CN113364426A

CN113364426A - Piezoelectric wafer, method for manufacturing piezoelectric wafer, and method for manufacturing piezoelectric vibrating reed

Info

Publication number: CN113364426A
Application number: CN202110244476.XA
Authority: CN
Inventors: 市村直也
Original assignee: SII Crystal Technology Inc
Current assignee: SII Crystal Technology Inc
Priority date: 2020-03-06
Filing date: 2021-03-05
Publication date: 2021-09-07
Also published as: JP7454962B2; JP2021141484A

Abstract

The invention relates to a piezoelectric wafer, a method for manufacturing the piezoelectric wafer and a method for manufacturing a piezoelectric vibrating reed, which can manufacture the piezoelectric wafer and the piezoelectric vibrating reed with less steps. The piezoelectric wafer (1) is provided with a plurality of frame sections (2), and a plurality of piezoelectric vibrating pieces (3) are coupled to each frame section (2) by a coupling section (21). The first excitation electrode (91) and the first electrode pad (23) of the piezoelectric vibrating reed (3), and the second excitation electrode (92) and the second electrode pad (24) are formed on the piezoelectric vibrating reed (3) and the frame (2) as electrodes divided into two systems. In the embodiment, the frame part (2) is provided with the protruding residue forming part (4), and the inclined surface parts (41, 42) for etching residues are formed between the side surface of the residue forming part (4) and the side surface of the frame part (2), so that the electrode pads (the first electrode pad (23) and the second electrode pad (24)) of the adjacent piezoelectric vibrating pieces (3) in the frame part (2) can be divided only by main surface exposure, and the inclined exposure process can be reduced.

Description

Piezoelectric wafer, method for manufacturing piezoelectric wafer, and method for manufacturing piezoelectric vibrating reed

Technical Field

The present invention relates to a piezoelectric wafer, a method of manufacturing the piezoelectric wafer, and a method of manufacturing a piezoelectric vibrating reed, and more particularly to a piezoelectric wafer in which a plurality of piezoelectric vibrating reeds are formed.

Background

For example, in electronic devices such as mobile phones and portable information terminals, piezoelectric vibrators having a piezoelectric vibrating reed made of quartz crystal or the like mounted therein are widely used as devices for time sources, timing sources such as control signals, reference signal sources, and the like. The piezoelectric vibrating reed is used by picking up a small piece of piezoelectric vibrating reed from each of piezoelectric wafers having a large area and a plurality of piezoelectric vibrating reeds formed on the piezoelectric wafer. The piezoelectric wafer uses a large-area wafer, is thinned to the thickness of the piezoelectric vibrating piece by lapping, polishing, or the like, and then, by transcription, etching, or the like based on a photolithography technique, a plurality of chip patterns of the piezoelectric vibrating piece connected to the frame portion on the wafer by the connection portions are formed.

However, since the piezoelectric resonator element is also reduced in size and thickness with the miniaturization of the piezoelectric resonator in recent years, it is difficult to directly perform contact detection on the piezoelectric resonator element for frequency measurement on a wafer, and therefore, electrode pads are arranged on a frame portion of the wafer from a pair of excitation electrode wiring patterns formed on the piezoelectric resonator element. Each piezoelectric vibrating piece is frequency-measured by pressing a probe or the like against a corresponding electrode pad or the like. Thereafter, the piezoelectric vibrating piece is cut at the connection portion to be singulated.

Further, when the piezoelectric vibrating reeds are arranged from a pair of excitation electrode wiring electrodes formed on the respective piezoelectric vibrating reeds to a pair of electrode pads formed on the frame portion, the pair of electrode pads and the wiring electrodes also need to be divided. The division of the pair of electrode pads facing one piezoelectric vibrating reed can be performed on the main surface of the frame portion, but the electrode pads between the adjacent piezoelectric vibrating reeds need to be divided on the side surfaces in addition to the main surface. Therefore, in addition to the exposure for dividing the electrode pad on the main surface, the exposure is required to be performed from an oblique direction on the side surface of the frame in order to divide the pad electrode on the side surface, and the oblique exposure increases the number of steps.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 4784700.

Disclosure of Invention

Problems to be solved by the invention

The invention aims to manufacture a piezoelectric wafer and a piezoelectric vibrating reed by fewer processes.

Means for solving the problems

(1) In the invention described in claim 1, there is provided a piezoelectric wafer including: a frame portion; a plurality of piezoelectric vibrating reeds having vibrating arm portions connected to each other in parallel in the frame portion; a first excitation electrode and a second excitation electrode formed on the respective piezoelectric vibrating pieces to vibrate the vibrating arm portion; a first electrode pad formed on the frame portion corresponding to each of the piezoelectric vibrating pieces and electrically connected to the first excitation electrode; a second electrode pad electrically connected to the second excitation electrode; a residue forming portion formed between adjacent connecting portions connecting the piezoelectric vibrating reed to the frame portion; and an inclined surface formed as a residue by the residue forming portion; the first electrode pad formed corresponding to one of the two adjacent piezoelectric vibrating reeds and the second electrode pad formed corresponding to the other piezoelectric vibrating reed are divided into the inclined surface formed as the residue on the main surface of the frame portion.

(2) In the invention described in claim 2, there is provided the piezoelectric wafer according to claim 1, wherein the residue formation portion is formed in a convex shape with respect to the frame portion in a direction in which the piezoelectric vibrating reed is formed, and the inclined surface is formed between the frame portion and both side surfaces of the convex residue formation portion.

(3) In the invention described in claim 3, there is provided the piezoelectric wafer according to claim 1, wherein the residue formation portion is formed in a concave shape recessed in a direction opposite to a direction in which the piezoelectric vibrating reed is formed with respect to the frame portion, and the inclined surfaces are formed on both side surfaces and a bottom surface of the concave shape.

(4) The invention described in claim 4 provides a method for manufacturing a piezoelectric wafer according to claim 1, claim 2, or claim 3, wherein the method for manufacturing a piezoelectric wafer includes: a preparation step of preparing a wafer; a profile forming step of forming the profile of the piezoelectric wafer from the prepared wafer; an electrode forming step of forming two systems of electrodes, i.e., a first system of the first excitation electrode and the first electrode pad and a second system of the second excitation electrode and the second electrode pad, by photolithography of the metal material after forming the metal material on the surface of the wafer having the formed outer shape; and a frequency adjustment step of applying a drive voltage from the first electrode pad and the second electrode pad to adjust the frequency of each of the piezoelectric vibrating pieces; in the electrode forming step, the metal material is divided into the first system and the second system by exposing the metal material from the main surface side using an electrode mask having an electrode pattern shape corresponding to the two systems of electrodes.

(5) In the invention described in claim 5, there is provided a method of manufacturing a piezoelectric vibrating reed, including: the method for manufacturing a piezoelectric wafer according to claim 4; and a singulation step of cutting the piezoelectric vibrating reeds connected in parallel to the frame portion from the manufactured piezoelectric wafer.

Effects of the invention

According to the invention of the present application, the first electrode pad formed corresponding to one of the two adjacent piezoelectric vibrating reeds and the second electrode pad formed corresponding to the other piezoelectric vibrating reed are divided into the inclined surface formed as the residue and the main surface of the frame portion, and therefore the piezoelectric wafer and the piezoelectric vibrating reed can be manufactured in fewer processes.

Drawings

Fig. 1 is an explanatory diagram showing a structure of a piezoelectric wafer in the first embodiment.

Fig. 2 is an enlarged view showing the periphery of the piezoelectric vibrating reed in the first embodiment.

Fig. 3 is an enlarged view showing a residue formation part and an inclined surface based on the residue in the first embodiment.

Fig. 4 is a flowchart showing a manufacturing process of the piezoelectric wafer in the first embodiment.

Fig. 5 is an enlarged view showing the periphery of the piezoelectric vibrating piece of the piezoelectric wafer in the second embodiment.

Fig. 6 is an explanatory view showing a modification of the piezoelectric wafer.

Detailed Description

Hereinafter, preferred embodiments of the piezoelectric wafer, the method for manufacturing the piezoelectric wafer, and the method for manufacturing the piezoelectric vibrating reed according to the present invention will be described in detail with reference to fig. 1 to 6.

(1) Brief description of the embodiments

The piezoelectric wafer 1 of the present embodiment includes a plurality of frame portions 2, and a plurality of piezoelectric vibrating reeds 3 are coupled to the respective frame portions 2 by a coupling portion 21. In the piezoelectric vibrating reed 3 and the frame portion 2, the first excitation electrode 91 and the first electrode pad 23 of the piezoelectric vibrating reed 3, and the second excitation electrode 92 and the second electrode pad 24 are formed as electrodes divided into two systems.

In the present embodiment, the frame portion 2 is provided with the residue forming portion 4 having a convex shape, and the

inclined surfaces

41 and 42 of the etching residue are formed between the side surface of the residue forming portion 4 and the side surface of the frame portion 2, so that the division between the electrode pads (the first electrode pad 23 and the second electrode pad 24) of the adjacent piezoelectric vibrating pieces 3 in the frame portion 2 can be performed only by the exposure of the main surface, and the inclined exposure process can be reduced.

The residue forming part 5 may be a concave shape in addition to the convex shape of the residue forming part 4. In this case, the inclined surfaces 51 to 53 are formed inside the concave shape, and the electrode pads are divided by exposing the main surfaces of the inclined surfaces 51 to 53.

(2) Details of the implementation.

Fig. 1 shows a part of the structure of a piezoelectric wafer 1 according to a first embodiment. Fig. 2 is an enlarged view showing the periphery of the piezoelectric vibrating reed 3. In the drawings of the present embodiment, hidden lines are indicated by broken lines, and broken portions are indicated by chain dotted lines.

As shown in fig. 1, a piezoelectric wafer 1 according to the first embodiment includes a plurality of frame portions 2 extending in the X direction, and two frame portions 2 extending in the Y direction formed at both ends in the X direction. The plurality of frame portions 2 extending in the X direction are arranged side by side at equal intervals in the Y direction, and both end sides thereof are connected to the frame portions 2 extending in the Y direction.

In fig. 1, the piezoelectric wafer 1 is shown as a square, but the outer edge side of the piezoelectric wafer 1 has a shape that follows the shape of the wafer before processing. The piezoelectric wafer 1 is made of a piezoelectric material such as quartz, lithium tantalate, or lithium niobate, and quartz is used in the present embodiment. Hereinafter, the frame portion 2 will be referred to as a frame extending in the X direction, and the description will be given.

As shown in fig. 2, the plurality of piezoelectric vibrating pieces 3 whose longitudinal direction is the Y direction are coupled to the respective frame portions 2 by the coupling portions 21 functioning as the connecting portions. The frame portions 2 are provided with first electrode pads 23 and second electrode pads 24 for the piezoelectric vibrating reeds 3 in parallel. That is, the first electrode pads 23 and the second electrode pads 24 are alternately formed in the frame portions 2 in parallel in the X direction. In each frame portion 2, a residue forming portion 4 for dividing an electrode is formed on a side surface of the frame portion 2 between two adjacent piezoelectric vibrating reeds 3. The residue forming part 4 is formed between the second electrode pad 24 of one piezoelectric vibrating reed 3 and the first electrode pad 23 of the other piezoelectric vibrating reed 3.

The piezoelectric vibrating reed 3 includes a pair of vibrating

arm portions

7a and 7b, a base portion 8, and a pair of

support arm portions

9a and 9 b. The coupling portion 21 is coupled to a side of the base 8 facing the frame portion 2, and a pair of vibrating

arm portions

7a, 7b are provided extending in a side-by-side state on a surface on the opposite side to the coupling portion 21 in the longitudinal direction (Y direction). The base 8 is provided with

support arms

9a and 9b for mounting the monolithic piezoelectric resonator element 3 in the case of the piezoelectric resonator. The pair of

support arm portions

9a and 9b extend in the width direction (X direction) of the piezoelectric vibrating reed 3 from the side surface on the coupling portion 21 side of the base portion 8, then bend in a direction away from the frame portion 2, and extend so as to be arranged in parallel to both outer sides of the vibrating

arm portions

7a and 7 b.

The pair of vibrating

arm portions

7a and 7b are arranged in parallel to each other, and vibrate with the end portion on the base 8 side being a fixed end and the tip end being a free end. When the width of the substantially central portion of the entire length of the pair of

vibration arm portions

7a and 7b is set to a standard width, the pair of

vibration arm portions

7a and 7b includes widened

portions

71a and 71b formed so as to be wider on both sides than the standard width. The widened

portions

71a and 71b have a function of increasing the weight of the

vibration arm portions

7a and 7b and the moment of inertia during vibration. This makes the vibrating

arm portions

7a and 7b easy to vibrate, and the length of the vibrating

arm portions

7a and 7b can be shortened, thereby achieving downsizing. In the piezoelectric vibrating reed 3 according to each of the embodiments and the modified examples, the widened

portions

71a and 71b are formed in the vibrating

arm portions

7a and 7b, but a piezoelectric vibrating reed without a widened portion may be used.

In the piezoelectric wafer 1 of the present embodiment, although not shown, weight metal films (composed of a coarse adjustment film and a fine adjustment film) for adjusting the vibration state (frequency adjustment) to vibrate in a predetermined frequency range are formed at the tip portions (widened

portions

71a and 71b) of the vibrating

arm portions

7a and 7 b. By removing only an appropriate amount of the weight metal film by, for example, laser irradiation, frequency adjustment is performed, and the frequency of the pair of vibrating

arm portions

7a and 7b can be controlled within the range of the rated frequency of the apparatus. The weight metal film may not be formed in the same manner as the widened portion.

Fig. 2(b) is a sectional view of a section taken along the line V1-V1 shown in fig. 2(a) as viewed in the direction of the arrow. As shown in fig. 2(a) and (b),

grooves

72a and 72b having a constant width in the longitudinal direction are formed in the pair of vibrating

arms

7a and 7 b. The

grooves

72a and 72b are formed so as to be recessed in the Z direction on both main surfaces (front and back surfaces) of the pair of vibrating

arm portions

7a and 7 b. The

groove portions

72a, 72b are formed from the base ends of the vibrating

arm portions

7a, 7b (the surface of the base portion 8 on the opposite side from the coupling portion 21) to the front of the widened

portions

71a, 71 b. By forming the

grooves

72a and 72b on both main surfaces, the end surfaces of the pair of vibrating

arm portions

7a and 7b are H-shaped. In the piezoelectric vibrating reed 3 of the piezoelectric wafer 1 according to each of the embodiments and the modified examples, the

grooves

72a and 72b are formed, but a piezoelectric vibrating reed without grooves may be used.

As shown in fig. 2(a) and (b), two excitation electrodes (a first excitation electrode 91 and a second excitation electrode 92) are formed on the main surface of the base 8 and the outer surfaces (outer circumferential surfaces) of the pair of vibrating

arm portions

7a and 7 b. The first excitation electrode 91 and the second excitation electrode 92 are electrodes that vibrate the pair of vibrating

arm portions

7a and 7b at a predetermined resonance frequency in a direction approaching or separating from each other when a voltage is applied thereto, and are patterned in an electrically disconnected state on the vibrating

arm portions

7a and 7 b. Specifically, the first excitation electrodes 91 are formed mainly on both side surfaces of one vibrating arm portion 7a and in both groove portions 72b of the other vibrating arm portion 7b in a mutually electrically connected state. In addition, the second excitation electrodes 92 are formed in a state of being electrically connected to each other mainly in the two groove portions 72a of the one vibrating arm portion 7a and on the two side surfaces of the other vibrating arm portion 7 b.

Although not shown, a mount electrode is formed on the main surface side of one of the

support arm portions

9a and 9b of the piezoelectric vibrating reed 3 as a mounting portion when the piezoelectric vibrating reed 3 is mounted on the case. The mount electrode of the support arm portion 9a is connected to the first excitation electrode 91 of the base portion 8, and further, to the first electrode pad 23. The mount electrode of the support arm portion 9b is connected to the second excitation electrode 92 of the base portion 8, and further, to the second electrode pad 24. The two systems of the first excitation electrode 91 and the second excitation electrode 92 are applied with a voltage via the first electrode pad 23 and the second electrode pad 24 in a manufacturing stage before the piezoelectric vibrating reed 3 is singulated, and are applied with a voltage via the pair of mount electrodes after the singulation.

In the present embodiment, the electrodes (the first excitation electrode 91, the second excitation electrode 92, the mount electrode, the wiring electrode, the first electrode pad 23, and the second electrode pad 24) are, for example, a laminated film of chromium (Cr) and gold (Au), and a thin film of gold is formed on the surface after the quartz and the chromium film having good adhesion are formed as a base film. However, the present invention is not limited to this case, and for example, a thin gold film may be further laminated on the surface of the laminated film of chromium and nickel-chromium alloy (NiCr), or a single-layer film of chromium, nickel, aluminum (Al), titanium (Ti), or the like may be formed.

Details of the formation of these various electrodes are set forth later, and are performed in the same manner as before. That is, the electrode material is formed on the entire piezoelectric vibrating reed 3 including the

grooves

72a and 72b before the electrodes are formed by vapor deposition or sputtering. Then, various electrode portions are left, and portions other than the electrodes are removed in a photolithography process, thereby forming two systems of electrode lines.

Fig. 3 is an enlarged view showing details of the residue forming part 4, and (a) shows a plan view, (b) shows a side surface, and (c) shows an oblique view. As described with reference to fig. 2, the residue forming portion 4 is formed in a convex shape between two adjacent piezoelectric vibrating reeds 3 in the frame portion 2. As shown in fig. 3, inclined surfaces 41 and 42 based on the etching residue are formed on both sides of the residue forming portion 4. The inclined surfaces 41 and 42 are formed of two inclined surfaces 41 and

inclined surfaces

42 and 42 extending from the two main surfaces toward the center in the thickness direction.

The piezoelectric vibrating reed 3 is formed in its outer shape by wet etching as described later. In this wet etching, an oblique etching residue is formed between an XZ plane orthogonal to the principal surface (XY plane) and a YZ plane orthogonal to the principal surface. In the case of the present embodiment, by forming the residue forming portion 4 protruding from the frame portion 2 in the Y direction, etching residues by the

inclined surfaces

41, 41 and etching residues by the

inclined surfaces

42, 42 are formed so as to be inclined on both outer side surfaces (YZ surfaces) of the residue forming portion 4 and side surfaces (XZ surfaces) of the frame portion 2.

The electrode material formed on the entire frame portion 2 is divided between the first electrode pad 23 and the second electrode pad 24 facing one piezoelectric vibrating reed 3 and between the second electrode pad 24 and the first electrode pad 23 between adjacent piezoelectric vibrating reeds 3. The division between the electrodes is performed by forming the outer shape of the piezoelectric wafer 1 shown in fig. 1, then forming an electrode material as a whole, and then removing the electric material at the divided positions (regions) of the electrodes by exposure in a photolithography step. In this exposure, since the

inclined surfaces

41 and 42 of the residue forming portion 4 are projected by exposure when viewed from the main surface side, the electrode material of the

inclined surfaces

41 and 42 becomes an object to be removed. Therefore, the frame side surface 26 of the frame portion 2 is divided by exposing the

inclined surfaces

41 and 42 formed on both sides of the residue forming portion 4 from both main surface sides. That is, as shown in fig. 3, the first electrode pad 23 and the second electrode pad 24 formed on the frame portion 2 are divided between the main surfaces of the two electrodes and divided by the

inclined surfaces

41 and 42 of the residue forming portion 4 on the frame side surface 26.

As shown in fig. 3, the frame side surface 26, the projection end surface 45, and the two projection side surfaces 46 of the residue forming portion 4 are shown with electrode materials remaining on the frame side surface 26, the projection end surface 45, and the two projection side surfaces 46, as indicated by oblique lines in the same direction as the first electrode pad 23 and the second electrode pad 24 at the portion of the frame side surface 26 connected to the first electrode pad 23 and the second electrode pad 24. However, when the main surfaces of the frame portion 2 and the residue forming portion 4 are exposed after exposure, not only the main surfaces but also certain regions on both main surfaces of the surfaces (the frame side surface 26, the projection end surface 45, and the projection side surface 46) orthogonal to the main surfaces are removed by overexposure. Therefore, even when the starting points of the inclined surfaces 41 and 42 (in fig. 3 b, the apexes of the main surfaces in the triangular shapes forming the inclined surfaces 41 and 42) are located below the main surface (on the other main surface side), the division can be reliably performed by the overexposure. In this way, exposure from an oblique direction is not required to divide the first electrode pad 23 and the second electrode pad 24 of the frame portion 2, and the number of steps can be reduced. In the portions of the projection end surfaces 45 and the two projection side surfaces 26 of the residue forming portion 4 indicated by hatching, the metal material formed in the electrode forming step described later remains, and is separated from the electrodes of the two systems.

Next, a method for manufacturing the piezoelectric wafer 1 configured as described above will be described.

Fig. 4 is a flowchart showing a manufacturing process of the piezoelectric wafer in the first embodiment. First, in the wafer preparation step, a wafer on which the piezoelectric wafer 1 is formed is prepared (step 12). In the wafer preparation step, a wafer having a fixed thickness is prepared by slicing quartz at a predetermined angle.

Next, an outer shape forming step of forming the outer shape of the piezoelectric wafer 1 is performed on the prepared quartz (step 14). In this outline forming step, a part of the prepared wafer is removed, thereby forming the outline of the piezoelectric wafer 1. Specifically, masks (outline masks) of shapes corresponding to the outline shapes of the piezoelectric wafer 1 (except the inclined surfaces 41, 42) are formed on both surfaces of the wafer by a photolithography technique. Thereafter, the wafer is wet-etched to selectively remove the regions not covered by the outline mask, thereby forming the planar external shape of the piezoelectric wafer 1 in which the plurality of piezoelectric vibrating pieces 3 are connected to the frame portion 2 by the links 21 and the residue forming portions 4 are arranged, as shown in fig. 1. At this time, inclined surfaces 41 and 42 as residues are also formed on both sides of the residue forming portion 4 formed to protrude from the frame portion 2 in a range not covered by the outline mask. Next, etching is performed on each of the vibrating

arm portions

7a and 7b of each of the piezoelectric vibrating reeds 3, and grooves 72 are formed on both main surfaces of each of the vibrating

arm portions

7a and 7 b.

Next, an electrode forming step of forming two systems of electrodes on the surface of the wafer having the formed outer shape is performed (step 16).

(a) In this electrode forming step, a metal material to be an electrode is first formed on the entire surface (main surface and side surface) of the wafer having the outer shape by vapor deposition or metal sputtering. As for the metal material, a laminated film having a metal such as chromium as a base layer and a metal such as gold as an upper layer is formed by sputtering or the like for each layer.

(b) Then, the two electrodes (the first electrode pad 23 and the first excitation electrode 91, the second electrode pad 24 and the second excitation electrode 92, the wiring electrode, and the like) are divided and a circuit pattern is formed by a photolithography step (each step of applying a resist film, exposing and developing with an electrode mask, etching a metal, and peeling off the resist film).

That is, after a resist film is applied to the entire surface of the formed metal film, the entire surface region is irradiated from the main surface side with an electrode mask having a shape corresponding to the electrode pattern, and then developed. Thus, the resist films of the electrode portions of the two systems remain in the regions corresponding to the electrode masks in the main surface and the like, and the resist films of the regions where no electrode masks are present and the

inclined surfaces

41 and 42 are removed. The above exposure and development are performed on both main surfaces. Next, the metal layer at the exposed portion is removed by immersing in an etching solution, and then the resist films applied to the surfaces of the electrodes of the divided two systems are removed.

Through the above steps, as shown in fig. 2, the first excitation electrode 91 and the second excitation electrode 92 on the side surfaces of the vibrating

arm portions

7a and 7b are divided. As shown in fig. 3, the first electrode pad 23 and the second electrode pad 24 are divided on the main surface of the frame portion 2. Further, the second electrode pad 24 and the first electrode pad 23 between the adjacent piezoelectric vibrating reeds 3 are divided on the main surface and are divided on the

inclined surfaces

41 and 42. The second electrode pad 24 and the first electrode pad 23 on the frame side surface 26 are reliably divided by overexposure to the boundary portion with the main surface on the frame side surface 26 in addition to the normal exposure to the

inclined surfaces

41 and 42. That is, even if the starting points of the

inclined surfaces

41 and 42 formed in the profile forming step are located below the main surface (on the other main surface side), the divided regions by the normal exposure and the divided regions by the overexposure are connected, and therefore the second electrode pad 24 and the first electrode pad 23 on the frame side surface 26 can be reliably divided. As described above, according to the present embodiment, the step of oblique exposure can be eliminated by the

inclined surfaces

41 and 42 formed by the residue forming portion 4.

Next, a weight metal film forming step is performed for the vibrating

arm portions

7a and 7b of each piezoelectric vibrating reed 3 (step 18). In the weight metal film forming step, a weight metal film for adjusting the frequency is formed on the surface of the widened

portions

71a and 71b of the respective vibrating

arm portions

7a and 7 b. The weight metal film can be formed by, for example, vapor deposition. Further, the weight metal film may be formed simultaneously with each electrode in the electrode forming step (step 16).

Next, a frequency adjustment process for each piezoelectric vibrating reed 3 is performed (step 20). In the frequency adjustment step, a predetermined drive voltage is applied between the first electrode pad 23 and the second electrode pad 24 connected to each piezoelectric vibrating reed 3, and each of the vibrating

arm portions

7a and 7b of the piezoelectric vibrating reed 3 is vibrated, thereby adjusting the frequency of the piezoelectric vibrating reed 3. Specifically, a probe of a measuring device for applying a driving voltage is pressed to each of the first electrode pad 23 and the second electrode pad 24 formed on the frame portion 2. In this state, a driving voltage is applied to the first excitation electrode 91 and the second excitation electrode 92 to vibrate the

vibration arm portions

7a and 7 b. Then, the weight metal films formed on the widened

portions

71a, 71b are partially removed in accordance with the difference between the vibration frequency of each piezoelectric vibrating reed 3 and the target frequency. Thereby, the mass of each of the vibrating

arm portions

7a and 7b changes, and the vibration frequency of each of the vibrating

arm portions

7a and 7b (the frequency of the piezoelectric vibrating reed 3) changes. Therefore, the target frequency of the piezoelectric vibrating reed 3 can be approached.

Through the above steps, the piezoelectric wafer 1 of the present embodiment shown in fig. 1 is formed. The piezoelectric wafer 1 thus formed is subjected to the next singulation step (step 22). In this singulation step, the piezoelectric vibrating reeds 3 connected to the frame portion 2 by the joints 21 are cut and singulated. Specifically, each piezoelectric vibrating reed 3 is bent with respect to the frame portion 2, and is cut at each coupling portion 21. At this time, since the width of the coupling portion 21 is formed so that the base 8 side of the piezoelectric vibrating reed 3 is narrower than the frame portion 2 side, the coupling portion 21 is cut at the base 8 side. As described above, the plurality of piezoelectric vibrating reeds 3 can be manufactured at one time from one wafer.

As described above, according to the piezoelectric wafer 1 of the present embodiment, the residue formation portion 4 protruding from the frame portion 2 is formed between the plurality of piezoelectric vibrating reeds 3 arranged in parallel in the frame portion 2. Moreover, since the

inclined surfaces

41 and 42 are formed also on both side surfaces of the frame portion 2 and the residue forming portion 4 when the outer shape of the piezoelectric wafer 1 is formed, the electrodes on the frame side surface 26 can be easily divided by the

inclined surfaces

41 and 42. That is, without providing the oblique exposure step, the first electrode pad 23 connected to the first excitation electrode 91 of one piezoelectric vibrating reed 3 and the second electrode pad 24 connected to the second excitation electrode 92 of the other piezoelectric vibrating reed 3 of the two adjacent piezoelectric vibrating reeds 3 can be reliably separated by exposure (normal exposure and overexposure) of the

inclined surfaces

41 and 42 of the main surface and the residue forming portion 4 only from the main surface side.

Next, a second embodiment will be explained. Fig. 5 is an enlarged view showing the periphery of the piezoelectric vibrating reed 3 of the piezoelectric wafer 1 in the second embodiment. Fig. 5(a) corresponds to fig. 2(a) in the first embodiment. Fig. 5(b) and (c) are a plan view and a side view of the periphery of the residue forming part 5, which are enlarged further, and correspond to fig. 3(a) and (b).

In the first embodiment described above, the residue forming portion 4 on which the

inclined surfaces

41 and 42 are formed is formed in a shape protruding from the frame portion 2 toward the piezoelectric vibrating reed 3 in order to divide the electrode on the frame side surface 26. In contrast, in the piezoelectric wafer 1 according to the second embodiment, as shown in fig. 5(a), the residue forming portion 5 having a recessed shape is formed in the frame portion 2.

In the recess of the residue forming part 5, as shown in fig. 5(b) and (c), three surfaces, that is, the

inclined surfaces

51 and 52 formed on the side surface 56 of the recess and the inclined surface 53 formed on the bottom surface, are formed as residues. As shown in fig. 5(b), the inclined surfaces 51 to 53 are formed on both sides from both main surfaces of the frame portion 2 toward the center in the thickness direction. In the piezoelectric wafer 1 of the second embodiment as well, the electrodes of the frame side surfaces 26 in the frame portion 2 can be easily divided at the inclined surfaces 51 to 53, as in the first embodiment. That is, without providing the oblique exposure step, the first electrode pad 23 connected to the first excitation electrode 91 of one piezoelectric vibrating reed 3 and the second electrode pad 24 connected to the second excitation electrode 92 of the other piezoelectric vibrating reed 3 of the two adjacent piezoelectric vibrating reeds 3 can be reliably divided by exposure (normal exposure and overexposure) to the inclined surfaces 51 to 53 of the principal surface and the residue forming portion 5.

Fig. 6 is an explanatory view showing a modification of the piezoelectric wafer 1. In the first and second embodiments described above, the case where the first electrode pad 23 and the second electrode pad 24 corresponding to all the piezoelectric vibrating reeds 3 are divided is described. In contrast, in the modification of the piezoelectric wafer 1, as shown in fig. 6, the plurality of first electrode pads 23 are electrically connected to each other. Here, the number of the first electrode pads 23 to be connected may be two or more. Preferably, in terms of the step of frequency adjustment, each frame portion in the X direction to which the piezoelectric vibrating piece 3 is attached is connected to the first electrode pad 23 in two units, or all of the first electrode pads 23 are connected. By electrically connecting the plurality of first electrode pads 23 in this manner, it is possible to measure and adjust the frequency while moving the other probe to the second electrode pad 24 while holding one of the probes of the measuring device fixed to any one of the first electrode pads 23 at the time of frequency adjustment.

In addition, although the case where the plurality of first electrode pads 23 are electrically connected is described in fig. 6, the plurality of second electrode pads 24 may be electrically connected. The present modification can be applied to the second embodiment as well as the first embodiment.

In the above-described embodiment and modification, the piezoelectric wafer 1 is described as being provided with the so-called side-arm type piezoelectric vibrating reed 3 in which the mounting

support arm portions

9a and 9b are formed from the base portion 8 to both outer sides of the vibrating

arm portions

7a and 7b, but various other types of piezoelectric vibrating reeds may be provided.

For example, the piezoelectric wafer 1 may be provided with a so-called cantilever-type piezoelectric vibrating reed in which the supporting arm portion is not present and the base portion 8 is provided with two mounting electrodes for mounting. The piezoelectric wafer 1 may be a so-called center arm type piezoelectric vibrating reed in which one support portion is formed between two vibrating

arm portions

7a and 7b from a base portion 8 and two mounting electrodes for mounting are formed on the support portion. Further, the present invention can be applied to a piezoelectric wafer in which various other types of piezoelectric vibrating reeds such as a quartz vibrating reed cut by reverse mesa AT are connected to a thick plate portion by a connecting leg, in addition to a tuning fork type piezoelectric vibrating reed.

Description of the symbols

1 piezoelectric wafer

2 frame part

21 connecting part (connecting part)

23 first electrode pad

24 second electrode pad

26 frame side

3 piezoelectric vibrating reed

4. 5 residue formation part

41. 42, 51, 52, 53 inclined surface

45 convex end face

46 convex part side surface

56 concave side

7a, 7b vibrating arm

71a, 71b widening

72a, 72b groove parts

8 base

9a, 9b support arm

91 first excitation electrode

92 second excitation electrode.

Claims

1. A piezoelectric wafer is characterized by comprising:

a frame portion;

a plurality of piezoelectric vibrating reeds having vibrating arm portions connected to each other in parallel in the frame portion;

a first excitation electrode and a second excitation electrode formed on the respective piezoelectric vibrating reeds to vibrate the vibrating arm portion;

a first electrode pad formed in the frame portion corresponding to each of the piezoelectric vibrating reeds and electrically connected to the first excitation electrode;

a second electrode pad electrically connected to the second excitation electrode;

a residue forming portion formed between adjacent connecting portions connecting the piezoelectric vibrating reed to the frame portion; and

an inclined surface formed as a residue by the residue forming part;

the first electrode pad formed corresponding to one of the two adjacent piezoelectric vibrating reeds and the second electrode pad formed corresponding to the other piezoelectric vibrating reed are divided into a main surface of the frame portion and an inclined surface formed as the residue.

2. The piezoelectric wafer of claim 1, wherein:

the residue forming portion is formed in a convex shape with respect to the frame portion in a direction in which the piezoelectric vibrating piece is formed,

the inclined surface is formed between the frame portion and both side surfaces of the convex residue forming portion.

3. The piezoelectric wafer of claim 1, wherein:

the residue forming portion is formed in a concave shape recessed in a direction opposite to a direction in which the piezoelectric vibrating reed is formed with respect to the frame portion,

the inclined surfaces are formed at both side surfaces and a bottom surface of the concave shape.

4. A method for manufacturing a piezoelectric wafer according to claim 1, claim 2, or claim 3, wherein:

a wafer preparation step of preparing a wafer;

a profile forming step of forming a profile of the piezoelectric wafer from the prepared wafer;

an electrode forming step of forming a metal material film on the surface of the wafer having the formed outer shape, and then forming two electrodes of a first system of the first excitation electrode and the first electrode pad and a second system of the second excitation electrode and the second electrode pad by photolithography of the metal material; and

a frequency adjustment step of applying a drive voltage from the first electrode pad and the second electrode pad to adjust the frequency of each of the piezoelectric vibrating reeds;

in the electrode forming step, the electrodes of the first system and the second system are divided by performing exposure from a principal surface side using an electrode mask having an electrode pattern shape corresponding to the electrodes of the two systems in photolithography of the metal material.

5. A method of manufacturing a piezoelectric vibrating reed includes:

a method of manufacturing a piezoelectric wafer as defined in claim 4, and

and a singulation step of cutting the piezoelectric vibrating reeds, which are arranged in the frame portion and connected in plurality, from the manufactured piezoelectric wafer.