JP2018148380A - Piezoelectric vibration piece and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric vibration piece and a manufacturing method thereof that make it easy to manage groove depth dimension and stabilize oscillation and frequency.SOLUTION: A piezoelectric vibration piece 3 is provided with a first groove portion 36 and a second groove portion 37 on a pair of vibrating arm portions 31 and 32. The first groove portion and the second groove portion have a first parallel portion 51, a second parallel portion 52, a first inclined portion 53, a second inclined portion 54, and a groove bottom portion 55. The groove bottom portion is formed to have a predetermined groove width dimension W1. The first inclined portion extends obliquely from one side 55a of the groove bottom portion toward an opening 36a side up to a base end 51a of the first parallel portion. The second inclined portion extends obliquely from another side 55b of the groove bottom portion toward the opening 36a side up to a base end 52a of the second parallel portion.SELECTED DRAWING: Figure 3

Description

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

For example, in a mobile phone or a portable information terminal device, a piezoelectric vibrator using a crystal or the like is used as a device used for a time source, a timing source such as a control signal, a reference signal source, or the like. As this type of piezoelectric vibrator, a piezoelectric vibrator in which a piezoelectric vibrating piece is hermetically sealed in a package in which a cavity is formed is known.
Piezoelectric vibrators have been downsized year by year, and there is a need for smaller ones that can stabilize oscillation and frequency. Known as a piezoelectric vibrating piece used for a small piezoelectric vibrator is a supporting arm portion extending in parallel with the vibrating arm portion and having a weight portion (hammer head) formed at the tip of the vibrating arm portion. (For example, refer to Patent Document 1).
The vibrating arm portion of the piezoelectric vibrating piece is processed by, for example, wet etching.

Japanese Patent No. 058882525

However, the above prior art has the following problems.
When the groove is formed on the main surface of the vibrating arm, when the groove is processed by wet etching, the groove is formed in a V-shaped groove characteristic of anisotropic etching of quartz. For this reason, the electric field generated between the electrode of the groove portion and the electrode on the side surface of the vibrating arm portion is slightly different according to the shape of the V-shaped groove. Therefore, it is very difficult to obtain a stable vibration. In particular, when the aspect ratio of the groove portion increases, the V-shaped groove shape becomes conspicuous.
As a countermeasure, there is a method of processing the groove part by dry etching, but it becomes difficult to manage the groove depth dimension of the groove part by dry etching.

  The present invention has been made in view of such circumstances, and an object of the present invention is to easily manage the groove depth dimension of the groove portion, and to provide a piezoelectric vibrating piece that is stable in oscillation and frequency, and a method of manufacturing the piezoelectric vibrating piece Is to provide.

  In order to solve the above problems, a piezoelectric vibrating piece according to one aspect of the present invention includes a pair of vibrating arm portions extending from a base portion, and a groove portion that is opened along a main surface of the vibrating arm portion is formed. In the piezoelectric vibrating piece, the groove has an aspect ratio set to 0.7 or more, a groove bottom formed in a predetermined groove width dimension in the width direction of the main surface, and the opening from the side of the groove bottom. And an inclined portion extending in an inclined manner to the side wall portion of the groove portion toward the side.

According to this configuration, the groove bottom portion and the inclined portion are formed in the groove portion having an aspect ratio of 0.7 or more. The groove bottom is formed in a predetermined groove width dimension in the width direction of the main surface of the vibrating arm. By forming the groove bottom portion with a predetermined groove width dimension, the side wall portion from the main surface to the inclined portion can be extended in parallel along the side surface of the vibrating arm portion. Hereinafter, the side wall part from the opening of the groove part to the inclined part is referred to as a parallel part.
By extending the parallel portion in parallel along the side surface of the vibrating arm portion from the main surface to the inclined portion, the thickness from the parallel portion to the inclined surface is formed to have an even thickness dimension. Therefore, the electric field applied between the excitation electrode provided on the side surface and the excitation electrode provided in the groove is constant, and the vibration arm portion can obtain stable vibration. Thereby, the oscillation and frequency of the piezoelectric vibrating piece can be stabilized.
Moreover, the inclined part was extended in an inclined shape from the side of the groove bottom part to the side wall part. Therefore, compared with the case where a parallel part is directly connected with a groove bottom part, it can suppress that a stress concentrates on the edge part of a parallel part. Thereby, the impact resistance of the vibrating arm portion (that is, the piezoelectric vibrating piece) can be enhanced.

In the above aspect, a width dimension of the vibrating arm portion may be 60 μm or less.
According to this configuration, a small piezoelectric vibrating piece can be obtained by setting the width dimension of the vibrating arm portion to 60 μm or less.

In the above aspect, at least two of the groove portions may be formed along the main surface of the vibrating arm portion.
According to this configuration, by forming two groove portions on the main surface of the vibrating arm portion, it is possible to provide a piezoelectric vibrating piece having a low CI value while suppressing a decrease in the Q value.

  In the above aspect, the inclined portion includes a first inclined portion formed on one side of the groove bottom and a second inclined portion formed on the other side of the groove bottom, The width dimension of the one inclined part and the second inclined part in the groove width direction may be the same.

According to this configuration, the first inclined portion and the second inclined portion can be approximated by making the first inclined portion and the second inclined portion have the same width dimension. The side wall portion on the first inclined portion side is formed to have a uniform thickness. The side wall portion on the second inclined portion side is formed to have a uniform thickness.
Therefore, the electric field applied between the excitation electrode provided on the side wall portion on the first inclined portion side and the excitation electrode provided on the one side surface of the vibrating arm portion is constant. In addition, the electric field applied between the excitation electrode provided on the side wall portion on the second inclined portion side and the excitation electrode provided on the other side surface of the vibrating arm portion is constant. Thereby, the vibration arm portion can obtain stable vibration, and can stabilize the oscillation and frequency of the piezoelectric vibrating piece.

  In order to solve the above problems, a method of manufacturing a piezoelectric vibrating piece according to one aspect of the present invention is a method of manufacturing a piezoelectric vibrating piece by separately forming a piezoelectric vibrating piece having a vibrating arm portion from a substrate made of a piezoelectric material. Then, the outer shape of the piezoelectric vibrating piece is processed by dry etching to separate the piezoelectric vibrating piece from the substrate, and the groove portion opened in the main surface of the vibrating arm portion is dry etched to an intermediate depth. A first groove processing step for processing, and a second groove processing step for forming the groove portion by wet etching the groove portion processed to the intermediate depth, wherein the groove portion is in the width direction of the main surface. A groove bottom formed in a predetermined groove width dimension, and an inclined portion extending in an inclined manner from a side of the groove bottom toward the opening toward the side wall of the groove.

Here, in the small piezoelectric vibrating piece, the vibrating arm portion is also formed small. For this reason, the width dimension of the groove part formed in a vibrating arm part is restrained small. Further, when the aspect ratio of the groove is high, the groove depth dimension is larger than the groove width dimension. The aspect ratio is the ratio of the groove depth dimension to the groove width dimension.
When the aspect ratio of the groove is high, it is difficult to form the side wall of the groove in parallel along the side surface of the vibrating arm by wet etching.

Therefore, according to this configuration, in the first groove processing step, the groove is processed to a halfway depth by dry etching. Therefore, the side wall portion of the groove portion can be formed in parallel along the side surface of the vibrating arm portion.
Furthermore, in the second groove processing step, the groove portion processed to a halfway depth is processed by wet etching to form the groove portion. Therefore, the control of the groove depth dimension of the groove part becomes easier than dry etching.
Moreover, the side wall part (henceforth a parallel part) of a groove part can be formed in parallel along the side surface of a vibrating arm part. Therefore, the electric field applied between the excitation electrode provided on the side surface of the vibrating arm portion and the excitation electrode provided in the groove portion becomes constant, and the vibrating arm portion can obtain stable vibration. Thereby, the oscillation and frequency of the piezoelectric vibrating piece can be stabilized.

  In addition, in the second groove processing step, the groove is processed by wet etching. Therefore, an inclined part can be formed in the groove part. Thereby, compared with the case where a parallel part is directly connected with a groove bottom part, it can suppress that stress concentrates on the edge part of a parallel part. That is, the impact resistance of the vibrating arm portion (that is, the piezoelectric vibrating piece) can be improved.

  In the above aspect, the groove portion may have an aspect ratio of 0.7 or more.

According to this configuration, even when the aspect ratio of the groove is a high aspect ratio of 0.7 or more, the groove depth dimension of the groove can be easily managed by combining dry etching and wet etching, and A groove bottom part and an inclined part can be formed in the groove part.
A parallel part can be formed by forming a groove bottom part in a groove part. As a result, even when a groove portion having a high aspect ratio is formed in the vibrating arm portion, the vibrating arm portion can obtain stable vibration.
Further, by forming the inclined portion in the groove portion, it is possible to suppress the concentration of stress on the end portion of the parallel portion. Thereby, the impact resistance of the vibrating arm portion (that is, the piezoelectric vibrating piece) can be enhanced.

According to one aspect of the piezoelectric vibrating piece of the present invention, the groove bottom portion and the inclined portion are formed in the groove portion having an aspect ratio of 0.7 or more. Thereby, the oscillation and frequency of the piezoelectric vibrating piece can be stabilized.
In addition, according to one aspect of the method for manufacturing a piezoelectric vibrating piece of the present invention, the groove is formed by wet etching after dry etching. Thereby, the groove depth dimension of a groove part can be managed easily, and also the oscillation and frequency of a piezoelectric vibrating piece can be stabilized.

It is a perspective view which shows the state which decomposed | disassembled the piezoelectric vibrator which concerns on this invention. It is a top view which shows the state which attached the piezoelectric vibrating piece to the recessed part of the package main body which concerns on this invention. It is sectional drawing along the III-III line of FIG. 2 which shows the vibrating arm part which concerns on this invention. It is sectional drawing which shows the state by which the 1st excitation electrode and the 2nd excitation electrode were provided in the vibrating arm part which concerns on this invention. It is sectional drawing explaining the external shape process which dry-processes the external shape of a pair of vibrating arm part based on this invention. It is sectional drawing explaining the 1st groove processing process and the 2nd groove processing process which form a 1st groove part and a 2nd groove part in a pair of vibrating arm part which concerns on this invention.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.
[Piezoelectric vibrator]
FIG. 1 is a perspective view showing an exploded state of a piezoelectric vibrator 1 according to the present invention.
As shown in FIG. 1, the piezoelectric vibrator 1 is a so-called ceramic package type surface mount vibrator. The piezoelectric vibrator 1 includes a package 2 having a cavity C hermetically sealed therein, and a piezoelectric vibrating piece 3 accommodated in the cavity C.
Note that the outer shape of the piezoelectric vibrator 1 is formed in a substantially rectangular parallelepiped shape. Hereinafter, the longitudinal direction of the piezoelectric vibrator 1 is referred to as a longitudinal direction L, and the short side direction is referred to as a width direction W. Further, a direction orthogonal to the longitudinal direction L and the width direction W is referred to as a thickness direction T.

<Package>
The package 2 has a recess 17 that accommodates the piezoelectric vibrating piece 3. The package 2 includes a package body 5 and a sealing plate (lid) 6 that is bonded to the package body 5 and forms a cavity C between the package body 5 and the package body 5.
The package body 5 includes a first base substrate 10, a second base substrate 11, and a third base substrate 12 that are joined in a state of being overlapped with each other, and a seal ring 13 that is joined onto the third base substrate 12. ing.

The first base substrate 10, the second base substrate 11, and the third base substrate 12 are formed in a box shape that opens upward (that is, one in the thickness direction T). The first base substrate 10, the second base substrate 11, and the third base substrate 12 are made of a ceramic material and are integrally laminated in the thickness direction T. In addition, as a ceramic material used for each board | substrate 10-12, it is possible to use HTCC made from alumina, LTCC made from glass ceramics, etc., for example.
HTCC is an abbreviation for High Temperature Co-Fired Ceramic. LTCC is an abbreviation for Low Temperature Co-Fired Ceramic.

The upper surface 10 a of the first base substrate 10 forms the bottom surface of the recess 17.
The second base substrate 11 has a penetrating part 11a. The inner side surface of the penetrating portion 11a constitutes a part of the side wall of the cavity C. Mount portions 14 </ b> A and 14 </ b> B projecting inward are provided on the inner side surfaces of both sides of the penetrating portion 11 a in the width direction W. Mount parts 14A and 14B are formed in the approximate center of longitudinal direction L of penetration part 11a.

  A pair of electrode pads 20A and 20B that are connection electrodes to the piezoelectric vibrating piece 3 are formed on the upper surfaces of the mount portions 14A and 14B. The pair of electrode pads 20A and 20B is indicated by “///” (shaded portion). A pair of external electrodes 21 </ b> A and 21 </ b> B are formed on the lower surface of the first base substrate 10 at intervals in the longitudinal direction L. The electrode pads 20A and 20B and the external electrodes 21A and 21B are, for example, a single-layer film made of a single metal formed by vapor deposition or sputtering, or a stacked film in which different metals are stacked. Each is conducting.

  Similar to the second base substrate 11, the third base substrate 12 is formed with a through portion 12 a. A recess 17 is formed by the upper surface 10 a of the first base substrate 10, the penetrating portion 11 a of the second base substrate 11, and the penetrating portion 12 a of the third base substrate 12.

The seal ring 13 is a conductive frame-like member that is slightly smaller than the outer shape of the first base substrate 10, the second base substrate 11, and the third base substrate 12. The seal ring 13 is bonded to the upper surface of the third base substrate 12.
Specifically, the seal ring 13 is bonded onto the third base substrate 12 by baking with a brazing material such as silver brazing or a solder material. Alternatively, the seal ring 13 is joined by welding or the like to a metal joining layer formed on the third base substrate 12 (for example, by electroplating or electroless plating, or by vapor deposition or sputtering).

  The sealing plate 6 is stacked on the seal ring 13 and is airtightly bonded to the package body 5 by bonding to the seal ring 13. The space defined by the sealing plate 6, the seal ring 13, and the recess 17 functions as a cavity C hermetically sealed.

<Piezoelectric vibrating piece>
FIG. 2 is a plan view showing a state in which the piezoelectric vibrating piece 3 is attached to the recess 17 of the package body 5 according to the present invention.
As shown in FIG. 2, the piezoelectric vibrating piece 3 is a vibrating piece formed of a piezoelectric material such as quartz, lithium tantalate, or lithium niobate, and vibrates when a predetermined voltage is applied. In the following description, quartz will be described as an example of the piezoelectric material. In addition, the longitudinal direction L, the width direction W, and the thickness direction T of the piezoelectric vibrator 1 coincide with the longitudinal direction, the width direction, and the thickness direction of the piezoelectric vibrating piece 3. Therefore, in the following description, the same reference numerals as those of the longitudinal direction L, the width direction W, and the thickness direction T of the piezoelectric vibrator 1 are attached to the longitudinal direction, the width direction, and the thickness direction of the piezoelectric vibrating piece 3. To explain.

  The piezoelectric vibrating piece 3 is a so-called side arm type vibrating piece. Specifically, the piezoelectric vibrating piece 3 includes a pair of vibrating arm portions 31 and 32, a base portion 35 that connects the pair of vibrating arm portions 31 and 32, and a pair of support arm portions 33 that are connected to the base portion 35. 34.

  The pair of vibrating arm portions 31 and 32 extend along the longitudinal direction L and are arranged side by side so as to be parallel to each other. The pair of vibrating arm portions 31 and 32 vibrate with the base ends 31b and 32b as fixed ends and the tips 31a and 32a as free ends. The pair of vibrating arm portions 31 and 32 is, for example, a so-called hammer head type in which the width dimensions of the tips 31a and 32a are enlarged. The ends 31a and 32a of the pair of vibrating arm portions 31 and 32 are increased in weight and moment of inertia during vibration. Accordingly, the pair of vibrating arm portions 31 and 32 can easily vibrate, the length of the pair of vibrating arm portions 31 and 32 can be shortened, and the size can be reduced. In this embodiment, a pair of hammer arm type vibration arm portions 31 and 32 will be described as an example. However, the pair of vibration arm portions 31 and 32 is not limited to the hammer head type.

Of the pair of vibrating arm portions 31 and 32, one vibrating arm portion 31 is formed with a first groove portion 36 and a second groove portion 37 (see also FIG. 3). The first groove portion 36 and the second groove portion 37 are recessed in the thickness direction T and extended along the longitudinal direction L on both main surfaces 41 and 42 (see FIG. 3) of one vibrating arm portion 31. . The first groove portion 36 and the second groove portion 37 are formed from the base end 31b of one vibrating arm portion 31 to a portion where the width on the tip 31a side is enlarged.
The other vibrating arm portion 32 is formed with a first groove portion 38 and a second groove portion 39. The first groove portion 38 and the second groove portion 39 are recessed in the thickness direction T and extended along the longitudinal direction L on both main surfaces of the other vibrating arm portion 32. The first groove portion 38 and the second groove portion 39 are formed from the base end 32b of the other vibrating arm portion 32 to the portion where the width on the tip end 32a side is enlarged.

  The pair of vibrating arm portions 31 and 32 are provided with two systems of a first excitation electrode 57 and a second excitation electrode 58 (see FIG. 4) that vibrate the pair of vibrating arm portions 31 and 32 in the width direction W. . The excitation electrodes 57 and 58 are patterned in a state of being electrically insulated from each other, and are arranged so that the pair of vibrating arm portions 31 and 32 can vibrate at a predetermined frequency.

  The base ends 31 b and 32 b of the pair of vibrating arm portions 31 and 32 are connected to the base portion 35. The base portion 35 extends in the width direction W to the outside of the pair of vibrating arm portions 31 and 32. To the base portion 35, base ends 31b and 32b of the pair of vibrating arm portions 31 and 32 are integrally connected and fixed. The pair of support arm portions 33 and 34 are connected to both ends in the width direction W of the base portion 35 on both outer sides of the pair of vibrating arm portions 31 and 32, respectively.

  The pair of support arm portions 33, 34 extend in parallel to each other along the same longitudinal direction L as the extension direction of the pair of vibrating arm portions 31, 32 from the base portion 35. The support arm portion 33 is fixed to the electrode pad 20 </ b> A with the conductive adhesive 22. The support arm portion 34 is fixed to the electrode pad 20B with the conductive adhesive 22. As a result, the piezoelectric vibrating reed 3 is mounted on the electrode pad 20A and the electrode pad 20B of the package body 5.

  The pair of vibrating arm portions 31 and 32 are formed symmetrically about the center line of the piezoelectric vibrating piece 3 in the W direction. Therefore, of the pair of vibrating arm portions 31 and 32, one vibrating arm portion 31 will be described as the vibrating arm portion 31, and detailed description of the other vibrating arm portion 32 will be omitted.

FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2 showing the vibrating arm portion 31 according to the present invention.
As shown in FIG. 3, the vibrating arm portion 31 includes a first main surface 41, a second main surface 42 provided on the opposite side of the first main surface 41, a first main surface 41, and a second main surface 42. The first side surface 43 and the second side surface 44 are connected to each other. A first groove portion 36 is formed in the first main surface 41. A second groove portion 37 is formed on the second main surface 42. Therefore, the vibrating arm portion 31 is formed in an H-shaped cross section.

The first groove portion 36 includes a first parallel portion 51, a second parallel portion 52, a first inclined portion 53, a second inclined portion 54, and a groove bottom portion 55.
The first groove 36 is a high aspect ratio groove whose aspect ratio is set to 0.7 or more. The aspect ratio is (groove depth dimension D1 / groove width dimension of the opening 36a). The first groove portion 36 has a groove depth dimension D <b> 1 from the first main surface 41 to the groove bottom portion 55.
The reason why the aspect ratio of the first groove 36 is set to a high aspect ratio of 0.7 or more will be described in detail later.

The groove bottom 55 is formed such that the groove width dimension W1 of the first main surface 41 is a predetermined width in the width direction W. A first inclined portion 53 is formed on one side 55 a of the groove bottom portion 55. The first inclined portion 53 extends from the one side 55a toward the opening 36a side of the first groove portion 36 to the base end 51a of the first side wall portion 51 in an inclined manner.
By forming the groove bottom portion 55 having the groove width dimension W <b> 1 in the first groove portion 36, the first side wall portion 51 extends in parallel along the first side surface 43. Hereinafter, the first side wall portion 51 is referred to as a first parallel portion 51.

A second inclined portion 54 is formed on the other side 55 b of the groove bottom portion 55. The second inclined portion 54 extends in an inclined manner from the other side 55 b toward the opening 36 a side of the first groove portion 36 to the base end 52 a of the second side wall portion 52.
By forming the groove bottom portion 55 having the groove width dimension W <b> 1 in the first groove portion 36, the second side wall portion 52 extends in parallel along the second side surface 44. Hereinafter, the second side wall portion 52 is referred to as a second parallel portion 52.

The first parallel portion 51 has a depth dimension D2 from the first major surface 41 to the base end 51a on the groove bottom 55 side. Further, the second parallel portion 52 has a depth dimension D3 from the first main surface 41 to the base end 52a on the groove bottom 55 side.
The depth dimension D2 of the first parallel part 51 is set to 75% or more of the groove depth dimension D1 of the first groove part 36, for example. The depth dimension D3 of the second parallel portion 52 is set to 75% or more of the groove depth dimension D1 of the first groove portion 36, for example.

  In the embodiment, the depth dimension D2 of the first parallel part 51 and the depth dimension D3 of the second parallel part 52 are set to 75% or more of the groove depth dimension D1 of the first groove part 36. Although described, the present invention is not limited to this, and other depth dimensions can also be formed.

The first parallel part 51 is formed in parallel with the first side surface 43 as described above. Therefore, the first thickness between the first parallel portion 51 and the first side surface 43 is formed to have an equal thickness dimension T1. The second parallel part 52 is formed in parallel with the second side surface 44 as described above. Therefore, the second thickness between the second parallel portion 52 and the second side surface 44 is formed to have an equal thickness dimension T2.
Moreover, the thickness dimension T1 of the first thickness and the thickness dimension T2 of the second thickness are formed in the same dimension.

  The second groove portion 37 is formed symmetrically with the first groove portion 36 around the central portion 56 between the first main surface 41 and the second main surface 42. Therefore, the same reference numerals as those of the constituent portions of the first groove portion 36 are assigned to the constituent portions of the second groove portion 37, and detailed description thereof is omitted.

FIG. 4 is a sectional view showing a state in which the first excitation electrode 57 and the second excitation electrode 58 are provided on the pair of vibrating arm portions 31 and 32 according to the present invention.
The first excitation electrode 57 and the second excitation electrode 58 of the vibrating arm portion 31 are patterned in a state where they are electrically insulated from each other. By applying a potential to the first excitation electrode 57 and the second excitation electrode 58, an electric field is generated from the first parallel portion 51 of the first groove portion 36 to the first side surface 43, and the second parallel portion 52 of the first groove portion 36 An electric field is generated on the two side surfaces 44.
The vibrating arm portion 31 has a characteristic (referred to as electrostriction characteristic) that expands and contracts in a certain direction when an electric field is generated in a certain direction. As a result, the vibration arm portion 31 is distorted by electrostriction characteristics to generate vibration, and the pair of vibration arm portions 31 and 32 can be vibrated in the width direction W.

Here, in the vibrating arm portion 31, the first parallel portion 51 is formed in parallel with the first side surface 43, and the first thickness is formed to have an equal thickness dimension T1. Further, the second parallel portion 52 is formed in parallel with the second side surface 44, and the second thickness is formed to an equal thickness dimension T2. Furthermore, the thickness dimension T1 of the first thickness and the thickness dimension T2 of the second thickness are formed to the same dimension.
As a result, the electric field applied between the first excitation electrode 57 and the second excitation electrode 58 becomes constant, and the vibrating arm portion 31 can obtain stable vibration.

The other vibrating arm portion 32 is formed symmetrically about the center line of the vibrating arm portion 31 and the piezoelectric vibrating piece 3 in the W direction. Therefore, the first excitation electrode and the second excitation electrode of the other vibrating arm portion 32 are denoted by the same reference numerals as those of the first excitation electrode 57 and the second excitation electrode 58 of the vibrating arm portion 31, and detailed description thereof is omitted. Also in the other vibrating arm portion 32, the electric field applied between the first excitation electrode 57 and the second excitation electrode 58 is constant, and the other vibrating arm portion 32 can obtain stable vibration.
Thereby, the oscillation and frequency of the piezoelectric vibrating piece 3 can be stabilized.

Returning to FIG. 3, the base end 51 a of the first parallel portion 51 and the one side 55 a of the groove bottom portion 55 are connected to each other by the first inclined portion 53 in an inclined manner. The base end 52 a of the second parallel part 52 and the other side 55 b of the groove bottom part 55 are connected in an inclined manner by the second inclined part 54.
Therefore, compared with the case where the first parallel part 51 and the second parallel part 52 are directly connected to the groove bottom part 55, stress is applied to the base end 51a of the first parallel part 51 and the base end 52a of the second parallel part 52. Concentration can be suppressed.
Thereby, the impact resistance of the vibrating arm portion 31 (that is, the piezoelectric vibrating piece 3) can be improved.

Next, a manufacturing method of the piezoelectric vibrating piece 3 forming the pair of vibrating arm portions 31 and 32 according to the present invention will be described with reference to FIGS.
5 and 6, the pair of vibrating arm portions 31 and 32 are manufactured in the same manner. Therefore, in order to facilitate understanding of the manufacturing method of the piezoelectric vibrating piece 3, one vibrating arm portion 31 of the pair of vibrating arm portions 31 and 32 will be described in detail, and a detailed description of the other vibrating arm portion 32 will be given. Omitted.

FIG. 5 is a cross-sectional view for explaining an outer shape processing step for dry etching the outer shape of the pair of vibrating arm portions 31 and 32 according to the present invention.
In the masking process of FIG. 5A, the etching protection film 63 is formed by masking the front surface 61a and the back surface 61b of the substrate 61 made of piezoelectric material with Cr (chromium). Hereinafter, the etching protection film 63 subjected to the masking process with Cr is referred to as a Cr mask 63.
An etching protective film 64 is formed by performing a masking process of Au (gold) on the Cr mask 63 and the substrate 61 between the Cr mask 63 and the Cr mask 63. Hereinafter, the etching protection film 64 subjected to the masking process with Au is referred to as an Au mask 64.

5B, the pair of vibrating arm portions 31 and 32 are separated from the substrate 61 by processing the outer shape of the pair of vibrating arm portions 31 and 32 by dry etching.
For example, the pair of vibrating arm portions 31 and 32 is dry-etched using a fluorine-based gas such as carbon tetrafluoride.

  In the step of removing the Au mask 64 in FIG. 5C, the Au mask 64 is removed from the pair of vibrating arm portions 31 and 32 separated from the substrate 61 (see FIG. 5A). Only the Cr mask 63 is left on the pair of vibrating arm portions 31 and 32.

  FIG. 6 shows the first groove processing in which the first groove portion 36 and the second groove portion 37 are formed in one vibration arm portion 31 according to the present invention, and the first groove portion 38 and the second groove portion 39 are formed in the other vibration arm portion 32. It is sectional drawing explaining a process and a 2nd groove | channel process process.

In the first groove machining step of FIG. 6A, the first groove 36 is machined to a midway depth by dry etching on the first main surface 41 of one vibrating arm 31. The first parallel part 51 and the second parallel part 52 of the first groove part 36 extend from the first main surface 41 of one vibrating arm part 31 to the middle of the groove bottom part 55 (see FIG. 6B) of the first groove part 36. Processed by dry etching.
Thereby, the first parallel part 51 is processed in parallel along the first side surface 43 of the one vibrating arm part 31 until halfway. Further, the second parallel portion 52 is processed in parallel along the second side surface 44 of the one vibrating arm portion 31 until halfway.

The second groove portion 37 is processed to a halfway depth on the second main surface 42 of the one vibrating arm portion 31 by dry etching. The first parallel part 51 and the second parallel part 52 of the second groove part 37 extend from the second main surface 42 of the pair of vibrating arm parts 31 and 32 to the groove bottom part 55 of the second groove part 37 (see FIG. 6B). Processed by dry etching halfway.
Thereby, the first parallel part 51 is processed in parallel along the first side surface 43 of the one vibrating arm part 31 until halfway. Further, the second parallel portion 52 is processed in parallel along the second side surface 44 of the one vibrating arm portion 31 until halfway.

  In particular, in the small piezoelectric vibrating piece, the vibrating arm portion is also formed in a small size. As an example, the width of the small vibrating arm is formed to be 60 μm or less. Therefore, the aspect ratio of the first groove part 36 and the second groove part 37 is increased. That is, the groove depth dimension is larger than the groove width dimension. Therefore, in the wet etching, the groove portion is formed in a V-shaped groove shape peculiar to anisotropic etching of quartz. For this reason, it becomes difficult to form the first parallel part 51 and the second parallel part 52 along the first side face 43 and the second side face 44 in parallel.

Therefore, the first groove portion 36 and the second groove portion 37 are processed to a halfway depth by dry etching. Therefore, the first parallel portion 51 and the second parallel portion 52 can be formed in parallel along the first side surface 43 and the second side surface 44.
As an example, the first groove portion 36 and the second groove portion 37 are processed to a depth of 70% of the groove depth dimension D1 (see FIG. 3) by dry etching.

In the second groove processing step of FIG. 6B, for example, in one vibrating arm 31, the remaining 30% of the first groove 36 processed to a halfway depth is processed by wet etching to form the first groove 36. To the end. For example, wet etching is performed by immersing the pair of vibrating arm portions 31 and 32 in a chemical solution (iodine).
The remaining portions of the first parallel portion 51 and the second parallel portion 52 of the first groove portion 36 are formed by wet etching. Further, the first inclined portion 53, the second inclined portion 54, and the groove bottom portion 55 are processed by wet etching to form the first groove portion 36.

Here, after the first groove portion 36 is processed to a halfway depth by dry etching, the first groove portion 36 is processed to the end by wet etching, whereby the groove bottom portion 55 has a predetermined width of the groove width dimension W1 (see FIG. 3). Can be formed.
Thereby, the remaining site | parts of the 1st parallel part 51 can be formed in parallel along the 1st side surface 43 by wet etching. Further, the remaining portion of the second parallel portion 52 can be formed in parallel along the second side surface 44 by wet etching.

  Further, in the one vibrating arm portion 31, the second groove portion 37 is formed by wet etching the second groove portion 37 that has been processed to a halfway depth. The remaining portions of the first parallel portion 51 and the second parallel portion 52 of the second groove portion 37 are formed by wet etching. Further, the first inclined portion 53, the second inclined portion 54, and the groove bottom portion 55 are processed by wet etching to form the second groove portion 37.

Further, after the second groove portion 37 is processed to a halfway depth by dry etching, the second groove portion 37 is processed to the end by wet etching, so that the groove bottom portion 55 has a predetermined width of the groove width dimension W1 (see FIG. 3). Can be formed.
Thereby, the remaining site | parts of the 1st parallel part 51 can be formed in parallel along the 1st side surface 43 by wet etching. Further, the remaining portion of the second parallel portion 52 can be formed in parallel along the second side surface 44 by wet etching.
In this way, by processing the first groove portion 36 and the second groove portion 37 that have been processed to a halfway depth by wet etching, the management of the groove depth dimension D1 of the first groove portion 36 and the second groove portion 37 is compared to dry etching. Easier.

  In the embodiment, the example in which the first groove portion 36 and the second groove portion 37 are processed to a depth of 70% of the groove depth dimension D1 by dry etching and the remaining 30% is processed by wet etching has been described. Not what you want. The groove depth dimension processed by dry etching and the groove depth dimension processed by wet etching can be appropriately selected.

For example, dry etching may be processed to a depth of 90% or more, and the rest may be processed by wet etching. When the wet etching process is shortened, the anisotropy of the crystal is less likely to occur, and the first inclined portion 53 and the second inclined portion 54 have the same width dimension.
The width dimension of the 1st inclination part 53 and the 2nd inclination part 54 is demonstrated.

As shown in FIG. 3, the width dimension of the first inclined portion 53 refers to the upper end of the first inclined portion 53 (that is, the base end 51a of the first side wall portion 51) to the lower end of the first inclined portion 53 (that is, the groove). It is a dimension in the groove width direction along the groove bottom 55 between one side 55a) of the bottom 55.
The width dimension of the second inclined portion 54 refers to the upper end of the second inclined portion 54 (that is, the base end 52a of the second side wall portion 52) to the lower end of the second inclined portion 54 (that is, the other side of the groove bottom portion 55). 55b) is a dimension in the groove width direction along the groove bottom 55.
By making the width dimensions of the first inclined portion 53 and the second inclined portion 54 the same, the shapes of the first inclined portion 53 and the second inclined portion 54 are also approximated. The first parallel portion 51 is formed to have a thickness dimension T <b> 1 with the same thickness up to the first inclined portion 53. The second parallel part 52 is formed to have a thickness dimension T <b> 2 in which the thickness up to the second inclined part 54 is uniform.

  The thickness dimension T1 of the first thickness and the thickness dimension T2 of the second thickness are formed to be the same dimension. Therefore, the electric field applied between the excitation electrode 57 provided on the first side surface 43 and the excitation electrode 58 provided on the first groove portion 36 is constant. Further, the electric field applied between the excitation electrode 57 provided on the second side surface 44 and the excitation electrode 58 provided on the first groove portion 36 becomes constant. Thereby, the vibrating arm portion 31 can obtain a stable vibration, and can stabilize the oscillation and frequency of the piezoelectric vibrating piece 3.

In the step of removing the Cr mask 63 of FIG. 6C, the Cr mask 63 (see FIG. 6B) is removed from the one vibrating arm portion 31 in which the first groove portion 36 and the second groove portion 37 are formed.
Accordingly, the first groove portion 36 and the second groove portion 37 can be formed in one vibrating arm portion 31 of the piezoelectric vibrating piece 3 by the method for manufacturing the piezoelectric vibrating piece 3.
Similarly, the first groove portion 38 and the second groove portion 39 can be formed in the other vibrating arm portion 32 of the piezoelectric vibrating piece 3.

Thus, by processing the first groove portion 36, the second groove portion 37, etc. by wet etching after dry etching, it becomes possible to process a high aspect ratio groove portion having an aspect ratio of 0.7 or more.
The reason why the first groove part 36, the second groove part 37, etc. having a high aspect ratio with an aspect ratio of 0.7 or more are processed by combining dry etching and wet etching will be described with reference to FIG.

  That is, when the aspect ratio of the groove part is a high aspect ratio of 0.7 or more, when the groove part is processed only by wet etching, the groove part is formed into a V-shaped groove shape peculiar to anisotropic etching of quartz. For this reason, the groove bottom part 55 of the groove width dimension W1 cannot be formed like the first groove part 36 and the second groove part 37 of the embodiment. Therefore, the first parallel portion 51 and the second parallel portion 52 that are parallel to the first side surface 43 and the second side surface 44 cannot be formed. For this reason, it is difficult to stabilize the oscillation and frequency of the piezoelectric vibrating piece.

On the other hand, when a high aspect ratio groove portion having an aspect ratio of 0.7 or more is processed only by dry etching, the groove portion is formed in a state where the first inclined portion 53 and the second inclined portion 54 of the embodiment are removed. That is, when the groove portion is processed only by dry etching, the first parallel portion 51 and the second parallel portion 52 of the embodiment are directly connected to the groove bottom portion 55.
For this reason, a stress concentrates on the connection part of the 1st parallel part 51 and the groove bottom part 55, and the connection part of the 2nd parallel part 52 and the groove bottom part 55, and the device which ensures impact resistance is requested | required.
Furthermore, when the groove is processed only by dry etching, it is difficult to manage the depth of the groove.

Therefore, the first groove portion 36, the second groove portion 37, and the like are processed halfway by dry etching, and are processed from the middle to the end by wet etching.
Accordingly, the first parallel portion 51 and the second parallel portion 52 can be formed in the groove portion having a high aspect ratio with an aspect ratio of 0.7 or more, and the oscillation and frequency of the piezoelectric vibrating piece 3 can be stabilized. Thereby, for example, the width dimension of the vibrating arm portion can be set to 60 μm or less, and a small piezoelectric vibrating piece can be obtained.
Moreover, the 1st inclination part 53 and the 2nd inclination part 54 can be formed, and the impact resistance of the vibration arm part 31 (namely, piezoelectric vibration piece 3) can be improved. Furthermore, the management of the groove depth dimension D1 of the first groove part 36 and the second groove part 37 is easier than in dry etching.

The technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the so-called side arm type piezoelectric vibrating piece 3 has been described, but the present invention is not limited thereto. As another example, the present invention can be applied to a so-called center arm type piezoelectric vibrating piece. Furthermore, the present invention can also be applied to a piezoelectric vibrating piece of the type in which the base of the piezoelectric vibrating piece is joined to a package.

Moreover, although the said embodiment demonstrated the example which formed the 1st groove part 36 in the 1st main surface 41 of the vibration arm part 31, it is not limited to this. As another example, it is possible to form two groove portions in parallel on the first main surface 41 of the vibrating arm portion 31.
In this case, the width of the groove is further reduced, and the aspect ratio of the groove is further increased. As an example, the aspect ratio of each groove is as high as 4 or more. Even a groove portion having an aspect ratio of 4 or more can be processed by wet etching after dry etching, and the manufacturing method of the embodiment can be used more effectively.
By forming two groove portions on the first main surface 41 of the vibrating arm portion 31, it is possible to provide a piezoelectric vibrating piece having a low CI value while suppressing a decrease in the Q value.

DESCRIPTION OF SYMBOLS 1 ...... Piezoelectric vibrator 2 ......... Package 3 ...... Piezoelectric vibrating piece 31, 32 ... A pair of vibrating arm part 33, 34 ... A pair of support arm part 35 ... Base part 36, 38 ... First groove part ( Groove)
37, 39 ... Second groove (groove)
41 …… First main surface (main surface)
42 …… Second main surface (main surface)
43 …… First side (side)
44 …… Second side (side)
51 …… First parallel part (parallel part)
52 …… Second parallel part (parallel part)
51a, 52a ... end (end of parallel part)
53 …… First inclined part (inclined part)
54 …… Second inclined part (inclined part)
55... Groove bottom 55 a .. one side of groove bottom 55 b... Other side of groove bottom 61 .. substrate D 1 .. groove depth W 1 .. groove depth

Claims (6)

In the piezoelectric vibrating piece having a pair of vibrating arm portions extending from the base portion and having a groove portion opened along the main surface of the vibrating arm portion,
The groove is
The aspect ratio is set to 0.7 or higher,
A groove bottom formed in a predetermined groove width dimension in the width direction of the main surface;
A piezoelectric vibrating piece comprising: an inclined portion extending in an inclined manner from the side of the groove bottom toward the opening toward the side wall of the groove.   The piezoelectric vibrating piece according to claim 1, wherein a width dimension of the vibrating arm portion is 60 μm or less.   The piezoelectric vibrating piece according to claim 1, wherein at least two of the groove portions are formed along the main surface of the vibrating arm portion. The inclined portion is
A first inclined portion formed on one side of the groove bottom,
A second inclined portion formed on the other side of the groove bottom,
The piezoelectric vibrating piece according to any one of claims 1 to 3, wherein the first inclined portion and the second inclined portion have the same width dimension in the groove width direction. A method of manufacturing a piezoelectric vibrating piece for separating a piezoelectric vibrating piece having a vibrating arm from a substrate made of a piezoelectric material,
A separation process for separating the piezoelectric vibrating piece from the substrate by processing the outer shape of the piezoelectric vibrating piece by dry etching;
A first groove processing step of processing the groove portion opened in the main surface of the vibrating arm portion to a halfway depth by dry etching;
A second groove processing step in which the groove processed to the intermediate depth is processed by wet etching to form the groove, and
The groove is
A groove bottom formed in a predetermined groove width dimension in the width direction of the main surface;
A method of manufacturing a piezoelectric vibrating piece, comprising: an inclined portion extending in an inclined manner from a side of the groove bottom toward an opening toward a side wall of the groove.   The method for manufacturing a piezoelectric vibrating piece according to claim 5, wherein the groove portion has an aspect ratio set to 0.7 or more.

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