JP7423231B2 - Manufacturing method of piezoelectric vibrating piece, piezoelectric vibrating piece and piezoelectric vibrator - Google Patents

Description

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

In a piezoelectric vibrating piece formed from an AT-cut crystal substrate, when the piezoelectric vibrating piece is made smaller and has a lower frequency, vibrations generated in an excitation section formed at the center become easier to propagate to the ends of the piezoelectric vibrating piece. Therefore, a structure that efficiently confines vibrational energy to the center is required. A so-called mesa-shaped piezoelectric vibrating piece is known in which the central part is thick and flat in order to confine the vibration energy of the main vibration due to thickness-shear vibration in the central part of the piezoelectric vibrating piece. For example, in the piezoelectric vibrating piece described in Patent Document 1, the mesa portion is formed by wet etching. At this time, since the piezoelectric vibrating piece formed by AT cutting has crystal anisotropy, the side surface of the mesa portion formed by wet etching becomes a natural crystal plane having a specific inclination angle.

Japanese Patent Application Publication No. 2008-067345

By the way, in the above-mentioned piezoelectric vibrating piece, among the side surfaces of the mesa portion which are natural crystal planes, especially the side formed by a crystal plane other than the m-plane (for example, the R-plane) is connected at an angle close to a right angle to the top surface. As a result, a sharp ridge line is formed at the connection between the top surface and the side surface of the mesa. As a result, the main vibration is reflected at the connection between the top surface and the side surface of the mesa portion, causing spurious oscillation and deteriorating the vibration characteristics.

Therefore, the present invention provides a method for manufacturing a piezoelectric vibrating piece that can manufacture a piezoelectric vibrating piece with excellent vibration characteristics, as well as a piezoelectric vibrating piece and a piezoelectric vibrator with excellent vibration characteristics.

The method for manufacturing a piezoelectric vibrating piece of the present invention is a method for manufacturing a piezoelectric vibrating piece having a piezoelectric plate formed of an AT-cut crystal substrate, wherein the piezoelectric plate has a first main body facing the + side in the Y'-axis direction. a second main surface facing the negative side in the Y'-axis direction; a first mesa portion provided on the first main surface and bulging toward the positive side in the Y'-axis direction; a second mesa portion that is provided and bulges toward the negative side in the Y'-axis direction, and each of the first mesa portion and the second mesa portion has a top surface perpendicular to the Y'-axis; a first mesa mask of the outer shape pattern of the first mesa portion is formed on the first surface of the wafer, and a first mesa mask of the outer shape pattern of the first mesa portion is formed on the second surface of the wafer; a mesa mask forming step of forming a second mesa mask of an external pattern of a mesa portion; a first etching step of wet etching the wafer through the first mesa mask and the second mesa mask; and the first mesa mask and the second mesa mask. a second etching step of wet-etching the wafer with the The etching amount of the wafer in the Y'-axis direction is h, and the amount of deviation of the center of the second mesa mask in the Z'-axis direction from the center of the first mesa mask in the Z'-axis direction to the - side in the Z'-axis direction. is D, the mesa mask forming step is characterized in that the first mesa mask and the second mesa mask are formed so as to satisfy the relationship d×1/3+2h<D<d×7/3+5h.

According to the present invention, in the mesa mask forming step, the first mesa mask and the second mesa mask are formed so as to satisfy the relationship d×1/3+2h<D<d×7/3+5h. As a result, the top surface of the first mesa portion overlaps with the second mesa portion in the Z'-axis direction, and the top surface of the second mesa portion overlaps with the first mesa portion in the Z'-axis direction. Therefore, vibration energy can be efficiently confined, and a piezoelectric vibrating piece with a low CI value can be manufactured. As described above, a piezoelectric vibrating piece with excellent vibration characteristics can be manufactured.

In the method for manufacturing a piezoelectric vibrating piece described above, a first outer shape mask of the outer shape pattern of the piezoelectric plate is formed on the first surface of the wafer, and a second outer shape mask of the outer shape pattern of the piezoelectric plate is formed on the second surface of the wafer. an outer shape mask forming step of forming an outer shape mask, and an outer shape etching step of wet etching the wafer through the first outer shape mask and the second outer shape mask, the outer shape mask forming step and the outer shape etching step. It may be performed after the second etching step.

According to the present invention, the outer shape of the piezoelectric plate is formed after other etching processes, so compared to a method in which the outer shape of the piezoelectric plate is formed before other etching processes, the piezoelectric plate can be shaped into a desired shape. Easy to form.

In the method for manufacturing a piezoelectric vibrating piece described above, a first outer shape mask of the outer shape pattern of the piezoelectric plate is formed on the first surface of the wafer, and a second outer shape mask of the outer shape pattern of the piezoelectric plate is formed on the second surface of the wafer. an outer shape mask forming step of forming an outer shape mask, and an outer shape etching step of wet etching the wafer through the first outer shape mask and the second outer shape mask, the outer shape mask forming step and the outer shape etching step. The etching step may be performed after the first etching step and before the second etching step.

According to the present invention, the end face of the outer periphery of the piezoelectric plate is formed by wet etching twice in two steps: the outer shape etching step and the second etching step. Therefore, compared to the case where the outer shape of the piezoelectric plate is formed after other etching steps, the angle of inclination of the plane appearing on the end face of the outer periphery of the piezoelectric plate with respect to the Z'-axis direction can be made smaller. Therefore, the piezoelectric vibrating piece manufactured by the manufacturing method of the present invention can efficiently attenuate vibrations transmitted to the ends of the piezoelectric plate at the end faces of the outer periphery. Therefore, a piezoelectric vibrating piece with excellent vibration characteristics can be manufactured.

In the method for manufacturing a piezoelectric vibrating piece described above, a first outer shape mask of the outer shape pattern of the piezoelectric plate is formed on the first surface of the wafer, and a second outer shape mask of the outer shape pattern of the piezoelectric plate is formed on the second surface of the wafer. an outer shape mask forming step of forming an outer shape mask; and an outer shape etching step of wet etching the wafer through the first outer shape mask and the second outer shape mask, the outer shape mask forming step and the outer shape etching step. It may be performed before the first etching step.

According to the present invention, the end face of the outer periphery of the piezoelectric plate is formed by wet etching three times in three steps: the outer shape etching step, the first etching step, and the second etching step. Therefore, compared to the case where the outer shape of the piezoelectric plate is formed after other etching steps, the angle of inclination of the plane appearing on the end face of the outer periphery of the piezoelectric plate with respect to the Z'-axis direction can be made smaller. Furthermore, compared to the case where the end face of the outer periphery of the piezoelectric plate is formed by wet etching twice, the angle of inclination of the plane appearing on the end face of the outer periphery of the piezoelectric plate with respect to the Z'-axis direction can be made smaller. Therefore, the piezoelectric vibrating piece manufactured by the manufacturing method of the present invention can more efficiently attenuate vibrations transmitted to the ends of the piezoelectric plate at the end faces of the outer periphery. Therefore, a piezoelectric vibrating piece with excellent vibration characteristics can be manufactured.

The piezoelectric vibrating piece of the present invention has a piezoelectric plate formed of an AT-cut crystal substrate, and the piezoelectric plate has a first main surface facing the + side in the Y'-axis direction and a first main surface facing the - side in the Y'-axis direction. a first mesa portion provided on the first main surface and bulging toward the + side in the Y'-axis direction; a bulging second mesa portion, each of the first mesa portion and the second mesa portion having a top surface perpendicular to the Y' axis, and a top surface surrounding the top surface and inclined with respect to the top surface. A side surface of the first mesa portion facing toward the + side in the Z′-axis direction is formed by three or more planes connected in the Y′-axis direction; Among the side surfaces, the side surface facing the − side in the Z'-axis direction is characterized in that three or more planes are formed in series in the Y'-axis direction.

According to the present invention, when three or more planes are each formed by natural crystal planes of quartz crystal, these natural crystal planes are inclined with respect to the Z'-axis direction, so that the Z of the entire side surface of the mesa portion is 'The inclination angle with respect to the axial direction is less than 90°. This makes it possible to smooth the change in the thickness of the piezoelectric vibrating piece in the mesa section, compared to a configuration in which the side surface of the mesa section is inclined at approximately 90 degrees with respect to the Z'-axis direction. Therefore, the CI value of the piezoelectric vibrating piece can be reduced.

In the piezoelectric vibrating piece described above, the inclination angle of the three or more planes of the first mesa section with respect to the Z'-axis direction becomes smaller toward the + side of the Y'-axis direction, and the three or more planes of the second mesa section The inclination angle of the three or more planes with respect to the Z'-axis direction may become smaller toward the negative side of the Y'-axis direction.

According to the present invention, the connection portion between the top surface and the side surface of each of the first mesa portion and the second mesa portion is leveled. As a result, reflection of vibration is reduced at the connection portion between the top surface and the side surface of each of the first mesa portion and the second mesa portion, and spurious oscillation is suppressed. Therefore, a piezoelectric vibrating piece with excellent vibration characteristics can be obtained.

In the piezoelectric vibrating piece described above, the inclination angle of the three or more planes of the first mesa section with respect to the Z'-axis direction increases toward the + side of the Y'-axis direction, and the three or more planes of the second mesa section The inclination angle of the three or more planes with respect to the Z'-axis direction may become larger toward the negative side of the Y'-axis direction.

According to the present invention, the thickness change of the piezoelectric vibrating piece becomes smaller toward the outer circumferential side of the piezoelectric plate on the side surfaces of each of the first mesa portion and the second mesa portion. Thereby, vibrations directed from each of the first mesa portion and the second mesa portion toward the outer circumferential portion of the piezoelectric plate can be efficiently damped. Therefore, the CI value of the piezoelectric vibrating piece can be reduced.

In the above piezoelectric vibrating piece, the side surface of the first mesa portion facing toward the + side in the Z′-axis direction has an inclination angle of less than 70° with respect to the Z′-axis direction, and the side surface of the second mesa portion The inclination angle of the side surface facing toward the Z'-axis direction with respect to the Z'-axis direction may be less than 70°.

According to the present invention, it is possible to make the thickness change of the piezoelectric vibrating piece smoother in the mesa portion, compared to a configuration in which the side surface of the mesa portion is inclined at approximately 90 degrees with respect to the Z'-axis direction. Therefore, the CI value of the piezoelectric vibrating piece can be reduced.

A piezoelectric vibrating piece of the present invention is characterized by comprising the piezoelectric vibrating piece described above and a package in which the piezoelectric vibrating piece is mounted.

According to the present invention, since the piezoelectric vibrating piece described above is provided, a piezoelectric vibrator having excellent vibration characteristics can be provided.

According to the present invention, it is possible to provide a method for manufacturing a piezoelectric vibrating piece that can manufacture a piezoelectric vibrating piece with excellent vibration characteristics, as well as a piezoelectric vibrating piece and a piezoelectric vibrator with excellent vibration characteristics.

FIG. 1 is an exploded perspective view of a piezoelectric vibrator according to a first embodiment. FIG. 2 is a plan view of the piezoelectric vibrating piece according to the first embodiment. FIG. 2 is a side view of the piezoelectric vibrating piece according to the first embodiment. FIG. 2 is a side view of the piezoelectric vibrating piece according to the first embodiment. 3 is a sectional view taken along line VV in FIG. 2. FIG. 1 is a flowchart showing a method for manufacturing a piezoelectric vibrating piece according to a first embodiment. FIG. 3 is a process diagram illustrating a method for manufacturing a piezoelectric vibrating piece according to a first embodiment. FIG. 3 is a process diagram illustrating a method for manufacturing a piezoelectric vibrating piece according to a first embodiment. FIG. 3 is a process diagram illustrating a method for manufacturing a piezoelectric vibrating piece according to a first embodiment. FIG. 3 is a process diagram illustrating a method for manufacturing a piezoelectric vibrating piece according to a first embodiment. FIG. 3 is a process diagram illustrating a method for manufacturing a piezoelectric vibrating piece according to a first embodiment. FIG. 3 is a process diagram illustrating a method for manufacturing a piezoelectric vibrating piece according to a first embodiment. 7 is a graph showing the relationship between the etching amount of the wafer and the inclination angle of the first side surface of the mesa portion. It is a side view which shows the modification of the piezoelectric vibrating piece based on 1st Embodiment. It is a side view which shows the modification of the piezoelectric vibrating piece based on 1st Embodiment. 3 is a diagram showing a piezoelectric vibrating piece according to a modification of the first embodiment, and is a cross-sectional view taken along the line VV in FIG. 2. FIG. It is a flow chart which shows the manufacturing method of the piezoelectric vibrating piece concerning a 2nd embodiment. FIG. 7 is a side view of a piezoelectric vibrating piece according to a second embodiment. FIG. 7 is a side view of a piezoelectric vibrating piece according to a modification of the second embodiment. It is a flowchart which shows the manufacturing method of the piezoelectric vibrating piece concerning a 3rd embodiment. FIG. 7 is a side view of a piezoelectric vibrating piece according to a third embodiment. FIG. 7 is a side view of a piezoelectric vibrating piece according to a modification of the third embodiment.

Embodiments of the present invention will be described below based on the drawings. In the following description, components having the same or similar functions are given the same reference numerals. Further, redundant explanations of these configurations may be omitted.

[First embodiment]
(piezoelectric vibrator)
First, a piezoelectric vibrator 1 according to a first embodiment will be described.
FIG. 1 is an exploded perspective view of a piezoelectric vibrator according to a first embodiment.
As shown in FIG. 1, the piezoelectric vibrator 1 includes a piezoelectric vibrating piece 10 and a package 70 in which the piezoelectric vibrating piece 10 is mounted. The piezoelectric vibrating piece 10 is a piezoelectric vibrating piece 10 that vibrates in a thickness shear mode. The piezoelectric vibrating piece 10 includes a piezoelectric plate 11 and an electrode film 12 that vibrates the piezoelectric plate 11 through its thickness.

The piezoelectric plate 11 is formed of an AT-cut crystal substrate. Here, AT cut refers to the X-axis relative to the Z-axis among the three crystal axes of artificial quartz: electrical axis (X-axis), mechanical axis (Y-axis), and optical axis (Z-axis). This is a processing method that cuts in a direction tilted by 35 degrees and 15 minutes (Z' axis direction). The piezoelectric vibrating piece 10 having the piezoelectric plate 11 cut out by AT cutting has the advantages of stable frequency-temperature characteristics, simple structure and shape, easy processing, and low CI value. In the following description, an XY'Z' coordinate system will be used when explaining the configuration of each figure. In this XY'Z' coordinate system, the Y' axis is an axis perpendicular to the X axis and the Z' axis. Furthermore, the X-axis direction, Y'-axis direction, and Z'-axis direction will be described with the direction of the arrow in the figure as the + direction, and the direction opposite to the arrow as the - direction. The piezoelectric plate 11 is formed into a rectangular plate shape with a thickness direction in the Y'-axis direction and a longitudinal direction in the X-axis direction.

FIG. 2 is a plan view of the piezoelectric vibrating piece according to the first embodiment. 3 and 4 are side views of the piezoelectric vibrating piece according to the first embodiment.
As shown in FIGS. 2 to 4, the piezoelectric plate 11 has a first main surface 15 facing the + side in the Y'-axis direction, a second main surface 16 facing the - side in the Y'-axis direction, and a first main surface 16 facing the negative side in the Y'-axis direction. An outer peripheral end surface 17 that connects the outer peripheral edges of the surface 15 and the second main surface 16 is provided. The piezoelectric plate 11 has mesa portions (a first mesa portion 20 and a second mesa portion 30) that bulge outward in the Y'-axis direction and serve as a vibration region on each of the first main surface 15 and the second main surface 16. It is said to be a so-called mesa type. Specifically, the first main surface 15 includes a first mesa portion 20 that bulges toward the + side in the Y'-axis direction at the center, and a first outer peripheral portion 21 that is located at the outer peripheral portion and surrounds the first mesa portion 20. and. The second main surface 16 includes a second mesa portion 30 that bulges toward the − side in the Y′-axis direction at the center, and a second outer peripheral portion 31 that is located at the outer peripheral portion and surrounds the second mesa portion 30. .

The first mesa portion 20 bulges out toward the + side in the Y′-axis direction with respect to the first outer peripheral portion 21 . The first mesa portion 20 is formed in the shape of a truncated quadrangular pyramid. The first mesa portion 20 includes a top surface 22 and four side surfaces 23, 24, 25, and 26 surrounding the top surface 22. The top surface 22 is formed into a rectangular shape whose longitudinal direction is in the X-axis direction when viewed from above. The top surface 22 is a flat surface perpendicular to the Y'-axis direction.

The four side surfaces 23, 24, 25, and 26 are each inclined with respect to the top surface 22. Each of the four side surfaces 23 , 24 , 25 , and 26 continues to the first outer circumferential portion 21 and connects the outer circumferential edge of the top surface 22 and the inner circumferential edge of the first outer circumferential portion 21 . The four side surfaces 23, 24, 25, and 26 are a first side surface 23 facing the + side in the Z'-axis direction, a second side surface 24 facing the negative side in the Z'-axis direction, and a third side surface facing the + side in the X-axis direction. 25, and a fourth side surface 26 facing toward the − side in the X-axis direction. The angle of inclination of the first side surface 23 with respect to the Z'-axis direction is 20° or more and less than 85°, more preferably 20° or more and less than 70°. Note that the inclination angle of the first side surface 23 with respect to the Z'-axis direction is defined by the angle θ1 that a virtual straight line L1 passing through both ends of the Y'Z' cross section of the first side surface 23 makes with the Z'-axis (Fig. 5). The virtual straight line L1 passes through the connection between the first side surface 23 and the first outer peripheral portion 21 and the connection between the first side surface 23 and the top surface 22. The same holds true for the inclination angles of the other side surfaces 24, 25, and 26 with respect to the Z'-axis direction.

Here, the specific shape of the first side surface 23 will be explained in detail.
FIG. 5 is a cross-sectional view taken along line VV in FIG. 2.
As shown in FIG. 5, the first side surface 23 is formed by a plurality of planes connected in the Y'-axis direction and having different inclination angles with respect to the Z'-axis direction. The plurality of planes are formed by natural crystal planes of the quartz crystal. In this embodiment, the plurality of planes includes three planes. Note that the plurality of planes may include four or more planes. Each of the plurality of planes has an inclination angle of 10° or more with respect to the Z'-axis direction. The first side surface 23 bulges in the direction away from the first mesa portion 20 (that is, the + side in the Z'-axis direction) with respect to the virtual straight line L1 in the Y'Z' cross section viewed from the X-axis direction. The inclination angles of the plurality of planes with respect to the Z'-axis direction become smaller toward the outside (+ side) in the Y'-axis direction. Note that if a plane with an inclination angle of less than 10 degrees with respect to the Z'-axis direction is formed between the first side surface 23 and the first outer circumferential part 21, the plane is included in the first outer circumferential part 21.

As shown in FIGS. 2 to 4, the first outer peripheral portion 21 is formed into a rectangular frame shape when viewed from above. The outer circumferential edge of the first outer circumferential portion 21 is connected to the edge of the outer circumferential end surface 17 on the + side in the Y'-axis direction.

As shown in FIGS. 3 and 4, the second mesa portion 30 bulges in the − side in the Y′-axis direction with respect to the second outer peripheral portion 31. As shown in FIGS. In this embodiment, the second mesa portion 30 is formed to be point symmetrical with the first mesa portion 20. The second mesa portion 30 is formed in the shape of a truncated quadrangular pyramid. The second mesa portion 30 includes a top surface 32 and four side surfaces 33, 34, 35, and 36 surrounding the top surface 32. The top surface 32 is formed into a rectangular shape whose longitudinal direction is in the X-axis direction when viewed from above. The top surface 32 is a flat surface perpendicular to the Y'-axis direction. The top surface 32 is formed to have the same shape and size as the top surface 22 of the first mesa portion 20 .

The four side surfaces 33, 34, 35, and 36 are each inclined with respect to the top surface 32. Each of the four side surfaces 33 , 34 , 35 , and 36 continues to the second outer peripheral portion 31 and connects the outer peripheral edge of the top surface 32 and the inner peripheral edge of the second outer peripheral portion 31 . The four side surfaces 33, 34, 35, and 36 are a first side surface 33 facing the negative side in the Z'-axis direction, a second side surface 34 facing the positive side in the Z'-axis direction, and a third side surface facing the negative side in the X-axis direction. 35, and a fourth side surface 36 facing toward the + side in the X-axis direction. The shape of each side surface 33 , 34 , 35 , 36 is similar to the shape of each side surface 23 , 24 , 25 , 26 of first mesa portion 20 .

The second outer peripheral portion 31 is formed into a rectangular frame shape in plan view. The outer circumferential edge of the second outer circumferential portion 31 is connected to the edge of the outer circumferential end surface 17 on the - side in the Y'-axis direction.

The outer peripheral end surface 17 is formed at an angle that follows the natural crystal plane of the quartz crystal. Of the outer peripheral end surface 17, a first end surface 41 facing the + side in the X-axis direction and a second end surface 42 facing the − side in the X-axis direction are each formed by a plurality of planes connected in the Y'-axis direction. As a result, at least at both end portions of the piezoelectric plate 11 in the X-axis direction, the thickness in the Y'-axis direction becomes gradually thinner toward the outside in the X-axis direction.

As shown in FIGS. 2 and 4, the electrode film 12 is formed on the outer surface of the piezoelectric plate 11. As shown in FIGS. The electrode film 12 includes excitation electrodes (first excitation electrode 61A and second excitation electrode 61B), mount electrodes (first mount electrode 62A and second mount electrode 62B), and wiring (first wiring 63A and second wiring 63B). ) and has. The electrode film 12 is formed of a single-layer film made of gold or the like, or a laminated film made of chromium or the like as a base layer and gold or the like as a top layer.

The first excitation electrode 61A is arranged on the top surface 22 of the first mesa portion 20. The first excitation electrode 61A is formed into a rectangular shape in a plan view, and is disposed inside the outer peripheral edge of the top surface 22 of the first mesa portion 20.
The second excitation electrode 61B is arranged on the top surface 32 of the second mesa portion 30. The second excitation electrode 61B is formed into a rectangular shape in plan view, and is arranged inside the outer peripheral edge of the top surface 32 of the second mesa portion 30.

The first mount electrode 62A is formed on the outer surface of a corner of the piezoelectric plate 11 located on the + side in the X-axis direction and the − side in the Z'-axis direction. The first mount electrode 62A is arranged over the first outer circumferential portion 21, the outer circumferential end surface 17, and the second outer circumferential portion 31. The first mount electrode 62A is formed into a rectangular shape whose longitudinal direction is the Z'-axis direction when viewed from the Y'-axis direction.

The second mount electrode 62B is formed on the outer surface of a corner of the piezoelectric plate 11 located on the + side in the X-axis direction and the + side in the Z'-axis direction. The second mount electrode 62B is arranged over the first outer circumferential portion 21, the outer circumferential end surface 17, and the second outer circumferential portion 31. The second mount electrode 62B is formed into a rectangular shape whose longitudinal direction is the Z'-axis direction when viewed from the Y'-axis direction.

The first wiring 63A connects the first excitation electrode 61A and the first mount electrode 62A on the first main surface 15.
The second wiring 63B connects the second excitation electrode 61B and the second mount electrode 62B on the second main surface 16.

As shown in FIG. 1, the package 70 houses the piezoelectric vibrating piece 10 inside the cavity C. The package 70 is formed by overlapping a base substrate 71 and a lid substrate 72. Both the base substrate 71 and the lid substrate 72 are made of ceramic material or the like.

The base substrate 71 includes a bottom wall portion 73 formed in a rectangular plate shape, and a side wall portion 74 erected from the peripheral edge of the bottom wall portion 73. A pair of internal electrodes 75 are formed on the inner surface of the bottom wall portion 73 . A pair of internal electrodes 75 are formed spaced apart in a predetermined direction. Furthermore, a pair of external electrodes (not shown) are formed on the outer surface of the bottom wall portion 73. The internal electrode 75 and the external electrode are connected by a through electrode (not shown) that penetrates the bottom wall portion 73.

The lid substrate 72 is formed into a rectangular plate shape. A peripheral portion of the lid substrate 72 is bonded to an end surface of the side wall portion 74 of the base substrate 71. A cavity C is formed in a region surrounded by the bottom wall 73 and side wall 74 of the base substrate 71 and the lid substrate 72.

The piezoelectric vibrating piece 10 is housed in the cavity C. The piezoelectric vibrating piece 10 is mounted on the bottom wall portion 73 of the base substrate 71 using a mounting member such as a conductive paste. Specifically, the first mount electrode 62A and the second mount electrode 62B of the piezoelectric vibrating piece 10 are mounted via a mounting member to a pair of internal electrodes 75 formed on the bottom wall portion 73 of the base substrate 71. Ru. As a result, the piezoelectric vibrating piece 10 is mechanically held by the package 70, and the first mount electrode 62A and the second mount electrode 62B are electrically connected to the internal electrode 75, respectively.

(Method for manufacturing piezoelectric vibrating piece)
Next, a method for manufacturing the piezoelectric vibrating piece 10 will be explained. In the following description, a method of forming a plurality of piezoelectric vibrating pieces 10 at once from an AT-cut crystal substrate (hereinafter referred to as wafer S) will be described.

FIG. 6 is a flowchart showing a method for manufacturing a piezoelectric vibrating piece according to the first embodiment. 7 to 12 are process diagrams illustrating the method for manufacturing the piezoelectric vibrating piece according to the first embodiment.
As shown in FIG. 6, the method for manufacturing the piezoelectric vibrating piece 10 of this embodiment mainly includes a wafer preparation step S10, a mesa mask forming step S20, a first mesa etching step S30 (first etching step), and a mesa mask removal step. Step S40, second mesa etching step S50 (second etching step), outer mask forming step S60, outer shape etching step S70, outer mask removing step S80, electrode film forming step S90, and singulation step S100 and.

First, a wafer preparation step S10 is performed. In the wafer preparation step S10, a wafer S made by AT-cutting a Lambertian crystal rough stone to a certain thickness is rough-processed by lapping, and then the process-affected layer is removed by etching. Thereafter, a mirror polishing process such as polishing is performed to prepare a wafer S having a predetermined thickness. In the following description, the first surface 80 of the wafer S is a main surface facing the + side in the Y'-axis direction, and corresponds to the first main surface 15 of the piezoelectric plate 11 described above. The second surface 81 of the wafer S is a main surface facing the negative side in the Y'-axis direction, and corresponds to the second main surface 16 of the piezoelectric plate 11.

Subsequently, a mesa mask forming step S20 is performed. As shown in FIG. 7, in the mesa mask forming step S20, a first mesa mask 82 having an external pattern of the first mesa portion 20 is formed on the first surface 80 of the wafer S, and a second mesa mask 82 is formed on the second surface 81 of the wafer S. A second mesa mask 83 having 30 external patterns is formed. The first mesa mask 82 and the second mesa mask 83 are formed by patterning a metal film using general photolithography. The metal film is, for example, a laminated film in which an etching protection film made of several tens of nanometers of chromium and an etching protection film made of several tens of nanometers of gold are sequentially laminated. In this embodiment, since the top surface 22 of the first mesa section 20 and the top surface 32 of the second mesa section 30 are the same in shape and the same size, the first mesa mask 82 and the second mesa mask 83 are also in the same shape and the same size. be.

Here, the relative positions of the first mesa mask 82 and the second mesa mask 83 will be explained.
The second mesa mask 83 is disposed offset from the first mesa mask 82 in the Z'-axis direction. Specifically, the center of the second mesa mask 83 in the Z'-axis direction is shifted from the center of the first mesa mask 82 in the Z'-axis direction by a distance D to the negative side in the Z'-axis direction.

Subsequently, a first mesa etching step S30 is performed. As shown in FIG. 8, in the first mesa etching step S30, the wafer S is wet-etched through the first mesa mask 82 and the second mesa mask 83. In the first mesa etching step S30, portions of both surfaces of the wafer S that are not masked by the first mesa mask 82 and the second mesa mask 83 are selectively etched. As a result, the portion of the wafer S that is not masked by the first mesa mask 82 and the second mesa mask 83 becomes thinner, and the portion that is masked by the first mesa mask 82 and the second mesa mask 83 becomes the first mesa portion 20 and the second mesa portion. The convex portion corresponds to 30. Hereinafter, the convex portion corresponding to the first mesa portion 20 will be referred to as a first mesa original shape portion 84, and the convex portion corresponding to the second mesa portion 30 will be referred to as a second mesa original shape portion 85.

The top surfaces 86 and 87 of each mesa original portion 84 and 85 are formed by the main surface of the wafer S, and are perpendicular to the Y' axis. The side surfaces of each of the original mesa portions 84 and 85 are formed by natural crystal faces of quartz crystal. A first side surface 88a facing toward the + side in the Z'-axis direction in the first mesa original portion 84 is an inclined surface that is more inclined with respect to the Z'-axis direction than a second side surface 88b facing toward the − side in the Z'-axis direction; It is formed by side etching proceeding below the first mesa mask 82. The same applies to the first side surface 89a of the second mesa original shape portion 85 facing the − side in the Z′-axis direction. On the other hand, the second side surface 88b of the first mesa original shape portion 84 includes an m-plane, and side etching has not progressed. The same applies to the second side surface 89b of the second mesa original portion 85 facing the + side in the Z'-axis direction. Therefore, a sharper ridgeline is formed at the connection between the top surface 86 of the first mesa original shape section 84 and the first side surface 88a than at the connection section between the top surface 86 of the first mesa original shape section 84 and the second side surface 88b. There is. Further, a sharper ridge line is formed at the connection between the top surface 87 of the second mesa original shape section 85 and the first side surface 89a than at the connection section between the top surface 87 of the second mesa original shape section 85 and the second side surface 89b. There is.

Here, the side etching amount of the first side surface 88a in the first mesa original shape portion 84 is d×1/3, where d is the etching amount of the wafer S in the Y'-axis direction in the first mesa etching step S30. ing. The same applies to the amount of side etching on the first side surface 89a of the second mesa original shape portion 85. Therefore, the dimension of the top surface 86 of the first mesa original portion 84 in the Z'-axis direction is smaller than the dimension of the first mesa mask 82 in the Z'-axis direction by d×1/3. Further, the center of the top surface 86 of the first mesa original shape portion 84 in the Z'-axis direction is shifted by d/6 from the center of the first mesa mask 82 in the Z'-axis direction to the - side in the Z'-axis direction. . Further, the dimension of the top surface 87 of the second mesa original shape portion 85 in the Z'-axis direction is smaller than the dimension of the second mesa mask 83 in the Z'-axis direction by d×1/3. Further, the center of the top surface 87 of the second mesa original portion 85 in the Z'-axis direction is shifted by d×1/6 on the + side of the Z'-axis with respect to the center of the second mesa mask 83 in the Z'-axis direction. ing. As a result, the center of the top surface 87 of the second mesa original portion 85 in the Z′ axis direction is located on the negative side of the Z′ axis direction with respect to the center of the top surface 86 of the first mesa original portion 84 in the Z′ axis direction. It is located at the position of D-d×1/3.

Subsequently, a mesa mask removal step S40 is performed. As shown in FIG. 9, in the mesa mask removal step S40, the first mesa mask 82 and the second mesa mask 83 are removed.

Subsequently, a second mesa etching step S50 is performed. As shown in FIG. 10, in the second mesa etching step S50, the wafer S is wet etched. The first mesa portion 20 is formed by etching the first mesa original portion 84. The second mesa portion 30 is formed by etching the second mesa original portion 85 .

In the wet etching of the second mesa etching step S50, the vertical surface of the wafer S in the Y'-axis direction is approximately evenly etched in the normal direction. In other words, the top surfaces 86 and 87 of the first mesa original part 84 and the second mesa original part 85, as well as the peripheries of the first mesa original part 84 and the second mesa original part 85, are etched inward in the Y'-axis direction. Ru. The top surfaces 86 and 87 of the first mesa original portion 84 and the second mesa original portion 85 are etched, thereby forming the top surfaces 22 and 32 of the first mesa portion 20 and the second mesa portion 30, respectively. The height of each of the first mesa portion 20 and the second mesa portion 30 in the Y'-axis direction becomes the etching amount d of the wafer S in the Y'-axis direction in the first mesa etching step S30 (see FIG. 8).

Furthermore, in the wet etching of the second mesa etching step S50, the first side surface 88a of the first mesa original shape section 84 and the first side surface 89a of the second mesa original shape section 85 are etched in the normal direction thereof. By etching the first side surfaces 88a and 89a of the first mesa original portion 84 and the second mesa original portion 85, the first side surfaces 23 and 33 of the first mesa portion 20 and the second mesa portion 30, respectively, are formed. Ru. By etching the connecting portion between the top surface 86 of the first mesa original portion 84 and the first side surface 88a, the first side surface 88a of the first mesa original portion 84 has a small inclination angle with respect to the Z'-axis direction. The same applies to the first side surface 89a of the second mesa original shape portion 85.

FIG. 13 is a graph showing the relationship between the etching amount of the wafer and the inclination angle of the first side surface of the mesa portion. In FIG. 13, the horizontal axis is the etching amount h of the wafer S in the Y'-axis direction in the second mesa etching step S50 (see FIG. 10). The vertical axis is the inclination angle of the first side surface 23 of the first mesa portion 20 with respect to the Z'-axis direction.
As shown in FIG. 13, as the amount of etching of the wafer S in the Y'-axis direction in the second mesa etching step S50 increases, the inclination angle of the first side surface 23 of the first mesa portion 20 becomes smaller. In this embodiment, by setting the etching amount of the wafer S in the Y'-axis direction in the second mesa etching step S50 to 8 μm or less, the inclination angle of the first side surface 23 of the first mesa portion 20 with respect to the Z'-axis direction is 20 μm or less. ° or more.

As shown in FIG. 10, when the etching amount of the wafer in the Y'-axis direction in the second mesa etching step S50 is h, the connection between the top surface 86 of the first mesa original shape part 84 and the first side surface 88a is as follows. Due to the wet etching in the second mesa etching step S50, it is shifted to the - side in the Z'-axis direction. The connection portion between the top surface 87 of the second mesa original shape portion 85 and the first side surface 89a is shifted toward the + side in the Z'-axis direction by wet etching in the second mesa etching step S50. Note that the end of the first side surface 88a of the first mesa original portion 84 on the + side in the Z'-axis direction is shifted by 1.2 h to the - side in the Z'-axis direction by wet etching in the second mesa etching step S50. The same applies to the first side surface 89a of the second mesa original shape portion 85.

Further, in the wet etching of the second mesa etching step S50, the second side surface 88b of the first mesa original shape part 84 and the second side surface 89b of the second mesa original shape part 85 are not etched in the normal direction thereof. Therefore, the second side surfaces 88b and 89b of the first mesa original portion 84 and the second mesa original portion 85 become the second side surfaces 24 and 34 of the first mesa portion 20 and the second mesa portion 30, respectively. The connection portion between the top surface 86 of the first mesa original shape portion 84 and the second side surface 88b is shifted toward the − side in the Z′-axis direction by wet etching in the second mesa etching step S50. The connection portion between the top surface 87 of the second mesa original shape portion 85 and the second side surface 89b is shifted toward the + side in the Z'-axis direction by wet etching in the second mesa etching step S50.

The center of the top surface 86 of the first mesa original portion 84 in the Z'-axis direction is shifted by 2.5 h toward the - side in the Z'-axis direction by the wet etching in the second mesa etching step S50. Further, the center of the top surface 87 of the second mesa original shape portion 85 in the Z'-axis direction is shifted by 2.5 h toward the + side in the Z'-axis direction by the wet etching in the second mesa etching step S50. As a result, the center of the top surface 32 of the second mesa section 30 in the Z'-axis direction is shifted D toward the - side of the Z'-axis with respect to the center of the top surface 22 of the first mesa section 20 in the Z'-axis direction. It is located at -d x 1/3-5h.

Subsequently, an external mask forming step S60 is performed. As shown in FIG. 11, in the contour mask forming step S60, a first contour mask 90 of the contour pattern of the piezoelectric plate 11 is formed on the first surface 80 of the wafer S, and a first contour mask 90 of the contour pattern of the piezoelectric plate 11 is formed on the second surface 81 of the wafer S. A second external mask 91 having an external pattern is formed. The first external mask 90 and the second external mask 91 are formed by patterning a metal film using general photolithography. The metal film is similar to the first mesa mask 82 and the second mesa mask 83. The first outer mask 90 and the second outer mask 91 completely cover the first mesa portion 20 and the second mesa portion 30.

Subsequently, an outer shape etching step S70 is performed. As shown in FIG. 12, in the contour etching step S70, the wafer S is wet-etched through the first contour mask 90 and the second contour mask 91. As a result, the portions of the wafer S that are not masked by the first external mask 90 and the second external mask 91 are selectively etched, and the external shape of the piezoelectric plate 11 is formed. At this time, the wafer S is etched to follow the natural crystal plane, and the outer peripheral end surface 17 of the piezoelectric plate 11 is formed.

Subsequently, a contour mask removal step S80 is performed. In the external mask removal step S80, the first external mask 90 and the second external mask 91 are removed.

Subsequently, an electrode film 12 is formed on the wafer S in an electrode film forming step S90, and then the wafer S is diced into pieces for each piezoelectric plate 11 in a singulation step S100.
Through the above steps, a plurality of piezoelectric vibrating pieces 10 can be manufactured from the wafer S at once.

In the mesa mask forming step S20 described above, by setting the deviation amount D of the second mesa mask 83 with respect to the first mesa mask 82 to be d×1/3+5h, the center of the top surface 32 of the second mesa portion 30 in the Z′ axis direction is They are provided at the same position in the Z'-axis direction with respect to the center of the top surface 22 of the first mesa portion 20 in the Z'-axis direction. That is, the top surfaces 22 and 32 of the first mesa section 20 and the second mesa section 30 completely overlap each other in the Z'-axis direction when viewed from the Y'-axis direction.

Note that in the mesa mask forming step S20, the amount of deviation D of the second mesa mask 83 with respect to the first mesa mask 82 may be smaller than d×1/3+5h. In this case, the amount of deviation D of the second mesa mask 83 with respect to the first mesa mask 82 is made larger than d×1/3+2h. That is, in the mesa mask forming step S20, the first mesa mask 82 and the second mesa mask 83 are formed so as to satisfy the relationship d×1/3+2h<D≦d×1/3+5h. As a result, as shown in FIG. 14, the top surface 22 of the first mesa section 20 overlaps the second mesa section 30 in the Z'-axis direction, and the top surface 32 of the second mesa section 30 overlaps the first mesa section 20 in the Z' direction. 'Overlap in the axial direction.

Further, in the mesa mask forming step S20, the amount of deviation D of the second mesa mask 83 with respect to the first mesa mask 82 may be larger than d×1/3+5h. In this case, the amount of deviation D of the second mesa mask 83 with respect to the first mesa mask 82 is made smaller than d×7/3+5h. That is, in the mesa mask forming step S20, the first mesa mask 82 and the second mesa mask 83 are formed so as to satisfy the relationship d×1/3+5h≦D<d×7/3+5h. As a result, as shown in FIG. 15, the top surface 22 of the first mesa section 20 overlaps the second mesa section 30 in the Z'-axis direction, and the top surface 32 of the second mesa section 30 overlaps the first mesa section 20 in the Z' direction. 'Overlap in the axial direction.

As described above, the method for manufacturing the piezoelectric vibrating piece 10 of the present embodiment includes forming the first mesa mask 82 having the outer shape pattern of the first mesa portion 20 on the first surface 80 of the wafer S, and A mesa mask forming step S20 in which a second mesa mask 83 having an external pattern of the second mesa portion 30 is formed on the surface 81, and a first mesa etching step S30 in which the wafer S is wet-etched through the first mesa mask 82 and the second mesa mask 83. , a second mesa etching step S50 in which the wafer S is wet-etched with the first mesa mask 82 and the second mesa mask 83 removed.
According to this method, in the first mesa etching step S30, a convex portion (first mesa original shape portion 84) corresponding to the first mesa portion 20 is formed in a portion of the wafer S that is masked by the first mesa mask 82; A convex portion (second mesa original shape portion 85) corresponding to the second mesa portion 30 is formed in a portion masked by the two-mesa mask 83. In the second mesa etching step S50, the ridgeline of the convex portion is etched, so that the connection portions between the top surfaces 22, 32 and the first side surfaces 23, 33 in the first mesa portion 20 and the second mesa portion 30, respectively, are leveled. Ru. Therefore, the piezoelectric vibrating piece 10 manufactured by the manufacturing method of the present embodiment vibrates at the connection portion between the top surfaces 22, 32 and the first side surfaces 23, 33 in the first mesa portion 20 and the second mesa portion 30, respectively. reflection is reduced, and spurious oscillations are suppressed.
Moreover, in the mesa mask forming step S20, the first mesa mask 82 and the second mesa mask 83 are formed so as to satisfy the relationship d×1/3+2h<D<d×7/3+5h. As a result, the top surface 22 of the first mesa section 20 overlaps the second mesa section 30 in the Z'-axis direction, and the top surface 32 of the second mesa section 30 overlaps the first mesa section 20 in the Z'-axis direction. Therefore, it is possible to efficiently confine vibration energy and manufacture a piezoelectric vibrating piece 10 with a low CI value.
As described above, it is possible to manufacture the piezoelectric vibrating piece 10 with excellent vibration characteristics.

In addition, since the connecting portions between the top surfaces 22 and 32 and the first side surfaces 23 and 33 in the first mesa portion 20 and the second mesa portion 30 are leveled, the chipping in the first mesa portion 20 and the second mesa portion 30 is smoothed. It is possible to suppress the occurrence of cracks, cracks, etc.

Furthermore, the method for manufacturing the piezoelectric vibrating piece 10 of the present embodiment includes an outer mask forming step S60 in which a first outer mask 90 and a second outer mask 91 of the outer pattern of the piezoelectric plate 11 are formed; The method further includes an outer shape etching step S70 in which the wafer S is wet-etched through the second outer shape mask 91, and the outer shape mask forming step S60 and the outer shape etching step S70 are performed after the second mesa etching step S50.
According to this method, the outer shape of the piezoelectric plate 11 is formed after other etching steps, so compared to a method in which the outer shape of the piezoelectric plate 11 is formed before other etching steps, the piezoelectric plate 11 can be formed into a desired shape. Easy to form into shapes.

Furthermore, in the piezoelectric vibrating piece 10 and the piezoelectric vibrator 1 of the present embodiment, the first side surface 23 of the first mesa portion 20 facing the + side in the Z'-axis direction is formed by three planes connected in the Y'-axis direction. , the first side surface 33 of the second mesa portion 30 facing the − side in the Z'-axis direction is formed by three planes connected in the Y'-axis direction.
According to this configuration, since the natural crystal planes of the quartz crystal forming each of the three planes of the first side surfaces 23 and 33 are inclined with respect to the Z'-axis direction, the first The inclination angle of the entire side surface 23 with respect to the Z'-axis direction and the inclination angle of the entire first side surface 33 of the second mesa portion 30 with respect to the Z'-axis direction are each less than 90°. This smoothes the thickness change of the piezoelectric vibrating piece 10 in the first mesa part 20 and the second mesa part 30, compared to a configuration in which the side surface of the mesa part is inclined at approximately 90 degrees with respect to the Z'-axis direction. becomes possible. Therefore, the CI value of the piezoelectric vibrating piece 10 can be reduced.

Furthermore, the inclination angle of the three planes of the first side surface 23 of the first mesa section 20 with respect to the Z'-axis direction becomes smaller as it goes toward the + side of the Y'-axis direction, and The inclination angles of the three planes with respect to the Z'-axis direction become smaller toward the negative side of the Y'-axis direction.
According to this configuration, the connection portion between the top surface 22 and the first side surface 23 in the first mesa portion 20 and the connection portion between the top surface 32 and the first side surface 33 in the second mesa portion 30 are made even. As a result, reflection of vibration is reduced at the connection portions of each of the first mesa portion 20 and the second mesa portion 30, and spurious oscillations are suppressed. Therefore, a piezoelectric vibrating piece 10 with excellent vibration characteristics can be obtained.

The angle of inclination of the first side surface 23 of the first mesa section 20 with respect to the Z'-axis direction is preferably less than 70 degrees, and the angle of inclination of the first side surface 33 of the second mesa section 30 with respect to the Z'-axis direction is preferably less than 70 degrees. It is preferred that the angle is less than 70°.
According to this configuration, the thickness change of the piezoelectric vibrating piece 10 in the first mesa portion 20 and the second mesa portion 30 can be suppressed compared to a configuration in which the side surface of the mesa portion is inclined at approximately 90° with respect to the Z'-axis direction. It is possible to make it smooth. Therefore, the CI value of the piezoelectric vibrating piece 10 can be reduced.

[Modification of the first embodiment]
In the first embodiment, the first side surface 23 of the first mesa section 20 and the first side surface 33 of the second mesa section 30 are aligned with the virtual straight line L1 in the Y'Z' cross section viewed from the X-axis direction. In contrast, it bulges out in a direction away from the mesa portion, but is not limited thereto.

FIG. 16 is a diagram showing a piezoelectric vibrating piece according to a modification of the first embodiment, and is a sectional view taken along the line VV in FIG. 2.
As shown in FIG. 16, the first side surface 23 of the first mesa portion 20 is formed by a plurality of planes connected in the Y'-axis direction and having different inclination angles with respect to the Z'-axis direction. The plurality of planes are formed by natural crystal planes of the quartz crystal. In this modification, the plurality of planes includes three planes. Note that the plurality of planes may include four or more planes. Each of the plurality of planes has an inclination angle of 10° or more with respect to the Z'-axis direction. The first side surface 23 is recessed in a direction approaching the center of the first mesa portion 20 (i.e., on the - side in the Z'-axis direction) with respect to the virtual straight line L1 in the Y'Z' cross section viewed from the X-axis direction. . The inclination angles of the plurality of planes with respect to the Z'-axis direction become larger toward the outside (+ side) in the Y'-axis direction. Even in this case, the angle of inclination of the first side surface 23 with respect to the Z'-axis direction is 20° or more and less than 85°, more preferably 20° or more and less than 70°. Although not shown, the second mesa portion 30 is formed to be point symmetrical with the first mesa portion, and the shape of the first side surface 33 of the second mesa portion 30 is the same as that of the first side surface 23 of the first mesa portion. The shape will be similar.

The shape of the first side surface 23 of the first mesa portion 20 in this modification is obtained by shortening the wet etching time in the second mesa etching step S50 of the method for manufacturing the piezoelectric vibrating reed 10 of the first embodiment. That is, by appropriately adjusting the wet etching time in the second mesa etching step S50, the first side surface 23 having the shape shown in FIG. 5 or the first side surface 23 having the shape shown in FIG. 16 can be formed.

As described above, according to the piezoelectric vibrating piece 10 of this modification, the angle of inclination of the first side surface 23 of the first mesa portion 20 with respect to the Z'-axis direction is preferably less than 70°, so that the first embodiment Similarly, it is possible to smooth the thickness change of the piezoelectric vibrating piece 10 in the first mesa portion 20. The same applies to the second mesa portion 30. Therefore, the CI value of the piezoelectric vibrating piece 10 can be reduced.

In addition, in this modification, the inclination angle of the three planes of the first side surface 23 of the first mesa section 20 with respect to the Z'-axis direction increases toward the + side of the Y'-axis direction, and The three planes of the first side surface 33 have an inclination angle with respect to the Z'-axis direction that increases toward the - side in the Y'-axis direction.
According to this configuration, the change in the thickness of the piezoelectric vibrating piece 10 becomes smaller toward the outer circumferential side of the piezoelectric plate 11 on the first side surface 23 of the first mesa section 20 and the first side surface 33 of the second mesa section 30, respectively. Thereby, vibrations directed from each of the first mesa portion 20 and the second mesa portion 30 toward the outer peripheral portion of the piezoelectric plate 11 can be efficiently damped. Therefore, the CI value of the piezoelectric vibrating piece 10 can be reduced.

[Second embodiment]
(Method for manufacturing piezoelectric vibrating piece)
Next, a method for manufacturing the piezoelectric vibrating piece 10 of the second embodiment will be described.
FIG. 17 is a flowchart showing a method for manufacturing a piezoelectric vibrating piece according to the second embodiment. FIG. 17 is a side view of the piezoelectric vibrating piece according to the second embodiment.
As shown in FIG. 17, in the method of manufacturing the piezoelectric vibrating piece 10 of the second embodiment, the outer shape mask forming step S60, the outer shape etching step S70, and the outer shape mask removing step S80 are performed after the first mesa etching step S30 and after the second mesa etching step S30. This differs from the first embodiment in that it is performed before the mesa etching step S50. Note that the configuration other than that described below is the same as that of the first embodiment.

In the method for manufacturing the piezoelectric vibrating piece 10 of this embodiment, following the mesa mask removal step S40, an outer mask forming step S60, an outer shape etching step S70, and an outer mask removing step S80 are performed in this order. The outer shape mask forming step S60, the outer shape etching step S70, and the outer shape mask removing step S80 are respectively similar to those in the first embodiment.

Subsequently, a second mesa etching step S50 is performed. The second mesa etching step S50 of the second embodiment differs from the first embodiment in that a portion corresponding to the outer peripheral end surface 17 of the piezoelectric plate 11 is etched. That is, the outer peripheral end surface 17 of the piezoelectric plate 11 is wet-etched twice in two steps: the outer shape etching step S70 and the second mesa etching step S50. As a result, as shown in FIG. 18, the first mesa portion 20 is formed on the third end surface 43 facing the + side in the Z'-axis direction and the fourth end surface 44 facing the negative side in the Z'-axis direction of the outer peripheral end surface 17. A plurality of planes inclined with respect to the Z'-axis direction are generated by the same phenomenon as in the formation of the first side surfaces 23 and 33 of the second mesa portion 30. As a result, the end portions of the piezoelectric plate 11 on both sides in the Z'-axis direction gradually become thinner in the Y'-axis direction toward the outside in the Z'-axis direction. Note that in the example shown in FIG. 18, the third end surface 43 and the fourth end surface 44 each include a plurality of planes that are inclined in the same direction with respect to the Z'-axis direction, but as shown in FIG. It may also include a plurality of planes that are inclined to different sides with respect to each other. The inclinations of the plurality of planes provided on each of the third end surface 43 and the fourth end surface 44 may be adjusted as appropriate by the positional relationship in the Z'-axis direction of the first external mask 90 and the second external mask 91 (both see FIG. 11). Can be done.

Subsequently, an electrode film forming step S90 and a singulation step S100 are performed in this order. The electrode film forming step S90 and the singulation step S100 are the same as in the first embodiment.

In this embodiment, the mesa mask removing step S40 is followed by the outer mask forming step S60, but the mesa mask removing step S40 may be omitted and the outer mask forming step S60 may be performed. That is, the external masks 90 and 91 may be formed so as to overlap the mesa masks 82 and 83.

As explained above, the method for manufacturing the piezoelectric vibrating piece 10 of the present embodiment includes the mesa mask forming step S20, the first mesa etching step S30, and the second mesa etching step S50, so it has the same effect as the first embodiment. It can be effective.

Further, in this embodiment, the outer mask forming step 0 and the outer shape etching step S70 are performed after the first mesa etching step S30 and before the second mesa etching step S50.
According to this method, the outer peripheral end surface 17 of the piezoelectric plate 11 is formed by wet etching twice in two steps: the outer shape etching step S70 and the second mesa etching step S50. Therefore, compared to the case where the outer shape of the piezoelectric plate 11 is formed after other etching steps, the angle of inclination of the plane appearing on the outer peripheral end surface 17 of the piezoelectric plate 11 with respect to the Z'-axis direction can be made smaller. Therefore, the piezoelectric vibrating piece 10 manufactured by the manufacturing method of this embodiment can efficiently attenuate vibrations transmitted to the ends of the piezoelectric plate 11 at the outer peripheral end surface 17. Therefore, a piezoelectric vibrating piece 10 with excellent vibration characteristics can be manufactured.

[Third embodiment]
(Method for manufacturing piezoelectric vibrating piece)
Next, a method for manufacturing a piezoelectric vibrating piece according to a third embodiment will be described.
FIG. 20 is a flowchart showing a method for manufacturing a piezoelectric vibrating piece according to the third embodiment. FIG. 19 is a side view of the piezoelectric vibrating piece according to the third embodiment.
As shown in FIG. 20, the method for manufacturing the piezoelectric vibrating piece 10 of the third embodiment is that the outer mask forming step S60, the outer etching step S70, and the outer mask removing step S80 are performed before the first mesa etching step S30. , which is different from the first embodiment. Note that the configuration other than that described below is the same as that of the first embodiment.

In the method for manufacturing the piezoelectric vibrating piece 10 of this embodiment, following the wafer preparation step S10, a contour mask forming step S60, a contour etching step S70, and a contour mask removal step S80 are performed in this order. The outer shape mask forming step S60, the outer shape etching step S70, and the outer shape mask removing step S80 are respectively similar to those in the first embodiment.

Subsequently, a mesa mask forming step S20 and a first mesa etching step S30 are performed in this order. The mesa mask forming step S20 is similar to the first embodiment. The first mesa etching step S30 of the third embodiment differs from the first embodiment in that a portion corresponding to the outer peripheral end surface 17 of the piezoelectric plate 11 is etched.

Subsequently, a mesa mask removal step S40 and a second mesa etching step S50 are performed in this order. The mesa mask removal step S40 is similar to the first embodiment. The second mesa etching step S50 of the third embodiment differs from the first embodiment in that a portion corresponding to the outer peripheral end surface 17 of the piezoelectric plate 11 is etched. That is, the outer peripheral end surface 17 of the piezoelectric plate 11 is wet-etched three times in three steps: the outer shape etching step S70, the first mesa etching step S30, and the second mesa etching step S50. As a result, as shown in FIG. 21, the first mesa portion 20 is formed on the third end surface 43 facing the + side in the Z'-axis direction and the fourth end surface 44 facing the negative side in the Z'-axis direction of the outer peripheral end surface 17. A plurality of planes inclined with respect to the Z'-axis direction are generated by the same phenomenon as in the formation of the first side surfaces 23 and 33 of the second mesa portion 30. As a result, the end portions of the piezoelectric plate 11 on both sides in the Z'-axis direction gradually become thinner in the Y'-axis direction toward the outside in the Z'-axis direction. Note that in the example shown in FIG. 21, the third end surface 43 and the fourth end surface 44 each include a plurality of planes that are inclined in the same direction with respect to the Z'-axis direction, but as shown in FIG. It may also include a plurality of planes that are inclined to different sides with respect to each other. The inclinations of the plurality of planes provided on each of the third end surface 43 and the fourth end surface 44 may be adjusted as appropriate by the positional relationship in the Z'-axis direction of the first external mask 90 and the second external mask 91 (both see FIG. 11). Can be done.

Subsequently, an electrode film forming step S90 and a singulation step S100 are performed in this order. The electrode film forming step S90 and the singulation step S100 are the same as in the first embodiment.

As explained above, the method for manufacturing the piezoelectric vibrating piece 10 of the present embodiment includes the mesa mask forming step S20, the first mesa etching step S30, and the second mesa etching step S50, so it has the same effect as the first embodiment. It can be effective.

Further, in this embodiment, the outer mask forming step S60 and the outer shape etching step S70 are performed before the first mesa etching step S30.
According to this method, the outer peripheral end surface 17 of the piezoelectric plate 11 is formed by wet etching three times in three steps: an outer shape etching step S70, a first mesa etching step S30, and a second mesa etching step S50. Therefore, compared to the case where the outer shape of the piezoelectric plate 11 is formed after other etching steps, the angle of inclination of the plane appearing on the outer peripheral end surface 17 of the piezoelectric plate 11 with respect to the Z'-axis direction can be made smaller. Furthermore, compared to the case where the outer circumferential end surface 17 of the piezoelectric plate 11 is formed by wet etching twice as in the second embodiment, the inclination angle of the plane appearing on the outer circumferential end surface 17 of the piezoelectric plate 11 with respect to the Z'-axis direction is Can be made smaller. Therefore, the piezoelectric vibrating piece 10 manufactured by the manufacturing method of the present embodiment can more efficiently attenuate vibrations transmitted to the ends of the piezoelectric plate 11 at the outer peripheral end surface 17. Therefore, a piezoelectric vibrating piece 10 with excellent vibration characteristics can be manufactured.

Note that the present invention is not limited to the above-described embodiments described with reference to the drawings, and various modifications can be made within the technical scope thereof.
For example, in the above embodiment, the piezoelectric vibrating piece has been described with a structure in which one mesa portion is formed on each of the first main surface 15 and the second main surface 16 of the piezoelectric plate 11, but the present invention is not limited to this. For example, the mesa portion may be formed in multiple stages.

Further, in the above-described embodiment, the piezoelectric plate 11 is formed in a rectangular plate shape whose longitudinal direction is in the X-axis direction, but the piezoelectric plate 11 is not limited to this, and may be formed in a rectangular plate shape whose longitudinal direction is in the Z'-axis direction. may have been done.

Further, in the above embodiment, all of the mesa masks 82 and 83 are removed in the mesa mask removal step S40, but the present invention is not limited to this. In the second mesa etching step S50, it is only necessary to etch the connecting portion between the top surface and the side surface of the mesa portion, that is, only a portion of the mesa mask may be removed. This makes it possible to form a multi-stage mesa, and also to level the connection between the top surface and the side surface of the mesa portion.

In addition, it is possible to appropriately replace the components in the above-described embodiments with well-known components without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1... Piezoelectric vibrator 10... Piezoelectric vibrating piece 11... Piezoelectric plate 15... First main surface 16... Second main surface 20... First mesa part 22... Top surface 23... First side surface (side surface) 24... Second side surface ( 25... Third side surface (side surface) 26... Fourth side surface (side surface) 30... Second mesa portion 32... Top surface 33... First side surface (side surface) 34... Second side surface (side surface) 35... Third side surface ( 36... Fourth side (side) 70... Package 80... First surface 81... Second surface 82... First mesa mask 83... Second mesa mask 90... First outer shape mask 91... Second outer shape mask S... Wafer S20... Mesa mask formation process S30...First mesa etching process (first etching process) S50...Second mesa etching process (second etching process) S60...Outline mask formation process S70...Outline etching process

Claims (4)

A method for manufacturing a piezoelectric vibrating piece having a piezoelectric plate formed of an AT-cut crystal substrate, the method comprising:
The piezoelectric plate is
a first main surface facing the + side in the Y'-axis direction;
a second main surface facing the − side in the Y′-axis direction;
a first mesa portion provided on the first main surface and bulging toward the + side in the Y′-axis direction;
a second mesa portion provided on the second main surface and bulging toward the − side in the Y′-axis direction;
Equipped with
Each of the first mesa portion and the second mesa portion is
a top surface perpendicular to the Y'axis;
a side surface surrounding the top surface and inclined with respect to the top surface;
Equipped with
a mesa mask forming step of forming a first mesa mask having an external pattern of the first mesa portion on a first surface of the wafer, and forming a second mesa mask having an external pattern of the second mesa portion on a second surface of the wafer;
a first etching step of wet etching the wafer through the first mesa mask and the second mesa mask;
a second etching step of wet etching the wafer with the first mesa mask and the second mesa mask removed;
Equipped with
The height of the first mesa part and the second mesa part in the Y' axis direction is d,
Let h be the etching amount of the wafer in the Y'-axis direction in the second etching step,
When the amount of deviation of the center of the second mesa mask in the Z'-axis direction from the center of the first mesa mask in the Z'-axis direction to the − side in the Z'-axis direction is D,
In the mesa mask forming step,
d×1/3+2h<D<d×7/3+5h
forming the first mesa mask and the second mesa mask so as to satisfy the following relationship;
A method for manufacturing a piezoelectric vibrating piece, characterized by: forming a first external mask of the external pattern of the piezoelectric plate on the first surface of the wafer, and forming a second external mask of the external pattern of the piezoelectric plate on the second surface of the wafer; ,
a contour etching step of wet etching the wafer through the first contour mask and the second contour mask;
Equipped with
performing the outer shape mask forming step and the outer shape etching step after the second etching step;
The method for manufacturing a piezoelectric vibrating piece according to claim 1. forming a first external mask of the external pattern of the piezoelectric plate on the first surface of the wafer, and forming a second external mask of the external pattern of the piezoelectric plate on the second surface of the wafer; ,
a contour etching step of wet etching the wafer through the first contour mask and the second contour mask;
Equipped with
performing the outer shape mask forming step and the outer shape etching step after the first etching step and before the second etching step;
The method for manufacturing a piezoelectric vibrating piece according to claim 1. forming a first external mask of the external pattern of the piezoelectric plate on the first surface of the wafer, and forming a second external mask of the external pattern of the piezoelectric plate on the second surface of the wafer; ,
a contour etching step of wet etching the wafer through the first contour mask and the second contour mask;
Equipped with
performing the outer shape mask forming step and the outer shape etching step before the first etching step;
The method for manufacturing a piezoelectric vibrating piece according to claim 1.

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