned, the entrance corner part C means the corner part (corner part) formed concavely.
The corner C is provided in an arc shape by drilling with a drill . A drill or the like can be used for drilling. As a result, minute through holes can be drilled in the Lambertian processed crystal.
By this perforation, the residue N generated at the corner C of the piezoelectric piece 20 can be reduced.

It shall be drilled and the inner corner portion C of the arc shape formed by the base 2 and the detection arm section 3, and a reentrant portion C of the arc shape formed by the base 2 and the excitation arm portion 4 in a drill Thus, when wet etching is performed in a state in which the portion to be the corner C of the piezoelectric piece 20 is perforated, the thickness direction with the fast etching rate is eroded first, and the eroded portion reaches the perforated portion, and the residue N is generated without being connected to the side surface of the base portion 2 and the side surface of the detection arm portion 3, and is generated without being connected to the side surface of the base portion 2 and the side surface of the detection arm portion 3. If wet etching is continued in this state, the residue N generated on the side surface of the base 2, the residue N generated on the side surface of the detection arm portion 3, and the residue N generated on the side surface of the excitation arm portion 4 are not affected by the adjacent residues. As a result, the residue N that could not be eroded at the entrance corner C as in the prior art can be reduced.

  As described above, since the piezoelectric piece 20 according to the second embodiment of the present invention is configured, the residue N generated in the corner C can be reduced by drilling the corner C before etching. .

Next, a piezoelectric piece forming method of the piezoelectric piece 20 according to the second embodiment of the present invention will be described.
The piezoelectric piece forming method of the piezoelectric piece 20 according to the second embodiment of the present invention includes a drilling step, a plate-shaped body shaping step, and a piezoelectric piece forming step, as in the first embodiment.

(Punching process)
A crystal grown by a crystal growing device (not shown) is shaped, and a portion that becomes an arcuate corner C formed by the base 2 and the excitation arm 4 on the main surface of the crystal, and the base 2 And the detection arm portion 4 are used to drill a portion that becomes an arcuate corner portion C formed by a drill . In addition, when providing the support part S in the base 2, the part used as the circular arc shaped corner C formed by the base 2 and the support S is also drilled with a drill.

Here, the crystal formed by the crystal growing apparatus is an as-grown whose main surface is a Z plane, and in the grown state, the surface is non-uniform so as to wave, and this non-uniform state Is made uniform by Lambert processing and the surface is shaped flat. Then, for example, a mask describing the shape of the piezoelectric piece 20 to be finally provided is overlaid on the Lambert-processed crystal body, and a portion to become the corner C is drilled with a drill.

(Plate-shaped body shaping process)
The perforated crystal body is sliced parallel to the main surface of the crystal body and shaped into a plate-like body.

(Piezoelectric piece forming process)
The piezoelectric piece 20 is formed on the plate-like body so that the portion drilled by the drill in the plate-like body becomes the arcuate corner C of the piezoelectric piece 10.

  Thus, since the piezoelectric piece formation method of the piezoelectric piece 20 which concerns on 2nd embodiment of this invention was comprised, the residue which arises in the corner C can be reduced.

  An excitation electrode is formed on the excitation arm portion 4 of the piezoelectric piece 20 according to the second embodiment of the present invention formed as described above, and a detection electrode is formed on the detection arm portion 3, for example, in an inertial sensor element. If used, the shape of the piezoelectric piece 20 is symmetric regardless of the residue N at the corner portion C. Therefore, the spurious can be prevented by preventing the vibration balance from deteriorating due to the asymmetry of the shape of the piezoelectric piece due to the residue N. The inertial sensor element that prevents the coupling with the mode, improves the temperature characteristics, and improves the vibration characteristics such as increasing the Q value can be obtained.

As a modification, a piezoelectric piece forming step of performing a perforating step after performing a plate-shaped body shaping step and then performing wet etching may be performed.
In this case, the plate can be formed by slicing the crystal body at a predetermined angle.
In this way, piezoelectric pieces corresponding to various vibration modes can be formed.
Even if comprised in this way, since the crystal plane in which the etching rate in an entrance corner differs is annihilated by perforation, there exists an effect similar to 2nd embodiment.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. For example, the shape of the piezoelectric piece can be appropriately used as long as it has a shape in which a corner is formed, such as a tripod tuning fork structure or a king-shaped structure.
Further, when forming the shape of the piezoelectric piece, an image recognition device can be used for the outer shape of the piezoelectric piece based on the perforated through hole. For example, in a plate-like body provided with a through-hole, the external shape of the piezoelectric piece is grasped from a plurality of through-holes provided in a portion serving as a corner, and a protective film and a resist are provided. A shape of the piezoelectric piece may be formed by overlaying a mask along the shape of the grasped piezoelectric piece, exposing the mask, developing, and performing wet etching.

It is a top view which shows an example of the piezoelectric piece which concerns on 1st embodiment of this invention. It is a perspective view which shows an example of a crystal body. It is a top view which shows the state which pierced the crystal body seen from the A arrow direction in FIG. It is a figure which shows the state which made the shaped crystal body into a plate-shaped body. It is a figure which shows an example of the state which formed the piezoelectric piece in the plate-shaped object. It is a top view which shows an example of the piezoelectric piece which concerns on 2nd embodiment of this invention. It is a top view which shows an example of the conventional piezoelectric piece.

Explanation of symbols

10, 20 Piezoelectric piece 2 Base 3 Detection arm 4 Excitation arm C Corner corner K1 Crystal K2 Plate N N Residue

Claims (6)

Piezoelectric material made of a piezoelectric material having n-fold symmetry comprising a base, a plurality of detection arm portions extending radially around the base portion, and a plurality of excitation arm portions connected to the ends of the adjacent detection arm portions A piece,
And internal corner portion of an arc shape formed between the base portion and the detection arm section, the fact that the internal corner portion of the arc shape formed by the detection arm portion and the excitation arm portion is formed by drilling with a drill A piezoelectric piece characterized by A piezoelectric piece made of a piezoelectric material having n-fold symmetry comprising a base, an excitation arm extending from one of the bases, and a detection arm extending from the other of the bases,
Characterized in that the internal corner portion of an arc shape formed between the base and the excitation arm portion, and the inner corner portion of an arc shape formed between the base and the detector arm portion is formed by drilling with a drill Piezoelectric piece. Piezoelectric material made of a piezoelectric material having n-fold symmetry comprising a base, a plurality of detection arm portions extending radially around the base portion, and a plurality of excitation arm portions connected to the ends of the adjacent detection arm portions A piezoelectric piece forming method for forming a piece,
A crystal grown by a crystal growing apparatus is shaped, and a portion to be a corner formed by the base portion and the detection arm portion of the vibrating piece on the main surface of the crystal body, the detection arm portion and the A drilling step of drilling a portion to be a corner formed by the excitation arm portion;
A plate-shaped body shaping step of slicing the perforated crystal body in parallel with the main surface of the crystal body to form a plate-like body;
A piezoelectric piece forming step of forming the piezoelectric piece on the plate-like body so that the perforated portion of the plate-like body becomes the corner of the piezoelectric piece;
A method for forming a piezoelectric piece, comprising: Piezoelectric material made of a piezoelectric material having n-fold symmetry comprising a base, a plurality of detection arm portions extending radially around the base portion, and a plurality of excitation arm portions connected to the ends of the adjacent detection arm portions A piezoelectric piece forming method for forming a piece,
A plate-shaped body shaping step of slicing and shaping into a plate-like body by slicing at a predetermined angle or parallel to the main surface of the crystal grown by the crystal growth apparatus;
Internal corner arc shape formed by the inner corner portion become part of the arc shape formed by the base and the detector arm portion and the main surface of the plate-like body, and the detection arm section and the excitation arm portion A drilling step of drilling a part to be a part with a drill ;
A piezoelectric piece forming step of forming the piezoelectric piece on the plate-like body so that a portion of the plate-like body drilled by the drill becomes the arc-shaped corner of the piezoelectric piece;
A method for forming a piezoelectric piece, comprising: A piezoelectric piece forming method for forming a piezoelectric piece made of a piezoelectric material having n-fold symmetry, comprising a base, an excitation arm extending from one of the bases, and a detection arm extending from the other of the bases. ,
A crystal grown by a crystal growing apparatus is shaped and formed by a portion that becomes a corner portion formed by the base and the excitation arm on the main surface of the crystal, and the base and the detection arm. A drilling step for drilling a portion to be a corner to be entered,
A plate-shaped body shaping step of slicing the perforated crystal body in parallel with the main surface of the crystal body to form a plate-like body;
A piezoelectric piece forming step of forming the piezoelectric piece on the plate-like body so that the perforated portion of the plate-like body becomes the corner of the piezoelectric piece;
A method for forming a piezoelectric piece, comprising: A piezoelectric piece forming method for forming a piezoelectric piece made of a piezoelectric material having n-fold symmetry, comprising a base, an excitation arm extending from one of the bases, and a detection arm extending from the other of the bases. ,
A plate-shaped body shaping step of slicing and shaping into a plate-like body by slicing at a predetermined angle or parallel to the main surface of the crystal grown by the crystal growth apparatus;
And the inner corner portion become part of the arc shape formed between said base and the excitation arm portion in the main surface of the crystal, the internal corner portion of an arc shape formed between the base portion and the detection arm section A drilling step of drilling a part with a drill ;
A piezoelectric piece forming step of forming the piezoelectric piece on the plate-like body so that a portion of the plate-like body drilled by the drill becomes the arc-shaped corner of the piezoelectric piece;
A method for forming a piezoelectric piece, comprising:

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