JP2019129351A - Piezoelectric vibration piece and piezoelectric vibrator, and manufacturing method - Google Patents

Abstract

To reduce unbalance in the thickness direction, in a piezoelectric vibration piece.SOLUTION: On the end faces of respective ends existing on both sides of a piezoelectric vibration piece 6 in a longitudinal direction, a step 46 having a first ramp 43, a second ramp 44, and a coupling part 45 is formed. The step 46 is formed by shifting the mask formation position in the first principal surface 41 and the second principal surface 42 in the longitudinal direction, while taking the cut angle of quartz into account, when forming the configuration of the piezoelectric vibration piece 6 by wet etching. By forming the step 46, unbalance in the thickness direction is restrained. As a result, a vibration arm part 7 of good balance can be formed, and a vibration piece excellent in vibration leakage characteristics and impact resistance can be manufactured. The step 46 is formed at least on the tip side end face (open end side end face) of the vibration arm part 7, and when formed on the end face (end face of the proximal region 8) on the opposite side to the vibration arm part 7, or on both end faces of the support arm part 9, overall unbalance is restrained furthermore.SELECTED DRAWING: Figure 1

Description

The present invention relates to a so-called tuning fork type piezoelectric vibrating reed and a piezoelectric vibrator using quartz crystal, and a manufacturing method.

For example, in electronic devices such as mobile phones and portable information terminals, a piezoelectric vibrator using a piezoelectric vibrating reed formed in a tuning fork shape as a device used as a time source, timing source such as control signal, reference signal source, etc. Used.
This tuning fork type piezoelectric vibrating piece includes a base, a pair of vibrating arms extending from the base, and a pair of vibrating arms extending from the base to both outer sides of the vibrating arms. A piezoelectric vibrating piece is known (see Patent Documents 1 and 2).

By the way, with the miniaturization of electronic devices in recent years, the demand for the miniaturization of the piezoelectric vibrator and the piezoelectric vibrating reed is further increasing.
As a method of obtaining a small piezoelectric vibrating piece, a method of wet etching a wafer is known.

FIG. 10 shows a side arm type piezoelectric vibrating piece 600. FIG. 10A shows a planar shape, and FIGS. 10B to 10E show cross sections of the manufacturing process of the fork and the support arm.
Form masks 501 and 502 (FIGS. 10B and 10D) corresponding to the outer shape of the piezoelectric vibrating piece on both sides of a wafer made of a piezoelectric material such as quartz, and immerse the masks in an etching solution. Then, the wafer portion (portion other than the masks 501 and 502) in contact with the etching solution is removed from the both surface side until it is gradually penetrated to form an outer shape. That is, the portions other than the masks 501 and 502 are penetrated and removed to form the outer shape of the piezoelectric vibrating reed.

However, when the piezoelectric vibrating reed is formed by wet etching, as shown in FIGS. 10A and 10C, the forks of the pair of vibrating arms 700 and the vibrating arms 700, the supporting arms 900 and the base 800 The deformed portion 770 is formed at the fork with the vibrating arm 700). The deformed portion 770 is formed as an etching residue due to the etching anisotropy of quartz crystal, and is formed in an inclined shape.
It is desirable that the sloped shaped portion 770 has a difference in the rigidity of the left and right vibrating arms 700 and 700 to deteriorate the vibration characteristics, and therefore be as small as possible.
Therefore, in the related art, the deformed portion 770 is reduced in size by immersing in the etching solution for a while after the portions other than the masks 501 and 502 are removed and penetrated by the etching solution.

JP 2004-357178 A JP 2005-102138 A

However, in order to make the deformed portion 770 small, it is inclined in the thickness direction at the end face in the length direction where the deformed portion 770 does not exist (the portion that is not the fork) by immersing it in the etching solution after the penetration. The inclined surface 431 is formed.
That is, the end surface of the base 800 shown on the left side of FIGS. 10C and 10E (the end surface opposite to the deformed portion 770), and the open end side of the support arm 900 and the vibrating arm 700 shown on the right side of FIG. At the end face, an inclined surface 431 inclined in the thickness direction is formed also by the etching anisotropy of the quartz.

In this case, the cross-sectional shapes of the vibrating arm portion 700 and the support arm portion 900 become unbalanced in the thickness direction, which causes vibration leakage and reduced impact resistance.
In particular, when the tuning fork type piezoelectric vibrating reed of quartz is further miniaturized, the angle (cut angle) with respect to the crystal axis at the time of cutting the quartz is increased in order to adjust the temperature characteristic (TP). It is common. However, since the inclination of the formed inclined surface 431 changes depending on the cut angle, when the cut angle is increased, the inclined surface 431 having a larger inclination is formed, resulting in a more unbalanced shape.

  Also, as shown in FIG. 10 (c), in the plurality of forks, the surface on the opposite side of the deformed portion 770 is formed obliquely, so that the width on one side of the main surface is narrowed to L1, and against vibration There is a problem that the strength decreases. Although it is possible to make the width L1 on the narrowed side of the fork part long enough to withstand vibration, the width of the main surface on the opposite side (the upper side of the drawing) increases, and the entire length of the piezoelectric vibrating piece Will become longer.

  It is an object of the present invention to suppress the occurrence of vibration leakage and a reduction in impact resistance in the piezoelectric vibration reed with less thickness imbalance in the cross-sectional shape in the length direction.

(1) In invention of Claim 1, a base part, a pair of vibrating arm part extended in parallel from the said base part, and the step part formed in the end surface of the at least open end side of the said vibrating arm part, The step portion is in a cross-sectional view parallel to the longitudinal direction of the vibrating arm portion and perpendicular to the width direction of the pair of vibrating arm portions, and the inner side in the thickness direction of the vibrating arm portion is closer to the inner side in the longitudinal direction. A first inclined portion that is inclined from one main surface so as to be positioned, a second inclined portion that is inclined from the other main surface so that the inner side in the thickness direction of the vibrating arm portion is positioned on the outer side in the longitudinal direction, There is provided a piezoelectric vibrating piece comprising: a connecting portion that connects a first inclined portion and the second inclined portion.
(2) In the invention described in claim 2, the step is formed on an end surface of the base opposite to the side on which the vibrating arm is extended. Provided is the piezoelectric vibrating reed described.
(3) In the invention described in claim 3, a support arm portion extending in parallel with the pair of vibrating arm portions from the base portion is provided, and the stepped portion is provided on an end surface on the open end side of the support arm portion. The piezoelectric vibrating reed according to claim 1 or claim 2, characterized in that it is formed.
(4) In the invention according to claim 4, the support arm is formed between a pair of support arms formed on both sides of the pair of vibrating arms, or between the pair of vibrating arms. The piezoelectric vibrating reed according to claim 3, wherein the piezoelectric vibrating reed is a single supporting single arm.
(5) The invention according to claim 5 includes the piezoelectric vibrating piece according to any one of claims 1 to 4 and a package that accommodates the piezoelectric vibrating piece. Provided is a piezoelectric vibrator characterized by the present invention.
(6) The invention according to claim 6 is a method for forming a tuning-fork type piezoelectric vibrating piece having at least a base and a pair of vibrating arms extending in parallel from the base, wherein the crystal is cut into a predetermined shape. A mask step of forming a mask having a shape corresponding to the outer shape of the piezoelectric vibrating reed on both main surfaces of the wafer cut out at an angle θ, and immersing the wafer on which the mask is formed in an etchant An outer surface forming step for forming an outer shape, and an electrode forming step for forming two systems of electrodes on the vibrating arm portion, wherein the mask step is performed on the main surface side where the angle with the optical axis of quartz becomes an obtuse angle A method of manufacturing a piezoelectric vibrating reed is characterized in that the mask of the portion corresponding to the vibrating arm portion is formed longer by the distance M than the main surface side which is an acute angle.
(7) In the invention according to claim 7, the distance M is in the range of 0 <M <2 × t × tan θ, where t is the thickness of the wafer. A method of manufacturing the piezoelectric vibrating reed according to
(8) In the invention according to claim 8, in the mask step, the mask corresponding to the base on the main surface side where the angle with the optical axis of the quartz crystal is obtuse is more than the main surface side which is the acute angle The method for manufacturing a piezoelectric vibrating reed according to claim 6 or 7, characterized in that it is formed longer by a distance M on the side opposite to the side on which the vibrating arm portion is formed.
(9) In the invention according to claim 9, the mask step has a shape corresponding to the outer shape of a piezoelectric vibrating reed having a support arm extending parallel to the pair of vibrating arms from the base. A method of manufacturing a piezoelectric vibrating reed according to claim 6, 7 or 8, characterized in that a mask of the following is formed.
(10) In the invention according to claim 10, a step of manufacturing a piezoelectric vibrating piece by each of the steps of claims 6 to 9, and the piezoelectric vibrating piece in a package A method for manufacturing a piezoelectric vibrator, comprising: a mounting step of mounting on a formed mounting portion; and a sealing step of sealing the package.

  According to the present invention, in a cross-sectional view that is parallel to the longitudinal direction of the vibrating arm portion and orthogonal to the width direction of the vibrating arm portion, the first inclined portion, the second inclined portion, at least on the end surface on the open end side of the vibrating arm portion, Since the step portion having the connecting portion is formed, the piezoelectric vibrating piece, the piezoelectric vibrator, and the like, which have less imbalance in the thickness direction and can suppress the occurrence of vibration leakage and the reduction in impact resistance, A manufacturing method can be provided.

It is the top view and sectional drawing which represented the external shape of the piezoelectric vibrating piece which concerns on embodiment. It is a comparison figure of this embodiment and conventional in the section of a piezo-electric oscillation piece. It is explanatory drawing showing the arrangement | positioning relationship of both the masks in both the main surfaces. It is an etching state explanatory view in an embodiment. It is sectional drawing of the mask arrangement | positioning of both the main surfaces in a fork part, and the edge part shape formed. It is sectional drawing of the 1st modification of the mask arrangement | positioning of both the main surfaces in a vibrating arm part and a support arm part, and the edge part shape formed. It is sectional drawing of the 2nd modification of the mask arrangement | positioning of both the main surfaces in a vibrating arm part and a support arm part, and the edge part shape formed. FIG. 7 is a plan view showing another shape of the piezoelectric vibrating reed. It is a disassembled perspective view of the piezoelectric vibrator in which the piezoelectric vibrating reed of this embodiment was mounted. It is an explanatory view showing the plane shape of the conventional piezoelectric vibrating piece, and the section of the manufacturing process of a fork part and a support arm.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 1 to 9.
(1) Outline of Embodiment This embodiment is directed to a tuning fork-type piezoelectric vibrating reed 6 in which a pair of vibrating arms 7 extend in the same direction in parallel from a base 8.
The end face of each end (except for the end of the fork) on both sides in the longitudinal direction of the piezoelectric vibrating reed 6 is directed from the first major surface 41 to the second major surface 42, such as a cut angle of quartz (for example, A slope of + 2 ° is formed. The piezoelectric vibrating reed 6 of the present embodiment has a first inclined portion 43, a second inclined portion 44, and a connecting portion 45 on each of the inclined surfaces formed from the first main surface 41 to the second main surface 42. The step 46 is formed.
When forming the outer shape of the piezoelectric vibrating reed 6 by wet etching, the stepped portion 46 takes the positions at which the mask is formed on the first main surface 41 and the second main surface 42 in the longitudinal direction, taking into consideration the cut angle of quartz. Form by shifting.
By forming the step 46, unbalance in the thickness direction is suppressed. As a result, a well-balanced vibrating arm portion 7 can be formed, and a vibrating reed excellent in vibration leakage characteristics and impact resistance can be manufactured.
The step 46 is formed at least on the end face (open end face) of the vibrating arm 7, but for mounting the piezoelectric vibrating reed 6 or the end face on the opposite side of the vibrating arm 7 (end face of the base 8) By forming on the both end surfaces of the formed support arms (the pair of support arms 9 and the support single arm 9 c), the overall imbalance is further suppressed.

(2) Details of the Embodiments Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the following embodiments, a so-called side arm type piezoelectric vibrator will be described as an example of the piezoelectric vibrating reed. In the drawings used for the following description, the scale of each member is appropriately changed in order to make each member have a recognizable size.

In the following description, an XYZ coordinate system is set, and the positional relationship of each member will be described with reference to this XYZ coordinate system. At this time, the direction perpendicular to the main surface of the piezoelectric vibrating reed (that is, the thickness direction of the piezoelectric vibrating reed) is "Z-axis direction", and the longitudinal direction of the vibrating arm (that is, the longitudinal direction of the piezoelectric vibrating reed) is "Y-axis The direction ”, the direction perpendicular to the Y-axis direction and the Z-axis direction (that is, the width direction of the piezoelectric vibrating piece) is defined as“ X-axis direction ”.
In addition, when the X axis, Y axis, and Z axis shown in the figure correspond to the electric axis, mechanical axis, and optical axis in the crystal, the X axis is the electric axis, and the X axis is rotated by the cut angle θ. The 'axis is a mechanical axis, and the Z' axis is an optical axis.

FIG. 1 shows a plane (a) representing the outer shape of the piezoelectric vibrating piece 6 in the present embodiment and a cross section (b) along the longitudinal direction.
In addition, since the piezoelectric vibrating reed 6 of this embodiment has a left-right symmetrical structure, both the symmetrically arranged portions are represented by the same numeral, such as the vibrating arm portion 7a and the vibrating arm portion 7b, and both A description will be given with distinguishing marks ab and AB. And when distinguishing mark is omitted suitably, it shall be pointing to each part. However, the distinction of a and b about step 46a and 46b is removed.
Further, in the following drawings, the scale is appropriately changed in order to make it possible to recognize the shapes and states of the respective members. In each cross-sectional view, a cross-sectional hatch is appropriately omitted for convenience.

In the present embodiment, among the piezoelectric vibrating reeds using quartz as a piezoelectric material, as shown in FIG. 1A, a so-called side arm type piezoelectric vibrating reed 6 will be described as an example.
The piezoelectric vibrating piece 6 includes a vibrating arm portion 7 (7a, 7b) extending in parallel from the base portion 8, and a supporting arm portion 9 (9a, 9b) extending from the base portion 8 in the same direction outside the vibrating arm portions 7. ing.

The pair of vibrating arm portions 7 are arranged to be parallel to each other, and vibrate with the end portion on the base portion 8 side as a fixed end and the tip end as a free end.
On the tip end side of the pair of vibrating arms 7, widening portions 71 (71a, 71b) formed to be wider on both sides than the substantially central portion of the entire length are provided. The widening portion 71 formed on the vibrating arm 7 has a function of increasing the weight of the vibrating arm 7 and the moment of inertia at the time of vibration. As a result, the vibrating arm portion 7 can easily vibrate, the length of the vibrating arm portion 7 can be shortened, and the size can be reduced.
A weight film for frequency adjustment is formed on the main surface of the widened portion 71. By performing laser trimming on the weight film, a part of the weight film is removed in accordance with the amount of frequency deviation to adjust the frequency. It is done.
In the piezoelectric vibrating piece 6 of the present embodiment, the widened portion 71 is formed in the vibrating arm portion 7, but the widened portion 71 is formed such that the width of the distal end portion of the vibrating arm portion 7 is substantially the same width as the central portion. It is also possible to use a piezoelectric vibrating piece (for example, see FIG.

Grooves 72 (72 a and 72 b) extending from the base 8 side to the front of the widening portion 71 are formed on both main surfaces of the vibrating arm 7. As a result, the cross-sectional shape of the vibrating arm 7 in the XZ plane is H-shaped.
On the outer surface (outer peripheral surface) of the pair of vibrating arm portions 7, both the outer side surfaces of the vibrating arm portion 7 a, the first system formed in the groove 72 b of the vibrating arm portion 7 b, and the outer side of the vibrating arm portion 7 b A pair of (two systems) excitation electrodes are formed (not shown in the figure), which are composed of the second system formed on the both side surfaces and the groove 72a of the vibrating arm section 7a.
Although not shown, a first mount electrode connected to the first system excitation electrode is formed from the base 8 to the outer surface (outer peripheral surface) of the support arm portion 9a, and is connected to the second system excitation electrode. A mount electrode is formed from the base 8 to the outer surface (outer peripheral surface) of the support arm 9 b.
The excitation electrode and the mount electrode are a laminated film including a first chromium (Cr) layer and a second gold (Au) layer, and are formed by electrode sputtering or the like.

An extension 81 (81a, 81b) extending outward from both end surfaces in the width direction of the piezoelectric vibrating reed 6 is connected to the base 8, and the support arm 9 is connected to an end of the extension 81. The pair of support arm portions 9a and 9b are disposed on both outer sides of the vibrating arm portions 7a and 7b.
The length of the support arm 9 in the present embodiment is formed to a length before the widening portion 71 of the vibrating arm 7, but in the case where it is the same as the vibrating arm 7 (including each width 71) When the length is longer than the vibrating arm portion 7 and the length to the periphery of the center of gravity of the piezoelectric vibrating piece 6 (same position as the center of gravity, slightly shorter, longer position), around the position of the half of the total length of the piezoelectric vibrating piece 6 It is formed to the length etc.
The support arm portion 9 is bonded to a mounting portion 14 formed on the piezoelectric vibrator 1 to be described later with a conductive adhesive 51 so that the entire piezoelectric vibrating reed 6 is fixed and supported at the bonding position of the support arm portion 9. Be done. In addition, the fixing point (adhesion point) of the supporting arm 9 is from the center to the end in the case of two places across the center in the case of the tip of the supporting arm 9 in the lengthwise direction and one place of the center. It is fixed in various ways, such as in the case of a single long region.

  The outer shape of the piezoelectric vibrating reed 6 of the present embodiment is also formed by wet etching. For this reason, similarly to the conventional piezoelectric vibrating piece described with reference to FIG. 10, the fork (the extension 81a portion) between the vibrating arm portion 7a and the supporting arm portion 9a, the vibrating arm portion 7a, and the vibrating arm portion 7b. Deformed portions 77 are formed at three locations, the fork portion and the fork portion (the portion of the extension portion 81b) between the vibrating arm portion 7b and the support arm portion 9b. The deformed portion 77 is formed to be as small as possible by adjusting the etching time (longer than the time until the portion other than the mask penetrates) as in the conventional case.

Next, the shape of the end in the longitudinal direction (Y direction) of each part of the piezoelectric vibrating reed 6 according to the present embodiment will be described with reference to FIG.
FIG. 1 (b) shows a cross section (cross section along the ZY plane) along a longitudinal line in the vibrating arm 7 and the support arm 9, and the longitudinal center line passing through the thickness center is J represents the vibrating arm 7 and the support arm 9 with the arm 40.
As shown in FIG. 1B, the end face on the tip end side (the side opposite to the base 8) of the arm 40 and the end face on the base 8 side extend from the first main surface 41 side to the second main surface 42 side. A step 46 is formed.
That is, the stepped portion 46 includes the following portions in a cross-sectional (ZY plane) view that is parallel to the longitudinal direction of the vibrating arm portion 7 and orthogonal to the width direction of the pair of vibrating arm portions 7.
(A) The 1st inclination part 43 which inclines in a front end side direction (+ Y direction) toward the centerline J direction (-Z direction) from the one 1st main surface 41 side.
(B) A second inclined portion 44 inclined from the other second main surface 42 toward the center line J direction (+ Z direction) in the direction toward the base 8 (−Y direction).
(C) A connecting portion 45 that connects the first inclined portion 43 and the second inclined portion 44.
In this way, when the cross section (ZY plane) is viewed, the step portion 46 including the first inclined portion 43, the second inclined portion 44, and the connecting portion 45 is formed on the end surface of the arm portion 40, so that the center line around the end surface is formed. From J, the unbalance between the first main surface 41 side and the second main surface 42 side is suppressed as compared with the conventional case.

FIG. 2 compares the end face (a) on which the stepped portion 46 is formed in the present embodiment with the cross-sectional (ZY plane) shape in the conventional end face (b).
In the cross section shown in FIG. 2, the center line J, the reference line Q in the Z direction orthogonal to the center line J at the end face, and the area of each region formed by the end face are a, b and c.
In this case, as shown in FIG. 2B, in the conventional piezoelectric vibrating piece, the second main surface is larger than the center line J by the area a on the first main surface 41 side than the cross-sectional area up to the reference line Q. On the 42 side, the area a is smaller. As a result, in the conventional piezoelectric vibrating reed, the difference of the cross-sectional area 2a exists between the first main surface 41 side and the second main surface 42 side.

On the other hand, as shown in FIG. 2A, in the piezoelectric vibrating reed 6 of the embodiment, the area on the first main surface 41 side is smaller than the cross-sectional area up to the reference line Q by the area b, and the area on the second main surface 42 side. b is more. As a result, in the piezoelectric vibrating reed 6 of the present embodiment, there is a difference in the cross-sectional area 2 b between the first main surface 41 and the second main surface 42.
Here, since the cross-sectional area b = a−c, the difference δ between the difference 2 b in the present embodiment and the conventional difference 2 a is δ = 2 a−2 b = 2 a−2 (a−c) = 2 c.
That is, the piezoelectric vibrating reed 6 of this embodiment is (in the vertical direction) on the first main surface 41 side and the second main surface 42 side from the center line J at the end surfaces of the vibrating arm 7 and the supporting arm 9. It can be seen that the imbalance is smaller by 2c in cross-sectional area than in the prior art.

FIG. 3 is a cross-sectional view showing an example of the arrangement of the masks 51 and 52 for forming the stepped portion 46 of FIG. 1B at both ends in a cross-sectional (ZY plane) view in the outer shape forming step.
As shown in FIG. 3, both ends in the Y-axis direction of the mask 51 formed on the first main surface 41 of the arm portion 40 are shifted by a distance M from the mask 52 formed on the second main surface 42 to the + Y-axis direction side. It is formed to be in the
In other words, the longitudinal ends of the mask corresponding to the arm portion 40 (the −Y side end portion and the + Y side (open end side end portion) of the arm portion 40) have an acute angle with the optical axis of the crystal. The mask on the main surface side at an obtuse angle (the mask 52 on the second main surface 42 on the −Y side and the mask 51 on the first main surface 41 on the + Y side) is longer in the longitudinal direction than the mask on the surface side. Form to be located.
As a result, the mask corresponding to the arm 40 on the main surface side at an obtuse angle with the optical axis of quartz (the mask 52 on the second main surface 42 on the -Y side, the first main surface 41 on the + Y side) The side mask 51) is formed longer than the acute major surface side by a distance M.

As shown in FIG. 3, the thickness of the wafer including the arm 40 is t, and the angle (hereinafter, cut angle) with respect to the crystal axis (machine axis Y ': represented by V in the figure) when cutting the piezoelectric plate from the wafer Assuming that θ, the distance M for shifting the mask 51 and the mask 52 satisfies the following conditional expression (1).
0 <M <2 × t × tan θ (1)

When M = 0, the design is the same as the existing design (conventional).
On the other hand, in the case of M ≧ 2 × t × tan θ, there is a possibility that the cross-sectional shape of the deformed portion 77 formed at the fork portion becomes an unbalanced shape in the thickness direction. On the other hand, according to the present embodiment, by satisfying the conditional expression (1), the cross-sectional shape in the thickness direction of the deformed portion 77 (see FIG. 1A) can be a well-balanced shape.

FIG. 4 is a sectional view (ZY plane) showing the progress of the wafer 50 on which the mask 51 and the mask 52 are formed by providing a shift of the distance M by the wet etching process. In FIG. 4, portions corresponding to the arms 40 (the vibrating arms 7 and the supporting arms 9) of the wafer 50 for forming the outer shape of the piezoelectric vibrating reed 6 are shown.
As a reference for making the progress of etching easy to understand, reference lines Q2 are provided at the positions of the end surfaces located on the center side of both end surfaces on the −Y side of the masks 51 and 52 and both end surfaces on the + Y side. Q3 is displayed. The reference lines Q2 and Q3 are imaginary lines perpendicular to the main surface and drawn to the end face in the longitudinal direction of the mask, at which the angle with the optical axis of the quartz crystal (inclined from the main surface by the cut angle θ) is acute.

As shown in FIG. 4A, a wafer 50 having masks 51 and 52 formed on both sides is immersed in an etching solution.
Thereby, the etching process can proceed simultaneously from both sides of the first main surface 41 and the second main surface 42 of the wafer 50. That is, the etching proceeds in the direction of the cut angle θ from the both sides of the wafer 50 due to the etching anisotropy of the quartz. That is, etching proceeds in the s1 and s2 directions from the end of the mask 51, and etching proceeds in the s3 and s4 directions from the end of the mask 52.

FIG. 4B shows a state immediately after the crystal is etched from both sides by the etching solution and penetrated.
In the state immediately after penetrating, the etching surface with the cut angle θ is displaced, so that a coupling surface 45p substantially parallel to 41 is formed on the main surface.
The connecting surface 45p is formed at a position shifted from the center in the width direction (Z direction). This formation position is on the side where the reference lines Q2, Q3 and the end of the mask coincide with each other. The end on the -Y (left) side is on the mask 51 side, and the end on the + Y (right) side is the mask 52. It is formed off the side.
This deviation is because the etching rate in the direction (s1, s3) in which the etching progress direction is an acute angle with respect to the reference lines Q2, Q3 is slower than the etching rate in the direction (s2, s4) in which the etching direction is obtuse. .

FIG. 4C shows a state after the etching is continued for a predetermined time after the penetration.
Etching in the direction of the inclination angle θ progresses with respect to the connecting surface 45p formed immediately after penetrating, but since the progress proceeds faster toward the outer side in the longitudinal direction, the connecting surface 45p gradually inclines. The etching speed that proceeds while being inclined with respect to the connecting surface 45p is defined as v1.
In addition, for the two inclined surfaces formed by the progress in the cut angle θ direction (s1 to s4), etching proceeds in the Y direction (this traveling speed is v2), and the inclined surface is the center in the longitudinal direction. Translate in the direction of The etching rate in these two directions is v2> v1.
Then, when the etching process is finished after a predetermined time has elapsed from the penetration, the step 46a including the first inclined portion 43a, the second inclined portion 44a, and the connecting portion 45a is the reference line Q2 on both end surfaces in the longitudinal direction. A step portion 46b is formed on the reference line Q3 side. The step portion 46b includes the first inclined portion 43b, the second inclined portion 44b, and the connecting portion 45b.

Note that the connecting surface 45p shown in FIG. 4B is similarly formed in the conventional case where the distance M = 0. However, since both the end faces of the mask 51 and the mask 52 are formed in Q2 and Q3, they are smaller than the present embodiment. For this reason, even after penetration by etching, the etching continues to be performed and the etching disappears, and as shown in FIG. 10E, no step is formed and only one inclined surface is formed.
After the etching process described above, the masks 51 and 52 are removed, thereby forming the outer shape of the piezoelectric vibrating reed 6 in which the step portions 46a and 46b are formed on both end surfaces in the longitudinal direction.

  As described above, in the etching process according to the present embodiment, the mask end portion (the mask 51 is the + Y side end portion and the mask 52 is the −Y side end portion) on the side that is easily etched in relation to the cut angle θ. Further, it extends to the outer side in the axial direction from the mask end portion (the mask 51 is the -Y side end portion and the mask 52 is the + Y side end portion) on the side where etching is difficult. Thus, the etching rates of the + Z-axis direction side portion and the −Z-axis direction side portion are adjusted so as to provide a good balance at both end surfaces of the wafer 50 in the Y direction.

Moreover, the continuation of the etching after penetrating by etching from both main surfaces ends with the connecting portions 45a and 45b remaining.
As described in FIG. 2, the end surfaces of the center line J formed on the first main surface 41 side and the second main surface 42 side are point-symmetric about the intersection of the center line J and the reference line Q. It is preferable to finish in the following condition.

After the outer shape forming step by the above etching process, an electrode forming step, a weight metal film forming step, a frequency adjustment step, and a singulation step are sequentially performed. Thereby, the piezoelectric vibrating piece 6 can be manufactured from the wafer 50.
However, the frequency adjustment process may not be performed in the manufacturing process of the piezoelectric vibrating reed 6, and the completed piezoelectric vibrating reed 6 may be mounted after being mounted on the mounting portion of the piezoelectric vibrator 1.

FIG. 5 is a cross-sectional view of the mask arrangement of both main surfaces at the forks and the shape of the end portion to be formed in the above-mentioned etching process.
At the fork, a deformed portion 77 is formed at the end in the + Y direction by etching (see FIG. 1A).
Therefore, as shown in FIG. 5A, the mask 51 on the first main surface 41 side and the mask 52 on the second main surface 42 side have the same position of the end on the + Y side and the −Y side. The end portion of the mask 52 is extended to the outside in the -Y direction, as in FIG. 4A.
Thus, after the etching process, as shown in FIG. 5 (b), the deformed portion 77 formed on the fork is formed small in a vertically balanced manner as in the prior art, and the deformed portion 77 is formed. The step 46a having the first inclined portion 43a, the second inclined portion 44a, and the connecting portion 45a is formed on the opposite side of the step as described with reference to FIG. 1 (b).

And as shown in FIG.4 (b), since the 2nd inclination part 44a is formed in the axial direction outer side (-Y side) rather than the 1st inclination part 43a, length L2 by the side of the 2nd main surface 42 is shown. Can be made longer than the conventional length L1 (see FIG. 10 (c)).
Thereby, it is possible to suppress the strength against vibration at the fork portion from decreasing or the length of the piezoelectric vibrating piece 6 from being increased.

Next, modifications of the shape of both end surfaces in the Y direction of the arm 40 (the vibrating arm 7 and the support arm 9) will be described.
In the described embodiment, the case where the step portions 46a and 46b are formed on both end surfaces has been described, but in this modification, the step portion is formed on one of the end portions.
FIG. 6 is a cross-sectional view of a first modification of the mask arrangement of both main surfaces 41 and 42 of the arm 40 and the shape of the end to be formed.
As shown in FIG. 6A, in the first modification, the mask 51 on the first major surface 41 side and the mask 52 on the second major surface 42 side are positioned at the same position as the end of the −Y side. At the end on the + Y side, as in FIG. 4A, the end on the mask 51 side is extended outward in the + Y direction.
As a result, as shown in FIG. 6B, in the arm 40, the step 46b is formed on the end surface on the + Y side, and the same inclined surface 431 as in the prior art is formed on the end surface on the -Y side. The inclined surface 431 is obtained by extending the first inclined surface 43 a to the second main surface 42.
According to the first modification, the entire end surface on the −Y side of the base 8 and the extension 81 including the fork becomes the inclined surface 431.
The arm portion 40 that is the target of the first modification is both the vibrating arm portion 7 and the support arm portion 9.

FIG. 7 shows the mask arrangement of both main surfaces 41 and 42 and the end shape to be formed in the second modification.
As shown in FIG. 7A, in the second modification, contrary to the first modification, the mask 51 on the first main surface 41 side and the mask 52 on the second main surface 42 side are the ends on the + Y side. The positions of the parts are the same, and at the end on the -Y side, the end on the mask 52 side is extended outward in the -Y direction.
As a result, as shown in FIG. 7B, in the arm 40, the step 46a is formed on the end face on the -Y side, and on the end face on the + Y side, one inclined surface 431 similar to the conventional one is formed. The inclined surface 431 is obtained by extending the first inclined surface 43 b to the first main surface 41.
According to the second modification, as in the embodiment, the stepped portion 46a is formed on the entire end surface on the -Y side of the base 8 and the extension 81 including the fork.

The arm part 40 that is the target of the second modification is the support arm part 9. That is, also in the second modified example, as described in the embodiment, in the vibrating arm portion 7, the step 46a and the step 46b are formed on both end surfaces in the Y direction.
The support arm portion 9 is fixed to the mounting portion 14 of the package 2 by the conductive adhesive 29 as described later, so even when the open end (end surface on the + Y side) side of the support arm portion 9 is the inclined surface 431, the piezoelectric vibrating reed This is because the influence on the vibration of 6 is small.
On the other hand, in the case of the vibrating arm 7, the open end (the end face on the + Y side) is a portion that vibrates largely due to excitation and is the portion where the effect of balance adjustment is the largest. It is like that.

In the embodiment and the modification described above, the configuration of the so-called side arm type piezoelectric vibrating reed 6 has been described, but in the case of a tuning fork type, the stepped portion 46 is provided at the longitudinal end of another type of piezoelectric vibrating reed It is also possible to form.
FIG. 8 is a plan view showing another shape of the piezoelectric vibrating reed, in which (a) shows a cantilever type piezoelectric vibrating reed 61 and (b) shows a center arm type piezoelectric vibrating reed 62.
In the cantilever-type piezoelectric vibrating reed 61 shown in FIG. 8A, vibrating arms 7a and 7b extending in parallel in the longitudinal direction from the base 8 are formed, and no supporting arm is present.
On the other hand, in the piezoelectric vibrating piece 62 shown in FIG. 8B, a supporting single arm portion 9c is formed between the vibrating arm portions 7a and 7b extending in parallel with the longitudinal direction from the base portion 8.
Also in the piezoelectric vibrating reeds 61 and 62, as in the embodiment and the modified example described above, at least one of the end surfaces in the Y direction of the arm (the vibrating arm 7 and the supporting single arm 9c) has a step 46a, By forming the stepped portion 46b, it is possible to form the piezoelectric vibrating reeds 61 and 62 having a good balance in the thickness direction.

Heretofore, the piezoelectric vibrating reeds 6, 61, 62 in which the stepped portion 46 is formed on the end surface in the Y direction of the piezoelectric vibrating reed in the present embodiment and the modification have been described.
Next, the case where the piezoelectric vibrating piece 6 is accommodated will be described as an example of the piezoelectric vibrator 1 that accommodates the piezoelectric vibrating pieces 6, 61, 62 formed as described above.
FIG. 9 is an exploded perspective view of the piezoelectric vibrator 1 accommodating the piezoelectric vibrating reed.
As shown in FIG. 9, the piezoelectric vibrator 1 of the present embodiment is a ceramic package including a package 2 having a cavity C hermetically sealed therein and a piezoelectric vibrating reed 6 housed in the cavity C. It is considered to be a surface mounted oscillator of the type.
The package 2 is formed in a substantially rectangular parallelepiped shape, and includes a package body 3 and a sealing plate 4 that forms a cavity C between the package body 3 by being joined to the package body 3.
The package body 3 includes a first base substrate 10 and a second base substrate 11 joined in a state of being superimposed on each other, and a seal ring 12 joined onto the second base substrate 11.

The upper surface of the first base substrate 10 corresponds to the bottom surface of the cavity C.
The second base substrate 11 is superimposed on the first base substrate 10 and is bonded to the first base substrate 10 by sintering or the like. That is, the second base substrate 11 is integrated with the first base substrate 10.
A connection electrode (not shown) is formed between the first base substrate 10 and the second base substrate 11 in a state of being sandwiched between the two base substrates 10 and 11.

The second base substrate 11 is provided with a through portion 11 a that constitutes a part of the side wall of the cavity C.
Inward projecting mounting portions 14A and 14B are provided on the inner side surfaces of both sides facing each other in the short direction of the penetrating portion 11a.
A pair of electrode pads (electrode portions) 20A and 20B, which are connection electrodes to the piezoelectric vibrating reed 6, are formed on the top surfaces of the mounting portions 14A and 14B. 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 of the package 2. The electrode pads 20A and 20B and the external electrodes 21A and 21B are, for example, a single-layer film of a single metal formed by evaporation, sputtering or the like, or a laminated film in which different metals are stacked.
The electrode pads 20A and 20B and the external electrodes 21A and 21B are second through electrodes (not shown) formed on the mounting portions 14A and 14B of the second base substrate 11, the first base substrate 10 and the second base substrate 11 And the first through electrode (not shown) formed in the first base substrate 10, respectively.
On the other hand, the conductive adhesive 29 is applied on the electrode pads 20A and 20B, and is bonded to the mount electrodes of the support arms 9a and 9b.

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

  The sealing plate 4 is a conductive substrate stacked on the seal ring 12, and is hermetically bonded to the package body 3 by bonding to the seal ring 12. A space defined by the sealing plate 4, the seal ring 12, the penetrating portion 11 a of the second base substrate 11, and the upper surface of the first base substrate 10 functions as a hermetically sealed cavity C.

The piezoelectric vibrator 1 shown in FIG. 1 is formed by the following steps.
(A) In the piezoelectric vibrating reed manufacturing process, the piezoelectric vibrating reed 6 of the stepped portions 46a and 46b is manufactured on the end surface in the Y direction according to the embodiment and modification described (see the description of FIG. 4).
(B) In the mounting step, the manufactured piezoelectric vibrating reed 6 is mounted on the electrode pad 20 of the mounting portion 14 formed on the package main body 3 by adhering the supporting arm 9 with the conductive adhesive 29.
(C) In the sealing step, the package plate 3 on which the piezoelectric vibrating reed 6 is mounted is sealed by the sealing plate 4.

As described above, according to the piezoelectric vibrating reed and the piezoelectric vibrator of the present embodiment, the stepped portions 46a and 46b are formed on the end surfaces of the vibrating arm 7 and the supporting arm 9 in the longitudinal direction, so that the thickness can be obtained. The imbalance of the shape in the direction is suppressed, and vibration leakage and impact resistance deterioration can be suppressed.
In addition, since the stepped portion 46a can be formed on the entire end surface of the base 8 and the extension portion 81 on the -Y side including the fork portion and the width L2> L1, it is possible to suppress a reduction in vibration resistance at the fork portion. Can.

DESCRIPTION OF SYMBOLS 1 Piezoelectric vibrator 2 Package 40 Arm part (vibration arm part, support arm part)
41 1st main surface 42 2nd main surface 43 1st inclination part 44 2nd inclination part 45 Connection part 46 Step part 51, 52 Mask 6, 61, 62 Piezoelectric vibration piece 7 Vibration arm part 8 Base part 81 Extension part 9 Support arm Section θ cut angle

Claims (10)

The base,
A pair of vibrating arms extending in parallel from the base;
A step portion formed on an end face on at least the open end side of the vibrating arm portion,
The stepped portion is positioned inward in the longitudinal direction toward the inner side in the thickness direction of the vibrating arm portion in a cross-sectional view parallel to the longitudinal direction of the vibrating arm portion and perpendicular to the width direction of the pair of vibrating arm portions. A first inclined portion that is inclined from one main surface; a second inclined portion that is inclined from the other main surface so that the inner side in the thickness direction of the vibrating arm portion is located on the outer side in the longitudinal direction; and the first inclined portion A connecting portion connecting the second inclined portion and the second inclined portion;
A piezoelectric vibrating reed characterized by comprising: The step portion is formed on the end surface of the base opposite to the side on which the vibrating arm portion extends.
The piezoelectric vibrating reed according to claim 1, wherein A support arm portion extending in parallel with the pair of vibrating arm portions from the base portion,
The stepped portion is formed on an end face on the open end side of the support arm,
The piezoelectric vibrating piece according to claim 1, wherein the piezoelectric vibrating piece is characterized in that The support arm is a pair of support arms formed on both outer sides of the pair of vibrating arms, or a single supporting arm formed between the pair of vibrating arms.
The piezoelectric vibrating reed according to claim 3, wherein A piezoelectric vibrating reed according to any one of claims 1 to 4;
A package for housing the piezoelectric vibrating reed;
A piezoelectric vibrator comprising: A method for forming a tuning-fork type piezoelectric vibrating piece having at least a base and a pair of vibrating arms extending in parallel from the base,
A mask step of forming a mask having a shape corresponding to the outer shape of the piezoelectric vibrating piece on both main surfaces of the wafer obtained by cutting the crystal at a predetermined cut angle θ;
An outer shape forming step of forming the outer shape of the piezoelectric vibrating reed by immersing the wafer on which the mask is formed in an etching solution;
An electrode forming step of forming two systems of electrodes on the vibrating arm portion,
In the mask process, a mask corresponding to the vibrating arm portion on the main surface side where the angle with the optical axis of the crystal is an obtuse angle is formed longer than the main surface side which is an acute angle by a distance M.
A method of manufacturing a piezoelectric vibrating reed characterized in that. The distance M is in the range of 0 <M <2 × t × tan θ, where t is the thickness of the wafer.
The method of manufacturing a piezoelectric vibrating piece according to claim 6. In the mask process, the mask corresponding to the base on the main surface side at an obtuse angle with the optical axis of quartz is opposite to the side on which the vibrating arm is formed than the main surface side at an acute angle To make the distance M longer,
A method of manufacturing a piezoelectric vibrating reed according to claim 6 or 7, characterized in that The mask process forms a mask having a shape corresponding to the outer shape of the piezoelectric vibrating piece having a support arm portion extending in parallel with the pair of vibrating arm portions from the base portion.
The method for manufacturing a piezoelectric vibrating piece according to claim 6, 7, or 8. A process of manufacturing a piezoelectric vibrating reed according to each process of any one of claims 6 to 9;
A mounting step of mounting the piezoelectric vibrating piece on a mounting portion formed in a package;
A sealing step of sealing the package;
A manufacturing method of a piezoelectric vibrator characterized by having.

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