JP2008236335A - Piezoelectric vibration chip and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure stiffness of a vibration arm and to improve a stability of a vibration. <P>SOLUTION: A groove 36 extending in a direction of a straight side of a vibration arm 18 is formed in a first surface 12 and a second surface 14. The groove 36 includes a first inner surface 33 extending back on to a first side 32, a second inner surface 35 extending back on to a second side 34, a bottom surface 37 between the first inner surface 33 and the second inner surface 35, and a third inner surface 39 and a fourth inner surface 41 connected to both ends in the direction of the straight side of the bottom surface 37 and both ends in the direction of the straight side of the first and second inner surfaces 33 and 35. The first surface 33 and the second surface 35 of the groove 36 formed on the first surface 12 are nonparallel to each other, parallel to a straight side of a vibration arm 18, and is plane-symmetric with respect to a symmetric surface S<SB>1</SB>vertical to the first surface 12 and the second surface 14. The first inner surface 33 and the second inner surface 35 of the groove 36 formed on the second surface 14 are nonparallel to each other, and is plane-symmetric with respect to the symmetrical surface S<SB>1</SB>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

The tuning fork type piezoelectric vibrating piece has a pair of vibrating arms, and excitation electrodes are formed on the vibrating arms. Further, a groove is formed in the vibrating arm, and excitation electrodes are formed on the side surface of the vibrating arm and in the groove (Patent Document 1). According to this configuration, the electric field generated between the vibrating arm and the electrode in the groove can be used efficiently, and the CI value decreases. However, as shown in FIG. 4 of Patent Document 1, when the entire vibrating arm is formed by wet etching, the inclination angle of the opposing inner surface is not subject to right and left. Then, the vibrating arm vibrates in an oblique direction, and the vibration characteristics may not be stable. In order to solve this problem, there is also known a method in which the groove of the vibrating arm is formed by dry etching so that the groove has a U-shaped cross section. However, when the vibrating arm is downsized, the rigidity of the entire vibration is lowered, and there is a possibility that the vibration may be adversely affected due to insufficient rigidity around the joint between the groove bottom surface and the groove side surface.
JP 2006-352771 A

  An object of the present invention is to improve the vibration characteristics by securing the rigidity of the vibrating arm.

(1) The piezoelectric vibrating piece according to the present invention is
The base,
A pair of vibrating arms extending from the base;
An excitation electrode film formed on each of the vibrating arms;
Including
Each of the vibrating arms includes first and second parallel surfaces facing opposite to each other, and first and second sides connected substantially vertically to both sides of the first and second surfaces. Have
A groove extending in the longitudinal direction of the vibrating arm is formed on each of the first and second surfaces,
The groove includes a first inner surface extending back to back with the first side surface, a second inner surface extending back to back with the second side surface, and a bottom surface between the first and second inner surfaces,
The first and second inner surfaces of the groove formed on the first surface are non-parallel to each other, pass through the center in the width direction of the first and second surfaces, and the first and second surfaces. 2 is symmetric with respect to a plane of symmetry perpendicular to the surface of
The first and second inner surfaces of the groove formed on the second surface are non-parallel to each other and are plane-symmetric with respect to the symmetry plane. According to the present invention, since the first and second side surfaces are perpendicular to the first and second surfaces, the vibration efficiency of the vibrating arm is good. On the other hand, since the first and second inner surfaces of the groove are inclined, the rigidity can be ensured, and the first and second inner surfaces are formed with the bottom surface as compared with the case where the first and second inner surfaces are formed perpendicular to the first and second surfaces. There are few factors that reduce vibration efficiency because stress is difficult to concentrate on the corner. In addition, since the first and second inner surfaces are plane-symmetric, the vibration characteristics are stabilized.
(2) In this piezoelectric vibrating piece,
The bottom surface may be a convex curved surface.
(3) In this piezoelectric vibrating piece,
The groove further includes third and fourth inner surfaces connecting both ends of the first and second inner surfaces,
The third and fourth inner surfaces of the groove formed on the first surface are non-parallel to each other, and are second symmetrical with respect to the symmetry plane and perpendicular to the first and second surfaces. It is plane symmetric about the plane,
The third and fourth inner surfaces of the groove formed on the second surface may be non-parallel to each other and be symmetric with respect to the second symmetry plane.
(4) In this piezoelectric vibrating piece,
The first inner surface of the groove formed on the first surface and the second inner surface of the groove formed on the second surface have the same angle with respect to the symmetry plane,
The second inner surface of the groove formed on the first surface and the first inner surface of the groove formed on the second surface may have the same angle with respect to the symmetry plane. Good.
(5) A method for manufacturing a piezoelectric vibrating piece according to the present invention includes:
(A) a step of performing full etching by wet etching by partially covering the parallel front and back surfaces of the piezoelectric wafer facing each other partially with a wet etching resist;
(B) after the step (a), partially covering the front surface and the back surface with a dry etching resist and performing half etching by dry etching;
Including
The region covered with the wet etching resist includes a region for forming the first and second surfaces of the vibrating arm from a part of the front surface and the back surface,
The exposed region from the dry etching resist includes a region for forming a groove in the vibrating arm,
In the step (a), the first and second side surfaces of the vibrating arm connected to both sides of the first and second surfaces in the width direction are substantially the same as the first and second surfaces. Perform the wet etching so that it is vertical,
In the step (b), the first and second inner surfaces of the groove extending back to back with the first and second side surfaces are not parallel to each other and pass through the center of the vibrating arm in the width direction. In addition, the dry etching is performed so that the plane of symmetry perpendicular to the first and second surfaces is symmetrical. According to the present invention, a groove including the first and second inner surfaces that are plane-symmetric can be formed by dry etching.
(6) In the method of manufacturing the piezoelectric vibrating piece,
Forming the dry etching resist with Cr;
The dry etching may be performed so that the bottom surface of the groove has a convex curved surface.
(7) In this method of manufacturing a piezoelectric vibrating piece,
In the step (b), half etching is performed on the surface in a state where the dry etching resist is adhered to the front surface and the back surface, respectively, and then the dry etching resist is adhered to the front surface and the back surface, respectively. You may half-etch with respect to a back surface.
(8) In this method of manufacturing a piezoelectric vibrating piece,
The step (b)
In the state where the dry etching resist is attached to the front surface and the second protective film covering the back surface is attached, half etching is performed on the front surface, and then
Removing the dry etching resist on the front surface and the second protective film on the back surface;
In the state where the dry etching resist is attached to the back surface and the first protective film covering the groove on the surface and the surface is attached, half etching is performed on the back surface,
The method may include removing the dry etching resist on the back surface and the first protective film on the front surface.

  FIG. 1 is a plan view showing a piezoelectric vibrating piece according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view taken along the line II-II of the piezoelectric vibrating piece shown in FIG. 3 is an enlarged sectional view taken along line III-III of the piezoelectric vibrating piece shown in FIG. The bottom view appears symmetrically with the plan view.

  The piezoelectric vibrating piece (for example, a tuning fork type piezoelectric vibrating piece) is made of a piezoelectric material such as quartz, lithium tantalate, or lithium niobate. When the piezoelectric vibrating piece is made of quartz, the quartz wafer is cut out by rotating in the range of 0 to 5 degrees clockwise around the Z axis in an orthogonal coordinate system composed of the X, Y, and Z axes. A crystal Z plate obtained by cutting and polishing to a predetermined thickness is used. The piezoelectric vibrating piece includes a base portion 16 and a pair of vibrating arms 18 extending from the base portion 16.

  The base portion 16 is formed with a pair of cuts 22 in the opposing direction so that the shape confined to the first and second surfaces 12 and 14 appears. The base portion 16 includes first and second portions 24 and 26 located on both sides of the pair of cuts 22, and a connection portion 28 that connects the first and second portions 24 and 26 between the pair of cuts 22. And including. Since the transmission of the vibration of the vibrating arm 18 is cut off by the notch 22, the vibration is transmitted to the outside via the base 16 and the support arm 38, and loss of vibration energy (vibration leakage) is suppressed, and the CI value increases. Can be prevented. As the length (depth) of the notch 22 is longer (deeper) within a range in which the strength of the base portion 16 can be secured, the vibration leakage suppressing effect is larger. The width between the pair of cuts 22 (the width of the connecting portion 28) may be smaller or larger than the interval between the opposing side surfaces of the pair of vibrating arms 18, or the mutual distance between the pair of vibrating arms 18. The distance may be smaller or larger than the distance of the side surface facing the opposite direction.

  The pair of vibrating arms 18 extends from the first portion 24 of the base portion 16 in parallel to the first and second surfaces 12 and 14. The vibrating arm 18 includes parallel first and second surfaces 12 and 14 facing opposite to each other, and first and second side surfaces 32 connected vertically to both sides of the first and second surfaces 12 and 14. 34. When the piezoelectric vibrating piece is made of quartz, with respect to the crystal orientation, the first side surface 32 faces the + direction of the X axis, the second side surface 34 faces the − direction of the X axis, and extends from the base 16 along the + Y axis. Configure to extend.

  The resonating arm 18 is wide at the base portion connected to the base portion 16 toward the base portion 16 and is connected to the base portion 16 with a wide width, so that the rigidity is high. The width of the vibrating arm 18 defined by the distance between the first and second side surfaces 32 and 34 is narrowed from the base 16 toward the tip. By forming such a taper, the vibrating arm 18 is easily vibrated. However, the vibrating arm 18 is reverse-tapered at a position close to the tip so that the width increases toward the tip. By applying the reverse taper, the tip portion functions as a weight, so that the vibration frequency can be lowered. The vibrating arm 18 is formed so that the position where the taper is reversed to the reverse taper is located closer to the tip than the groove 36.

  The vibrating arm 18 is formed with grooves 36 extending in the longitudinal direction on the first and second surfaces 12 and 14, respectively. The groove 36 has a length of 50 to 70% of the length of the vibrating arm 18. Further, the groove 36 has a width of 60 to 90% of the width of the vibrating arm 18.

The groove 36 includes a first inner surface 33 extending back to back with the first side surface 32, and a second inner surface 35 extending back to back with the second side surface 34. The first and second inner surfaces 33 and 35 of the groove 36 formed in the first surface 12 are non-parallel to each other. Further, the first and second inner surfaces 33 and 35 are not perpendicular to the first surface 12. The first and second inner surfaces 33 and 35 are plane-symmetric with respect to a plane of symmetry S ₁ that is parallel to the longitudinal direction of the vibrating arm 18, passes through the centers of the first and second surfaces 12 and 14, and is perpendicular thereto. It has become. Similarly, the first and second inner surfaces 33 and 35 of the groove 36 formed in the second surface 14 is also a non-parallel to each other, which is the plane of symmetry for the symmetry plane S _1. The groove 36 includes a bottom surface 37 between the first and second inner surfaces 33, 35. The bottom surface 37 may be a convex curved surface or a flat surface.

The groove 36 includes third and fourth inner surfaces 39, 41 connected to both longitudinal ends of the bottom surface 37 and both longitudinal ends of the first and second inner surfaces 33, 35. The third and fourth inner surfaces 39 and 41 of the groove 36 formed in the first surface 12 are non-parallel to each other. Further, the third and fourth inner surfaces 39 and 41 are plane-symmetric with respect to a _second symmetry plane S ₂ that is orthogonal to the symmetry plane S ₁ and perpendicular to the first and second surfaces 12 and 14. The third and fourth inner surfaces 39 and 41 of the groove 36 formed in the second surface 14 are also non-parallel to each other and are plane-symmetric with respect to the _second symmetry plane S2.

A narrow angle to the first inner surface 33 and the plane of symmetry S ₁ is formed inside the groove 36, the second inner surface 35 and the plane of symmetry S ₁ and forms narrow angle the same, for example, 70 to 90 °. Similarly, the third inner surface, the fourth inner surface, a narrow angle formed between the second plane of symmetry S ₂ each are the same.

According to the present embodiment, the first and second inner surfaces 33 and 35 of the groove 36 are inclined, so that rigidity can be ensured. Therefore, compared to the case where the first and second inner surfaces 33, 35 are formed perpendicular to the first and second surfaces 12, 14, stress is less likely to concentrate on the corner formed by the bottom surface 37. There are few factors that adversely affect vibration. Moreover, the first and second side surfaces 32 and 34 are substantially perpendicular to the first and second surfaces 12 and 14, and the first and second inner surfaces 33 and 35 are plane-symmetric. because there, the entire vibrating arms are symmetrical with respect to the symmetry plane S _1. Therefore, it is possible to reduce the possibility of occurrence of oblique vibration including displacement in the z direction, and the vibration is stabilized.

  The piezoelectric vibrating piece has a pair of support arms 38 extending from the second portion 26 of the base 16. The pair of support arms 38 extend in directions opposite to the direction in which the pair of vibrating arms 18 extend from the base portion 16 and extend in directions opposite to each other, and further bend and extend in the direction in which the pair of vibrating arms 18 extends. By bending, the support arm 38 is miniaturized. The support arm 38 is a part that is attached to a package or the like (not shown), and the vibration arm 18 and the base 16 are brought into a floating state by the attachment with the support arm 38.

  An excitation electrode film 40 is formed on the vibrating arm 18. The excitation electrode film 40 shown in FIG. 2 is composed of one layer, and is a base Cr film having a thickness of 100 to 300 mm, and an Au film having a thickness of 200 to 500 mm formed on the Cr film. A multilayer structure including It is known that the Cr film has high adhesion to quartz, and the Au film has low electrical resistance and is difficult to oxidize. The excitation electrode film 40 includes front and back electrode films (a plurality of front electrode films and a plurality of back electrode films) formed on the first and second surfaces 12 and 14, and the first and second side surfaces 32 and 34, respectively. First and second side electrode films formed respectively, and an inner surface electrode film formed on the inner surface of the groove 36 are included.

  The excitation electrode film 40 constitutes first and second excitation electrodes 42 and 44. In one vibrating arm 18, the voltage is applied between the first and second excitation electrodes 42 and 44, and the first and second side surfaces 32 and 34 of the vibrating arm 18 are expanded and contracted to vibrate the vibrating arm 18. Let By forming the groove 36, the z-direction component of the electric field generated between the excitation electrodes 42 and 44 is reduced, and the x-direction component is increased. Therefore, the electric field can be used more efficiently than when no groove is provided, and the CI value can be lowered. It is known that the CI value of the first and second excitation electrodes 42 and 44 decreases as the length increases to 70% of the vibrating arm 18.

  The first excitation electrode 42 includes an inner surface electrode film formed on the inner surface of the groove 36. The inner surface electrode film formed in the groove 36 of the first surface 12 and the inner surface electrode film formed in the groove 36 of the second surface 14 are electrically connected. In other words, the pair of first excitation electrodes 42 formed on the first and second surfaces 12 and 14 are electrically connected. A pair of first excitation electrodes 42 formed on one vibrating arm 18 is connected to extraction electrodes 46 formed on the first and second surfaces 12 and 14 on the base 16, respectively. Are electrically connected by being connected to the first or second side electrode film of the other vibrating arm 18.

  The second excitation electrode 44 includes first and second side surface electrode films formed on the first and second side surfaces 32 and 34. The first and second side electrode films are electrically connected. The electrical connection is achieved by connecting electrodes 48 formed on at least one (or both) of the first and second surfaces 12 and 14 at a portion (for example, the tip) of the vibrating arm 18 where the groove 36 is not formed. Is made by.

  The first excitation electrode 42 formed on one vibrating arm 18 and the second excitation electrode 44 formed on the other vibrating arm 18 are electrically connected by a lead electrode 46 on the base 16. . The extraction electrode 46 is formed up to the support arm 38 arranged next to the vibrating arm 18 where the second excitation electrode 44 is formed. The extraction electrode 46 may be formed on the first and second surfaces 12 and 14 (or further side surfaces) of the support arm 38. On the support arm 38, the extraction electrode 46 can be an electrical connection portion with the outside.

  FIG. 4 is a diagram for explaining the operation of the piezoelectric vibrating piece according to the present embodiment. As shown in FIG. 4, a voltage is applied to the first and second excitation electrodes 42 and 44 of one vibration arm 18, and a voltage is applied to the first and second excitation electrodes 42 and 44 of the other vibration arm 18. Applied. Here, the first excitation electrode 42 of one vibrating arm 18 and the second excitation electrode 44 of the other vibrating arm 18 have the same potential (+ potential in the example of FIG. 4), and the second excitation electrode 18 of one vibrating arm 18 has the second potential. The first excitation electrode 42 and the second excitation electrode 44 are crossed so that the first excitation electrode 42 and the first excitation electrode 42 of the other vibrating arm 18 have the same potential (-potential in the example of FIG. 4). It is connected to an AC power supply by wiring, and an alternating voltage as a drive voltage is applied. An electric field is generated by the applied voltage as shown by an arrow in FIG. 4, whereby the vibrating arms 18 are excited so as to be in antiphase vibration with each other (the leading ends of the vibrating arms 18 approach and separate from each other). Bends and vibrates. The alternating voltage is adjusted so as to vibrate in the basic mode.

(Manufacturing method of the piezoelectric vibrating piece according to the first embodiment)
FIG. 5A to FIG. 6C are diagrams illustrating a method for manufacturing a piezoelectric vibrating piece according to the first embodiment of the present invention. In the present embodiment, a piezoelectric wafer 10 made of quartz or the like is used. The piezoelectric wafer 10 is a plate material having a parallel front surface 11 and a back surface 13 facing opposite to each other.

  As shown in FIG. 5A, the front surface 11 and the back surface 13 are partially covered with a wet etching resist 50, respectively. The wet etching resist 50 includes a patterned metal layer (for example, a Cr film and an Au film thereon) and a patterned resin layer on the metal layer. A metal layer is formed, a resin layer is formed with a photosensitive resin on the metal layer, the resin layer is patterned by photolithography, and etching using the patterned resin layer as a mask (whether dry or wet is acceptable) The metal layer is patterned. The region covered with the wet etching resist 50 includes a region for forming the first and second surfaces 12 and 14 of the vibrating arm 18 from a part of the front surface 11 and the back surface 13.

  As shown in FIG. 5B, the front surface 11 and the back surface 13 of the piezoelectric wafer 10 are fully etched by wet etching using the wet etching resist 50 as a mask. In the wet etching, the first and second side surfaces 32 and 34 connected to both sides of the vibrating arm 18 in the width direction of the first and second surfaces 12 and 14 are the first and second surfaces 12 and 14. To be substantially perpendicular to. Etching can be efficiently performed at low cost by wet etching. As a result, the base 16 and the pair of vibrating arms 18 extending from the base 16 are extracted. Even in the case of wet etching that depends on the crystal orientation, the first and second side surfaces 32 and 34 perpendicular to the front surface 11 and the back surface 13 can be formed depending on the etching time and etching conditions.

  As shown in FIG. 5C, the front surface 11 and the back surface 13 of the piezoelectric wafer 10 are partially covered with a dry etching resist 54, respectively. A Cr film may be used as the dry etching resist 54. The Cr film can be formed by electroless plating. The exposed area from the dry etching resist 54 includes an area for forming the groove 36 in the vibrating arm 18.

  As shown in FIG. 6A, half etching by dry etching is performed on the surface 11. Half etching can be performed more easily by dry etching than by wet etching. Dry etching is performed so that the groove 36 has the shape described above. The dry etching resist 54 is formed of Cr, and dry etching is performed with a reduced mask selection ratio (mask etching speed / etching speed of the piezoelectric wafer 10). As a result, the bottom surface 37 of the groove 36 can be a convex curved surface. In this way, the groove 36 is formed on the surface 11 of the vibrating arm 18. Although the dry etching does not depend on the crystal orientation, the inner surface of the groove 36 is inclined because the interval between the openings of the dry etching resist 54 is narrow. However, in the dry etching, unlike the wet etching, the inclined inner surfaces of the grooves 36 have a symmetrical shape. Note that half etching is performed on the front surface 11 with the dry etching resist 54 attached to the front surface 11 and the back surface 13 respectively.

  As shown in FIG. 6B, half etching by dry etching is also performed on the back surface 13. Thus, the grooves 36 are formed on the front surface 11 and the back surface 13 of the vibrating arm 18. The back surface 13 is half-etched with the dry etching resist 54 attached to the front surface 11 and the back surface 13 respectively.

  As shown in FIG. 6C, the dry etching resist 54 is removed. And as shown in FIGS. 1-3, the excitation electrode film | membrane 40 is formed.

According to the present embodiment, since the groove 36 is formed by dry etching, precise processing is possible. Since dry etching is performed after wet etching, all can be processed more precisely than by wet etching, and all can be performed more efficiently than by dry etching. Note that in this embodiment, since wet etching and dry etching are combined, the discharge of etching gas (for example, CF ₄ ) can be reduced by 20% compared to dry etching alone. In addition, the manufacturing method according to the present embodiment includes an obvious manufacturing process and a known process from the above-described configuration. Furthermore, a dry etching step may be added as necessary. For example, a process of forming a through hole (not shown) in the connection portion 28 by dry etching may be added.

(Method for Manufacturing Piezoelectric Vibrating Piece According to Second Embodiment)
FIG. 7A to FIG. 7D are diagrams illustrating a method for manufacturing a piezoelectric vibrating piece according to the second embodiment of the present invention. In this embodiment, instead of the process described with reference to FIG. 5C of the first embodiment, the process shown in FIG. 7A is performed. That is, a dry etching resist 54 is formed on the front surface 11, and a second protective film 56 is formed on the back surface 13 so as to cover it. The second protective film 56 may cover the entire back surface 13. However, since it is already after the steps shown in FIGS. 5A to 5B, the vibrating arm 18 and the base portion 16 are extracted.

  As shown in FIG. 7B, half etching is performed on the front surface 11 with the dry etching resist 54 attached to the front surface 11 and the second protective film 56 covering the back surface 13 (for example, the entire surface). . Thereby, the groove 36 is formed in the surface 11. Further, since the back surface 13 is covered with the second protective film 56, the back surface 13 is prevented from being etched, and the etching of the back surface 13 performed next enables the front surface 11 and the back surface 13 to be uniformly etched. ing. In addition, since the second protective film 56 covering the back surface 13 is larger than the dry etching resist 54 on the back surface 13 shown in FIG. 6A, the cooling effect is large and dry etching can be performed efficiently. Thereafter, the dry etching resist 54 on the front surface 11 and the second protective film 56 on the back surface 13 are removed.

  As shown in FIG. 7C, a dry etching resist 54 is formed on the back surface 13, and a first protective film 58 is formed on the front surface 11 so as to cover it. The first protective film 58 may cover the entire surface 11.

  As shown in FIG. 7D, half etching is performed on the back surface 13 with the dry etching resist 54 attached to the back surface 13 and the first protective film 58 covering the surface 11 and the groove 36 on the front surface 11 attached. To do. Thereby, a groove 36 is formed in the back surface 13. Further, since the front surface 11 is covered with the first protective film 58, the front surface 11 is prevented from being etched again, and the front surface 11 and the back surface 13 can be uniformly etched. Further, since the first protective film 58 covering the surface 11 and the groove 36 is larger than the dry etching resist 54 on the surface 11 shown in FIG. 6B, the cooling effect is large and the dry etching can be performed efficiently. it can. Thereafter, the dry etching resist 54 on the back surface 13 and the first protective film 58 on the front surface 11 are removed. About the other point, the manufacturing method demonstrated in 1st Embodiment mentioned above is applicable to the manufacturing method which concerns on this Embodiment. Also in this embodiment, the same effect as that of the first embodiment can be achieved.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same purposes and results). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

FIG. 1 is a plan view showing an embodiment of a piezoelectric vibrating piece according to the present invention. FIG. 2 is an enlarged cross-sectional view taken along the line II-II of the piezoelectric vibrating piece shown in FIG. 3 is an enlarged sectional view taken along line III-III of the piezoelectric vibrating piece shown in FIG. FIG. 4 is a diagram for explaining the operation of the piezoelectric vibrating piece according to the present embodiment. FIG. 5A to FIG. 5C are diagrams illustrating a method for manufacturing the piezoelectric vibrating piece according to the first embodiment of the present invention. 6A to 6C are views for explaining a method of manufacturing the piezoelectric vibrating piece according to the first embodiment of the invention. FIG. 7A to FIG. 7D are diagrams illustrating a method for manufacturing a piezoelectric vibrating piece according to the second embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS S1 ... Symmetrical surface, S2 ... Symmetrical surface, 10 ... Piezoelectric wafer, 11 ... Front surface, 12 ... First surface, 13 ... Back surface, 14 ... Second surface, 16 ... Base, 18 ... Vibrating arm, 22 ... Notch 24 ... 1st part, 26 ... 2nd part, 28 ... Connection part, 32 ... 1st side surface, 33 ... 1st inner surface, 34 ... 2nd side surface, 35 ... 2nd inner surface, 36 ... Groove, 37 ... bottom surface, 38 ... support arm, 39 ... third inner surface, 41 ... fourth inner surface, 40 ... excitation electrode film, 42 ... first excitation electrode, 44 ... second excitation electrode, 46 ... electrode 48 ... Connection electrode, 50 ... Wet etching resist, 54 ... Dry etching resist, 56 ... Second protective film, 58 ... First protective film

Claims (8)

The base,
A pair of vibrating arms extending from the base;
An excitation electrode film formed on each of the vibrating arms;
Including
Each of the vibrating arms includes first and second parallel surfaces facing opposite to each other, and first and second sides connected substantially vertically to both sides of the first and second surfaces. Have
A groove extending in the longitudinal direction of the vibrating arm is formed on each of the first and second surfaces,
The groove includes a first inner surface extending back to back with the first side surface, a second inner surface extending back to back with the second side surface, and a bottom surface between the first and second inner surfaces,
The first and second inner surfaces of the groove formed on the first surface are non-parallel to each other, pass through the center in the width direction of the first and second surfaces, and the first and second surfaces. 2 is symmetric with respect to a plane of symmetry perpendicular to the surface of
The piezoelectric vibrating piece, wherein the first and second inner surfaces of the groove formed on the second surface are non-parallel to each other and are symmetric with respect to the symmetry plane. The piezoelectric vibrating piece according to claim 1,
The bottom surface of the piezoelectric vibrating piece has a convex curved surface. In the piezoelectric vibrating piece according to claim 1 or 2,
The groove further includes third and fourth inner surfaces connecting both ends of the first and second inner surfaces,
The third and fourth inner surfaces of the groove formed on the first surface are non-parallel to each other, and are second symmetrical with respect to the symmetry plane and perpendicular to the first and second surfaces. It is plane symmetric about the plane,
The piezoelectric vibrating piece, wherein the third and fourth inner surfaces of the groove formed on the second surface are non-parallel to each other and are symmetric with respect to the second symmetry plane. In the piezoelectric vibrating piece according to claim 3,
The first inner surface of the groove formed on the first surface and the second inner surface of the groove formed on the second surface have the same angle with respect to the symmetry plane,
Piezoelectric vibration in which the second inner surface of the groove formed on the first surface and the first inner surface of the groove formed on the second surface have the same angle with respect to the symmetry plane Piece. (A) a step of performing full etching by wet etching by partially covering the parallel front and back surfaces of the piezoelectric wafer facing each other partially with a wet etching resist;
(B) after the step (a), partially covering the front surface and the back surface with a dry etching resist and performing half etching by dry etching;
Including
The region covered with the wet etching resist includes a region for forming the first and second surfaces of the vibrating arm from a part of the front surface and the back surface,
The exposed region from the dry etching resist includes a region for forming a groove in the vibrating arm,
In the step (a), the first and second side surfaces of the vibrating arm connected to both sides of the first and second surfaces in the width direction are substantially the same as the first and second surfaces. Perform the wet etching so that it is vertical,
In the step (b), the first and second inner surfaces of the groove extending back to back with the first and second side surfaces are not parallel to each other and pass through the center of the vibrating arm in the width direction. And the manufacturing method of the piezoelectric vibrating piece which performs the said dry etching so that it may become plane-symmetrical about the symmetry plane which cross | intersects the said 1st and 2nd surface perpendicularly | vertically. In the manufacturing method of the piezoelectric vibrating piece according to claim 5,
Forming the dry etching resist with Cr;
A method of manufacturing a piezoelectric vibrating piece, wherein the dry etching is performed so that a bottom surface of the groove has a convex curved surface. In the manufacturing method of the piezoelectric vibrating piece according to claim 5 or 6,
In the step (b), half etching is performed on the surface in a state where the dry etching resist is adhered to the front surface and the back surface, respectively, and then the dry etching resist is adhered to the front surface and the back surface, respectively. A method of manufacturing a piezoelectric vibrating piece by half-etching the back surface. In the manufacturing method of the piezoelectric vibrating piece according to claim 5 or 6,
The step (b)
In the state where the dry etching resist is attached to the front surface and the second protective film covering the back surface is attached, half etching is performed on the front surface, and then
Removing the dry etching resist on the front surface and the second protective film on the back surface;
In the state where the dry etching resist is attached to the back surface and the first protective film covering the groove on the surface and the surface is attached, half etching is performed on the back surface,
A method of manufacturing a piezoelectric vibrating piece, comprising removing the dry etching resist on the back surface and the first protective film on the front surface.

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