JP2013021601A - Piezoelectric vibrating piece, method for manufacturing piezoelectric vibrating piece, piezoelectric vibrator, oscillator, electronic appliance, and radio-controlled timepiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost piezoelectric vibrating piece that requires fewer man-hours in an electrode forming process, and a simpler manufacturing apparatus, than in the prior art, and to provide a method for manufacturing the piezoelectric vibrating piece, a piezoelectric vibrator, an oscillator, an electronic appliance, and a radio-controlled timepiece, using the piezoelectric vibrator.SOLUTION: A piezoelectric vibrating piece 4 includes: excitation electrodes 13 and 14 that are formed on a pair of vibrating arms 10 and 11; mount electrodes 16 and 17 that are electrically connected to the outside; lead-out electrodes 19 and 20 that connect the excitation electrodes 13 and 14 and the mount electrodes 16 and 17, respectively. Through-holes 8 and 9 are formed in the vibrating arms 10 and 11, respectively. The excitation electrodes 13 and 14 are respectively formed on inner side surfaces 8a, 8c, 9a, and 9c of the through-holes 8 and 9 and on outer side surfaces 10a, 10b, 11a, and 11b facing the respective inner side surfaces 8a, 8c, 9a, and 9c. The mount electrodes 16 and 17 and the lead-out electrodes 19 and 20 are formed on one main surface F of a base 12.

Description

  The present invention relates to a piezoelectric vibrating piece, a method of manufacturing a piezoelectric vibrating piece, a piezoelectric vibrator, an oscillator using the piezoelectric vibrator, an electronic device, and a radio timepiece.

  In cellular phones and portable information terminal devices, piezoelectric vibrators using quartz or the like are used as time sources, timing sources of control signals, reference signal sources, and the like. There are various types of piezoelectric vibrators of this type. One of them is a piezoelectric vibrator in which a so-called tuning fork type piezoelectric vibrating piece in which a pair of vibrating arms are extended from a base is enclosed in a package. It has been known.

  By the way, in recent years, with the downsizing of devices to be mounted, further downsizing of the piezoelectric vibrating piece is desired. As a method for reducing the size of the piezoelectric vibrating piece while keeping the CI value (Crystal Impedance) of the piezoelectric vibrating piece low, a method of forming grooves on both main surfaces of the vibrating arm is widely known (for example, patents). Reference 1).

FIG. 22 is an explanatory diagram of the prior art, and is a cross-sectional view along a direction perpendicular to the longitudinal direction of the vibrating arm portion 203 of Patent Document 1. In FIG.
As shown in FIG. 22, the vibrating arm 203 has a substantially H-shaped cross section, and a first excitation electrode 210 and a second excitation electrode 211 are formed on the outer surface of the vibrating arm 203. Yes. The pair of excitation electrodes 210 and 211 are formed on the inner side surfaces 205 a and 206 a of the groove portions 205 and 206 and the outer side surface 203 a of the vibrating arm portion 203 so that an electric field can be generated along the width direction of the vibrating arm portion 203. .
The pair of excitation electrodes 210 and 211 is electrically connected to a mount electrode (not shown) formed on the main surface of the base (not shown) via an extraction electrode (not shown). The mount electrode is mounted on the internal electrode of the package to form a piezoelectric vibrator.

The electrode forming process for forming the excitation electrode, the extraction electrode, and the mount electrode is as follows.
First, an electrode metal film that will be each subsequent electrode is formed on a piezoelectric plate formed on the outer shape of the piezoelectric vibrating piece by sputtering (metal film forming step).
Next, a photosensitive material such as a photoresist is applied on the electrode metal film to form a photosensitive material film (photosensitive material film forming step).
Subsequently, the photosensitive material film is exposed by a photolithography technique (exposure process), and is developed by being immersed in a developer (development process), thereby forming a pattern of the photosensitive material film.
Finally, the electrode metal film is etched using the pattern of the photosensitive material film as a mask (metal film etching step). Thereby, the electrode metal film other than the region protected by the photosensitive material film is selectively removed, and each electrode of the piezoelectric vibrating piece is formed.

Here, as shown in FIG. 22, the groove portion 205 on one side is formed on one main surface of the vibrating arm portion 203, and the groove portion 206 on the other side is formed on the other main surface of the vibrating arm portion 203. Yes. Therefore, in order to form the first excitation electrode 210 on the inner side surfaces 205a and 206a of the groove portions 205 and 206, each step of the electrode forming step is performed on the main surface on one side and the main surface on the other side of the piezoelectric plate. ing.
Specifically, in the metal film forming step, after the electrode metal film is formed on one main surface of the piezoelectric plate, the piezoelectric plate is reversed and the electrode metal is formed on the other main surface. By forming a film, electrode metal films are formed on both principal surfaces of the piezoelectric plate. In the photosensitive material film forming step, as in the metal film forming step, after forming the photosensitive material film on the main surface on one side of the piezoelectric plate, the piezoelectric plate is reversed and the main surface on the other side On the other hand, a photosensitive material film is formed on both main surfaces of the piezoelectric plate by forming a photosensitive material film. In the exposure process, ultraviolet rays are irradiated to both main surfaces of the piezoelectric plate.

JP 2002-76806 A

However, the above electrode forming process has the following problems.
In the metal film forming step and the photosensitive material film forming step, the metal film for the electrode and the photosensitive material film are separately formed on the main surface on one side and the main surface on the other side. There is a tendency. In the exposure process, a double-side exposure apparatus is required, and a pair of photomasks for forming a pattern of the photosensitive material film must be prepared and arranged at predetermined positions on both main surfaces of the piezoelectric plate. . Therefore, the exposure process is not only costly but also complicated and requires a lot of man-hours. For this reason, the electrode forming process of the prior art has a problem that the manufacturing cost is high.

  Therefore, the present invention can reduce the man-hours of the electrode forming process and simplify the manufacturing apparatus as compared with the prior art. The piezoelectric vibrating piece, the method for manufacturing the piezoelectric vibrating piece, the piezoelectric vibrator, and the piezoelectric vibrator can be reduced in cost. It is an object to provide an oscillator, an electronic device, and a radio timepiece that are used.

  In order to solve the above problems, a piezoelectric vibrating piece according to the present invention includes a piezoelectric plate having a pair of vibrating arm portions arranged side by side and a base portion to which the pair of vibrating arm portions are connected, and the vibrating arm. An excitation electrode that is formed on the base and vibrates the vibrating arm, a mount electrode that is formed on the base and is electrically connected to the outside, and an extraction electrode that connects the excitation electrode and the mount electrode. In the piezoelectric vibrating piece, the vibrating arm portion is formed with a through-hole penetrating one side and the other side in the thickness direction of the piezoelectric plate and extending along a longitudinal direction of the vibrating arm portion. The excitation electrode is formed on an inner surface of the through hole along the longitudinal direction and an outer surface of the vibrating arm portion facing the inner surface, and the mount electrode and the extraction electrode are Main only on one side of the base It is characterized in that it is formed.

According to the present invention, by forming a through-hole in the vibrating arm portion, an inner side surface that connects the main surface on one side and the main surface on the other side of the vibrating arm portion is formed. Therefore, by applying a metal material and a photosensitive material from one side of the piezoelectric plate, an electrode metal film and a photosensitive material film can be formed on the inner surface along the longitudinal direction of the vibrating arm portion, and an excitation electrode is formed. it can.
Further, the mount electrode and the extraction electrode are formed on the main surface only on one side of the base, and are not formed on the main surface on the other side. Therefore, by applying a metal material and a photosensitive material from one side of the piezoelectric plate, a metal film for an electrode and a photosensitive material film can be formed on the main surface on one side of the base, and a mount electrode and a lead electrode can be formed. .
Further, since the photosensitive material film is not formed on the other main surface of the piezoelectric plate, the photosensitive material film may be exposed only from one side of the piezoelectric plate. This eliminates the need to introduce an expensive double-side exposure apparatus or prepare a pair of photomasks and place them on both main surfaces of the piezoelectric plate.
In this way, each electrode can be formed by forming a metal film for an electrode, forming a photosensitive material film, and exposing only from one side of the piezoelectric plate. Therefore, in the present invention, the number of man-hours is compared with the prior art in which each electrode is formed by forming a metal film for an electrode, forming a photosensitive material film and exposing from both sides of one side and the other side of the piezoelectric plate. And a manufacturing apparatus can be simplified, and a low-cost piezoelectric vibrating piece can be formed.

  The excitation electrode is formed over the entire thickness of the vibrating arm.

  According to the present invention, an electric field can be formed in a direction orthogonal to the inner side surface of the through hole and the outer side surface of the vibrating arm portion over the entire thickness direction of the vibrating arm portion. Therefore, since the vibrating arm portion can be vibrated efficiently, a piezoelectric vibrating piece with little loss can be formed.

  In addition, a plurality of the through holes are formed in each of the vibrating arm portions.

  According to the present invention, the rigidity of the vibrating arm portion can be arbitrarily set by adjusting the number of through holes formed in each vibrating arm portion, the size of each through hole, the formation position of each through hole, and the like. Therefore, the drive level characteristic depending on the rigidity of the vibrating arm can be set to a desired characteristic.

  The method for manufacturing a piezoelectric vibrating piece according to the present invention includes: an outer shape forming step of forming an outer shape of the piezoelectric plate and the through hole from a piezoelectric wafer; and a metal film for an electrode is patterned by a photolithography technique; An electrode forming step for forming each electrode, wherein the electrode forming step includes a metal film forming step for forming the electrode metal film on the surface of the piezoelectric plate, and a photosensitivity layer on the electrode metal film. A photosensitive material film forming step for forming a photosensitive material film, and an exposure step for exposing the photosensitive material film using a photomask on which a pattern corresponding to each electrode is formed, and the metal The film forming step, the photosensitive material film forming step, and the exposure step are performed only from the one side of the piezoelectric plate.

According to the present invention, the metal film forming step, the photosensitive material film forming step, and the exposure step are performed only from one side of the piezoelectric plate, so the metal film is formed from both sides of the one side and the other side of the piezoelectric plate. Compared with the prior art that performs the process, the photosensitive material film forming process, and the exposure process, the number of steps can be reduced and the manufacturing apparatus can be simplified. Therefore, a low-cost piezoelectric vibrating piece can be formed.
By the way, in the prior art, since the metal film forming process is performed twice from one side and the other side of the piezoelectric plate, the electrode metal film formed on the outer surface of the vibrating arm portion is thicker than necessary. There was a risk of becoming. However, according to the present invention, since the metal film forming process is performed only once from one side of the piezoelectric plate, the electrode metal film formed on the outer surface of the vibrating arm portion becomes thicker than necessary. Can be prevented. In particular, it is possible to prevent the electrode metal film from becoming unnecessarily thick at the narrow crest formed by the outer surface of the pair of vibrating arms and the outer surface of the base. It can suppress that a film | membrane remains. As a result, it is possible to prevent the occurrence of manufacturing defects such as short-circuiting of excitation electrodes in the portion.

  The outer shape forming step includes forming a mask metal film on both main surfaces of the piezoelectric wafer, and forming a mask pattern of the piezoelectric plate from the mask metal film by a photolithography technique; And a wafer etching step of etching the piezoelectric wafer from both sides of the one side and the other side of the piezoelectric wafer via the mask pattern.

According to the present invention, since the wafer etching process is performed from both one side and the other side of the piezoelectric wafer, the outer shape can be formed uniformly along the thickness direction of the piezoelectric plate. Accordingly, since the pair of vibrating arm portions can be formed with high accuracy, a piezoelectric vibrating piece having stable frequency characteristics can be formed.
In addition, according to the present invention, the outer shape of the piezoelectric vibrating piece and the through hole can be simultaneously formed in a single wafer etching process. Therefore, the wafer etching process can be simplified as compared with the conventional technique in which the outer shape of the piezoelectric vibrating piece is etched and then half-etched to form the grooves 205 and 206 (see FIG. 22).

The piezoelectric vibrator of the present invention is characterized in that the above-described piezoelectric vibrating piece is housed in a cavity formed by a base substrate and a lid substrate.
According to the present invention, since the low-cost piezoelectric vibrating reed that can reduce the man-hour of the electrode forming process and simplify the manufacturing apparatus is provided, a low-cost piezoelectric vibrator can be provided.

The oscillator according to the present invention is characterized in that the above-described piezoelectric vibrator is electrically connected to an integrated circuit as an oscillator.
The electronic apparatus according to the present invention is characterized in that the above-described piezoelectric vibrator is electrically connected to a time measuring unit.
The radio-controlled timepiece of the present invention is characterized in that the above-described piezoelectric vibrator is electrically connected to a filter unit.

  According to the oscillator, electronic device, and radio timepiece of the present invention, it is possible to provide a low-cost oscillator, electronic device, and radio timepiece.

According to the present invention, by forming a through-hole in the vibrating arm portion, an inner side surface that connects the main surface on one side and the main surface on the other side of the vibrating arm portion is formed. Therefore, by applying a metal material and a photosensitive material from one side of the piezoelectric plate, an electrode metal film and a photosensitive material film can be formed on the inner surface along the longitudinal direction of the vibrating arm portion, and an excitation electrode is formed. it can.
Further, the mount electrode and the extraction electrode are formed on the main surface only on one side of the base, and are not formed on the main surface on the other side. Therefore, by applying a metal material and a photosensitive material from one side of the piezoelectric plate, a metal film for an electrode and a photosensitive material film can be formed on the main surface on one side of the base, and a mount electrode and a lead electrode can be formed. .
Further, since the photosensitive material film is not formed on the other main surface of the piezoelectric plate, the photosensitive material film may be exposed only from one side of the piezoelectric plate. This eliminates the need to introduce an expensive double-side exposure apparatus or prepare a pair of photomasks and place them on both main surfaces of the piezoelectric plate.
In this way, each electrode can be formed by forming a metal film for an electrode, forming a photosensitive material film, and exposing only from one side of the piezoelectric plate. Therefore, in the present invention, the number of man-hours is compared with the prior art in which each electrode is formed by forming a metal film for an electrode, forming a photosensitive material film and exposing from both sides of one side and the other side of the piezoelectric plate. And a manufacturing apparatus can be simplified, and a low-cost piezoelectric vibrating piece can be formed.

It is the top view seen from one side of a piezoelectric vibrating piece. It is the top view seen from the other side of the piezoelectric vibrating piece. It is sectional drawing along the AA line of FIG. It is a perspective view of the connection part vicinity of a vibrating arm part and a base. It is the top view seen from one side of the piezoelectric vibrating piece in the modification of an embodiment. It is a flowchart of the manufacturing process of a piezoelectric vibrating piece. It is a flowchart of an external shape formation process. It is explanatory drawing of a mask pattern formation process. It is explanatory drawing of a mask pattern formation process. It is explanatory drawing of a mask pattern. It is sectional drawing along the BB line of FIG. It is a flowchart of an electrode formation process. It is explanatory drawing of a metal film forming process and a photoresist film forming process. It is explanatory drawing of an exposure process. It is an external perspective view of a piezoelectric vibrator. It is an internal block diagram of a piezoelectric vibrator, and is a plan view in a state where a lid substrate is removed. It is sectional drawing along CC line of FIG. It is a disassembled perspective view of a piezoelectric vibrator. It is a block diagram which shows one Embodiment of an oscillator. It is a lineblock diagram showing one embodiment of electronic equipment. It is a block diagram which shows one Embodiment of a radio timepiece. It is explanatory drawing of the piezoelectric vibration piece of a prior art.

(Piezoelectric vibrating piece)
Hereinafter, a piezoelectric vibrating piece according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view seen from one side of the piezoelectric vibrating piece 4.
FIG. 2 is a plan view seen from the other side of the piezoelectric vibrating piece 4.
3 is a cross-sectional view taken along the line AA in FIG. 2 and 3, the thickness of each electrode formed is exaggerated.

  In the following description of the piezoelectric vibrating piece 4, description is made using an X, Y, Z orthogonal coordinate system as necessary. Specifically, the direction in which the vibrating arms 10 and 11 are arranged is the X direction, the central axis in the X direction is O, the central axis O side of the piezoelectric vibrating piece 4 is the −X side, and the outer side is the + X side. Yes. In addition, the longitudinal direction of the vibrating arm portions 10 and 11 is the Y direction, the proximal end side is the −Y side, and the distal end side is the + Y side. Further, the thickness direction of the piezoelectric vibrating reed 4 is the Z direction, one side is the + Z side, and the other side is the −Z side. Further, the + Z side surface of the piezoelectric vibrating piece 4 is F, and the −Z side surface is S.

As shown in FIG. 1, the piezoelectric vibrating reed 4 of this embodiment is a tuning fork type vibrating reed formed from a piezoelectric material such as crystal, lithium tantalate, or lithium niobate, and when a predetermined voltage is applied. It will vibrate.
The piezoelectric vibrating reed 4 has a pair of vibrating arm portions 10 and 11 (first vibrating arm portion 10 and second vibrating arm portion 11) arranged side by side and a pair of vibrating arm portions 10 and 11 connected to each other. And a base 12.

The pair of vibrating arm portions 10 and 11 have a certain width in the X direction, are arranged side by side substantially parallel to the X direction, and extend in the Y direction along the central axis O. The pair of vibrating arm portions 10 and 11 are formed with through holes 8 and 9 that pass through the + Z side surface F and the −Z side surface S of the vibrating arm portions 10 and 11, respectively.
As shown in FIG. 1, the through holes 8 and 9 are formed in a substantially rectangular shape in plan view in the Z direction, have a certain width in the X direction, and extend along the Y direction. The −Y side ends of the through holes 8 and 9 are arranged in the vicinity of the connection portion between the vibrating arm portions 10 and 11 and the base portion 12. The + Y side ends of the through holes 8 and 9 are disposed at the approximate center in the Y direction of the vibrating arm portions 10 and 11.

  In the connection portion between the base portion 12 and the vibrating arm portions 10 and 11, the region surrounded by the + Y side surface of the base portion 12, the −X side surface 10 b of the vibrating arm portion 10, and the −X side surface 11 b of the vibrating arm portion 11 includes 25 is formed. Moreover, the part 25 is formed in the Z direction planar view substantially U shape.

(Excitation electrode)
As shown in FIG. 1, the pair of excitation electrodes 13 and 14 are formed by patterning on the outer surfaces of the vibrating arm portions 10 and 11 while being electrically separated from each other.
As shown in FIG. 2, the inner side surfaces 8a and 9a along the Y direction of the through holes 8 and 9, the second inner side surfaces 8b and 9b along the X direction, and the vibrating arm portions 10 and 11 as shown in FIG. On the + Z side surface F, a pair of excitation electrodes 13 and 14 are formed. The excitation electrodes 13 and 14 are formed of a single-layer conductive film such as chromium, for example. The excitation electrodes 13 and 14 are electrodes that vibrate the vibrating arm portions 10 and 11 at a predetermined resonance frequency in a direction approaching or separating from each other when a voltage is applied.

  Specifically, the first excitation electrode 13 mainly includes the inner side surfaces 8a to 8d of the through-hole 8 of the first vibrating arm portion 10, the + X side surface 11a of the second vibrating arm portion 11, and the second It is formed on the −X side surface 11b of the vibrating arm portion 11 (see FIGS. 1 to 3). The second excitation electrode 14 is mainly composed of the inner side surfaces 9a to 9d of the through hole 9 of the second vibrating arm portion 11, the + X side surface 10a of the first vibrating arm portion 10, and the first vibrating arm portion. 10 -X side surface 10b (see FIGS. 1 to 3). As shown in FIG. 2, the excitation electrodes 13 and 14 are not formed on the −Z side surface S.

  In the present embodiment, the first excitation electrode 13 is formed on the inner side surfaces 8 a to 8 d of the through hole 8, and the second excitation electrode 14 is formed on the inner side surfaces 9 a to 9 d of the through hole 9. The excitation electrode 13 may be formed at least on the inner side surfaces 8a and 8c along the Y direction, and the excitation electrode 14 may be formed at least on the inner side surfaces 9a and 9c along the Y direction.

  By forming the excitation electrodes 13 and 14 in this way, as shown in FIG. 3, the excitation electrode 13 formed on the inner side surfaces 8 a and 8 c of the through hole 8 and the + X side surface 10 a of the first vibrating arm portion 10. And the excitation electrode 14 formed on the −X side surface 10b. In addition, the excitation electrode 14 formed on the inner side surfaces 9a and 9c of the through hole 9 and the excitation electrode 13 formed on the + X side surface 11a and the −X side surface 11b of the second vibrating arm portion 11 can be opposed to each other. . Then, by applying a voltage to the excitation electrodes 13 and 14, an electric field can be formed along the X direction of the vibrating arm portions 10 and 11, and the vibrating arm portions 10 and 11 can be vibrated.

FIG. 4 is a perspective view of the vicinity of the connecting portion between the vibrating arm portions 10 and 11 and the base portion 12.
As shown in FIG. 4, the second excitation electrode 14 formed on the −X side surface 10 b of the first vibrating arm unit 10 and the first electrode formed on the −X side surface 11 b of the second vibrating arm unit 11. The excitation electrode 13 is opposed to the excitation electrode 13 with the portion 25 interposed therebetween. In addition, no electrode is formed on the surface of the portion 25, and the first excitation electrode 13 and the second excitation electrode 14 are also formed by patterning in a state where they are also electrically separated in the portion 25. .

(Mount electrode)
As shown in FIG. 1, a pair of mount electrodes 16 and 17 are formed on the −Y side of the + Z side surface F of the base portion 12 with the central axis O interposed therebetween.
The mount electrodes 16 and 17 are laminated films of chromium and gold, and are formed by forming a chromium film having good adhesion with crystal as a base layer and then forming a gold thin film as a finishing layer on the surface. The However, the present invention is not limited to this. For example, after forming chromium and nichrome as a base layer, a gold thin film may be further formed as a finishing layer on the surface. As shown in FIG. 2, the mount electrodes 16 and 17 are not formed on the −Z side surface S.

(Extraction electrode)
As shown in FIG. 1, lead electrodes 19 and 20 that electrically connect the excitation electrodes 13 and 14 and the mount electrodes 16 and 17 are formed on the + Z side surface F of the base 12.
The lead electrode 19 connects the mount electrode 16 and the first excitation electrode 13 formed on the first vibrating arm portion 10, and is formed so as to straddle the central axis O.
The lead electrode 20 connects the mount electrode 17 and the second excitation electrode 14 formed on the first vibrating arm 10 and is formed along the Y direction on the + X side.

  The lead electrodes 19 and 20 are formed of a single layer film of chromium of the same material as the base layer of the mount electrodes 16 and 17. Thereby, the extraction electrodes 19 and 20 can be formed simultaneously with the formation of the underlying layer of the mount electrodes 16 and 17. However, the present invention is not limited to this case. For example, the extraction electrodes 19 and 20 may be formed of nickel, aluminum, titanium, or the like. As shown in FIG. 2, the extraction electrodes 19 and 20 are not formed on the −Z side surface S.

  Further, as shown in FIG. 1, the tip portions of the vibrating arms 10 and 11 are provided with a rough adjustment film 21a and a fine adjustment film 21b for adjusting (frequency adjustment) so as to vibrate within a predetermined frequency range. A weight metal film 21 is formed. By adjusting the frequency using the weight metal film 21, the frequency of the pair of vibrating arm portions 10 and 11 can be kept within the range of the nominal frequency of the device. As shown in FIG. 2, the weight metal film 21 is not formed on the −Z side surface S.

(Modified example of embodiment, piezoelectric vibrating piece having a plurality of through holes in each vibrating arm)
Next, a modification of this embodiment will be described.
FIG. 5 is an explanatory diagram of the piezoelectric vibrating reed 4 according to a modification of the present embodiment.
In the above-described embodiment, one through hole 8 is formed in the first vibrating arm portion 10, and one through hole 9 is formed in the second vibrating arm portion 11. On the other hand, in the modification of the present embodiment, two through holes 8A and 8B are formed in the first vibrating arm portion 10, and two through holes 9A and 9B are formed in the second vibrating arm portion 11. It differs in that it is formed. In addition, description is abbreviate | omitted about the component similar to embodiment. The through holes 8A and 8B formed in the first vibrating arm portion 10 and the through holes 9A and 9B formed in the second vibrating arm portion 11 have the same shape. Therefore, in the following, the through holes 8A and 8B formed in the first vibrating arm portion 10 will be described, and the detailed description of the through holes 9A and 9B formed in the second vibrating arm portion 11 will be omitted. Yes.

As shown in FIG. 5, the vibrating arm portion 10 is formed with a through hole 8 </ b> A and a through hole 8 </ b> B that penetrate the + Z side surface F and the −Z side surface S of the vibrating arm portions 10 and 11.
The through hole 8A and the through hole 8B are formed in the same shape that is substantially rectangular in a plan view in the Z direction, have a certain width in the X direction, and extend along the Y direction.
The through holes 8A and the through holes 8B are formed in a line along the Y direction. A through hole 8 </ b> A is formed on the −Y side of the vibrating arm portion 10, and the −Y side end of the through hole 8 </ b> A is disposed in the vicinity of the connection portion between the vibrating arm portion 10 and the base portion 12. Further, a through hole 8B is formed on the through hole 8A + Y side, and the + Y side end of the through hole 8B is disposed at a substantially center in the Y direction of the vibrating arm portion 10.

  Here, a drive level characteristic is known as a characteristic depending on the rigidity of the vibrating arm portions 10 and 11. The drive level characteristic means a fluctuation characteristic of the vibration frequency of the piezoelectric vibrating piece 4 with respect to a fluctuation of the driving voltage. Specifically, when the voltage applied to the piezoelectric vibrating piece 4 is increased from V1 to V2, the frequency increases from f0 to f1. When the voltage applied to the piezoelectric vibrating reed 4 is returned from V2 to V1, the frequency does not return from f1 to f0 frequency, but becomes a value f2 lower than f0. The characteristic of the fluctuation value Δf (the difference between f0 and f2) of the vibration frequency is referred to as a drive level characteristic. It can be said that the smaller the fluctuation width of Δf, the better the drive level characteristics and the higher the performance of the piezoelectric vibrating reed 4.

  According to this modification, since the wall 6 (6a) along the X direction is formed between the through hole 8A and the through hole 8B, the total opening area of the through hole 8A and the through hole 8B The rigidity of the vibrating arm portions 10 and 11 can be ensured as compared with the case where one through hole 8 having the same opening area is formed. Thereby, the piezoelectric vibrating piece 4 having a desired drive level characteristic can be formed.

(Method for manufacturing piezoelectric vibrating piece)
Next, a method for manufacturing the piezoelectric vibrating reed 4 described above will be described below with reference to a flowchart.
FIG. 6 is a flowchart of the manufacturing process of the piezoelectric vibrating piece 4.
As shown in FIG. 6, in the manufacturing process of the piezoelectric vibrating reed 4 of this embodiment, after preparing a crystal wafer (corresponding to “piezoelectric wafer” in claims) (S100), the piezoelectric vibrating reed 4 subsequent to the crystal wafer is prepared. An outer shape forming step S110 for forming a plurality of vibrating piece outer shape portions (corresponding to “piezoelectric plates” in the claims), an electrode forming step S120 for forming each electrode on a crystal wafer, and a frequency adjusting step for adjusting the resonance frequency S130 and a fragmentation step S140 for separating the plurality of piezoelectric vibrating reeds 4 from one crystal wafer. Details of each step will be described below.

  First, polishing is completed, and a crystal wafer finished to a predetermined thickness with high accuracy is prepared (S100). Next, an outer shape forming step S110 is performed in which the resonator element outer portion 4a having the outer shape of the piezoelectric resonator element 4 (see FIG. 1) and the through holes 8 and 9 (see FIG. 11) are formed on the quartz wafer.

(Outline forming step S110)
FIG. 7 is a flowchart of the outer shape forming step S110.
As shown in FIG. 7, the outer shape forming step S110 includes a mask pattern forming step S112 for forming a mask pattern having the outer shape of the piezoelectric vibrating reed 4 from a mask metal film formed on the surface of the quartz wafer, and a quartz wafer. Wafer etching step S114 for etching.

(Mask pattern forming step S112)
FIG. 8 is an explanatory diagram of the mask pattern forming step S112.
As shown in FIG. 8, in the mask pattern forming step S112, first, a mask metal film 74 is formed on each of the + Z side surface F and the -Z side surface S of the crystal wafer W (S112A). The mask metal film 74 is a laminated film of a base film 74a made of chromium and a finish film 74b made of gold, for example, and is formed by a sputtering method, a vapor deposition method, or the like.

  Next, a photoresist film 75 is formed over the mask metal film 74 (S112B). Specifically, the photoresist film 75 is formed by applying a photoresist material on the mask metal film 74 by spin coating or the like, and then pre-baking the photoresist material to evaporate the organic solvent. .

FIG. 9 is an explanatory diagram of the mask pattern forming step S112.
Next, as shown in FIG. 9, a resist pattern is formed on the photoresist film 75 by using a photolithography technique (S112C). Photoresist materials include a positive resist in which an exposed portion is softened and removed, and a negative resist in which an exposed portion is cured and remains. In this embodiment, a positive resist is used. An example will be described.

  In the mask pattern forming step S112, an exposure mask 80 is disposed, and the photoresist film 75 is exposed by irradiating ultraviolet rays K from the + Z side and the −Z side of the crystal wafer W. The exposure mask 80 is formed in a region corresponding to the outer shape of the piezoelectric vibrating piece 4. When the exposure is completed, the exposure mask 80 is removed.

  Next, the quartz wafer W is immersed in a developer, and the photoresist film 75 is developed. As a result, only the photoresist film 75 in the region exposed to the ultraviolet K is selectively removed, and a plurality of resist patterns in which the photoresist film 75 remains in the outer shape of the piezoelectric vibrating piece 4 is formed.

FIG. 10 is an explanatory diagram of a mask pattern.
Subsequently, the mask metal film 74 is etched using the resist pattern of the photoresist film 75 as a mask, and the mask metal film 74 that is not masked is selectively removed (S112D). Then, the photoresist film 75 is removed after the etching process. Thereby, as shown in FIG. 10, a mask pattern corresponding to the outer shape of the piezoelectric vibrating piece 4 can be formed. Thus, the mask pattern forming step S112 is completed.

(Wafer Etching Step S114)
11 is a cross-sectional view taken along line BB in FIG.
Finally, as shown in FIG. 11, a wafer etching step S114 for etching the crystal wafer W through the mask pattern is performed. In the wafer etching step S114 of the present embodiment, so-called wet etching is performed in which etching is performed by immersion in a fluorine-based etching solution, for example. As a result, a plurality of vibrating piece outer portions 4 a having the through holes 8 and 9 and serving as the subsequent piezoelectric vibrating piece 4 are formed. The plurality of vibrating piece outer portions 4a are in a state of being connected to the crystal wafer W through a connecting portion (not shown) until the fragmenting step S140 to be performed later.
Here, since the etching process is performed from both the + Z side and the −Z side of the crystal wafer W, the piezoelectric vibrating reed 4 formed later has a uniform outer shape along the Z direction. Therefore, since the pair of vibrating arm portions 10 and 11 can be formed with high accuracy, the piezoelectric vibrating piece 4 having stable frequency characteristics can be formed.
Thus, the outer shape forming step S110 is completed.

(Electrode forming step S120)
FIG. 12 is a flowchart of the electrode formation step S120.
Next, the electrodes of the excitation electrodes 13 and 14, the extraction electrodes 19 and 20, and the mount electrodes 16 and 17 (both see FIG. 1) are formed on the surface of the crystal wafer W on which the resonator element outer shape portion 4 a is formed. An electrode forming step S120 is performed.
As shown in FIG. 12, the electrode forming step S120 includes a metal film forming step S121 for forming an electrode metal film on the surface of the crystal wafer W, and a photoresist film (photosensitive material film) overlaid on the electrode metal film. ) A photoresist film forming step S123 (photosensitive material film forming step), an exposure step S125 for exposing the photoresist film, and a development for selectively removing the photoresist film to form a mask pattern Step S127 and a metal film etching step S129 for etching the metal film for electrodes through the mask pattern to form each electrode.

(Metal film forming step S121)
FIG. 13 is an explanatory diagram of the metal film forming step S121 and the photoresist film forming step S123.
As shown in FIG. 13, in the electrode forming step S120, a metal film forming step S121 for forming an electrode metal film 84 to be the excitation electrodes 13 and 14 (see FIG. 1) on the crystal wafer W is performed. In the present embodiment, a metal material is applied only from the + Z side of the quartz wafer W by a sputtering method, a vacuum deposition method, or the like, and the electrode metal film 84 to be each electrode later is formed.
In the electrode metal film 84, a chromium film having good adhesion to the crystal is formed as the base film 84a. Further, a gold thin film is formed as a finishing film 84b on the base film 84a.
Here, as shown in FIG. 13, the through-holes 8 and 9 are formed in the crystal wafer W. Therefore, in the metal film forming step S121, the inner surfaces 8a to 8d and 9a to 9d (see FIG. 1) of the through holes 8 and 9 are entirely applied by applying chromium and gold only from the + Z side of the crystal wafer W. An electrode metal film 84 can be formed.

By the way, in the prior art, as shown in FIG. 22, the through-hole is not formed in the vibrating arm portion 203, and the groove portions 205 and 206 are formed on both main surfaces of the vibrating arm portion 203. Therefore, in the prior art, in the metal film forming step S121, in order to form the electrode metal film on the inner surfaces 205a and 206a of the grooves 205 and 206 formed in the crystal wafer, the + Z side and −Z side of the crystal wafer are formed. It is necessary to perform the metal film forming step S121 twice from the side. As a result, the film thickness of the electrode metal film 84 formed on the outer surface 203a of the vibrating arm portion 203 may be unnecessarily thick.
However, according to the present embodiment, as shown in FIG. 13, since the metal film forming step S121 is performed only once from the + Z side of the crystal wafer W, the crystal wafer W is formed on the outer surface of the resonator element outer portion 4a. It is possible to prevent the electrode metal film 84 from becoming thicker than necessary. In particular, it is possible to prevent the electrode metal film 84 from becoming unnecessarily thick at the portion that becomes the rear portion 25 (see FIG. 4) of the outer surface of the resonator element outer portion 4a. Therefore, in the subsequent metal film etching step S129, it is possible to suppress the electrode metal film 84 from remaining in the portion that becomes the subsequent back portion 25 (see FIG. 4). Thereby, it is possible to prevent the occurrence of manufacturing defects such as short-circuiting of the excitation electrodes 13 and 14 (see FIG. 4) in the portion 25.

(Photoresist film forming step S123)
Subsequently, a photoresist film forming step S123 for forming a photoresist film 85 on the electrode metal film 84 is performed. As described above, the photoresist material includes a positive resist in which the exposed portion is softened and removed, and a negative resist in which the exposed portion is cured and remains. Type resist is deposited. The photoresist film 85 is deposited on the electrode metal film 84 by spray coating from the + Z side of the crystal wafer W.

  Here, as described above, the through-holes 8 and 9 are formed in the crystal wafer W. Therefore, in the photoresist film forming step S123, as in the metal film forming step S121, by applying a photoresist material only from the + Z side of the crystal wafer W, the inner side surfaces 8a to 8d of the through holes 8, 9 A photoresist film 85 can be formed over the electrode metal film 84 over the entirety of 9a to 9d (see FIG. 1).

(Exposure step S125)
FIG. 14 is an explanatory diagram of the exposure step S125.
As shown in FIG. 14, in the exposure step S <b> 125, the photomask 90 having the opening 90 a is set in a state facing the photoresist film 85.

  In the exposure step S125, the photoresist film 85 is irradiated with ultraviolet rays K through the opening 90a. The opening 90a of the photomask 90 is a region where the photoresist film 85 is desired to be removed, and is formed corresponding to a region where the electrode metal film 84 is desired to be removed in a metal film etching step S129 described later. In other words, the opening 90a of the photomask 90 is formed corresponding to a region where the excitation electrodes 13 and 14, the extraction electrodes 19 and 20 and the mount electrodes 16 and 17 electrodes (both see FIG. 1) are not formed. Is done. When the exposure is completed, the photomask 90 is removed.

  Here, in the photoresist film forming step S123, a photoresist film is formed only from the + Z side of the crystal wafer W. Therefore, the photoresist film 85 is mainly formed on the + Z side surface F of the crystal wafer W and is not formed on the −Z side surface S. Therefore, since the photoresist film 85 has only to be exposed from the + Z side of the quartz wafer W, an expensive double-side exposure apparatus is introduced as in the prior art, or a pair of photomasks are prepared and + Z of the quartz wafer W is prepared. There is no need to place them at predetermined positions on the side surface F and the -Z side surface S.

(Development step S127)
Subsequently, the quartz wafer W on which the photoresist film 85 is formed is immersed in a developing solution to selectively remove the photoresist film 85, and a developing process S127 for forming a resist pattern is performed.
In the development step S127, regions exposed to ultraviolet K through the opening 90a of the photomask 90, that is, excitation electrodes 13 and 14, extraction electrodes 19 and 20, and mount electrodes 16 and 17 (both refer to FIG. 1). The photoresist film 85 corresponding to the region where each electrode is not formed is removed.

(Metal film etching step S129)
Next, the electrode metal film 84 is etched using the resist pattern as a mask, and a metal film etching step S129 for forming each electrode is performed. In this step, the electrode metal film 84 masked with the resist pattern is left, and the electrode metal film 84 not masked with the resist pattern is selectively removed. Through the metal film etching step S129, the excitation electrodes 13 and 14, the extraction electrodes 19 and 20 and the mount electrodes 16 and 17 of the piezoelectric vibrating piece 4 are formed (see FIG. 1).
The excitation electrodes 13 and 14 and the extraction electrodes 19 and 20 shown in FIG. 1 are formed of a single layer film of a chromium base film 84a by peeling off the gold finish film 84b. Further, the mount electrodes 16 and 17 are formed of a laminated film of a chromium base film 84a and a gold finish film 84b by leaving a chromium base film 84a and a gold finish film 84b.
When the metal film etching step S129 is finished, the electrode forming step S120 is finished.

(Frequency adjustment step S130)
Next, a weight metal film 21 (for example, silver, gold, or the like) composed of a frequency adjustment coarse adjustment film 21a and a fine adjustment film 21b is formed at the tips of the pair of vibrating arm portions 10 and 11 (see FIG. 1). Then, a frequency adjustment step S130 for roughly adjusting the resonance frequency is performed on all the vibrating arm portions 10 and 11 formed on the quartz wafer W. The coarse adjustment films 21a and 21b of the weight metal film 21 are irradiated with laser light to evaporate a part thereof and change the weight. The fine adjustment for adjusting the resonance frequency with higher accuracy is performed in the state of the piezoelectric vibrator 30 (see FIG. 15). Above, frequency adjustment process S130 is complete | finished.

(Smallization step S140)
Finally, the vibration piece outer shape portion 4a (see FIG. 14) is cut from the quartz wafer W, and a fragmentation step S140 is performed in which the plurality of piezoelectric vibration pieces 4 are fragmented. As a result, a plurality of tuning-fork type piezoelectric vibrating reeds 4 can be manufactured from one crystal wafer W at a time. At this time, the manufacturing process of the piezoelectric vibrating reed 4 is completed, and a plurality of piezoelectric vibrating reeds 4 can be obtained.

(effect)
According to the present embodiment, by forming the through holes 8 and 9 in the vibrating arm portions 10 and 11, the inner side surfaces 8 a to 8 d that connect the + Z side surface F and the −Z side surface S of the vibrating arm portions 10 and 11, 9a to 9d are formed. Therefore, by applying a metal material and a photoresist material from the + Z side of the quartz wafer, the electrode metal film 84 and the photoresist are formed on the inner side surfaces 8a, 8c, 9a, and 9c along the Y direction of the vibrating arm portions 10 and 11. The film 85 can be formed, and the excitation electrodes 13 and 14 can be formed.
Further, the mount electrodes 16 and 17 and the extraction electrodes 19 and 20 are formed only on the + Z side surface F of the base portion 12 and are not formed on the −Z side surface S. Therefore, by applying a metal material and a photoresist material from the + Z side of the crystal wafer W, the electrode metal film 84 and the photoresist film 85 can be formed on the + Z side surface F of the base portion 12, and the mount electrodes 16, 17 and the lead electrodes are extracted. Electrodes 19 and 20 can be formed.
Further, since the photoresist film 85 is not formed on the −Z side surface S of the quartz wafer W in the electrode forming step S120, the photoresist film 85 may be exposed only from the + Z side of the quartz wafer W. Accordingly, it is not necessary to introduce an expensive double-side exposure apparatus or prepare a pair of photomasks and dispose them on both the + Z side surface F and the −Z side surface S of the quartz wafer W as in the prior art. .
As described above, in the electrode forming step S120, each electrode can be formed by forming the electrode metal film 84, forming the photoresist film 85, and exposing only from the + Z side of the crystal wafer W. Therefore, the present embodiment is compared with the prior art in which the electrodes are formed by forming the electrode metal film 84, forming the photoresist film 85 and exposing from both the + Z side and the −Z side of the quartz wafer W. Thus, the man-hours can be reduced and the manufacturing apparatus can be simplified, and the low-cost piezoelectric vibrating reed 4 can be formed.

  Further, according to the present embodiment, the excitation electrodes 13 and 14 include the inner side surfaces 8a, 8c, 9a and 9c of the through holes 8 and 9, the + X side surfaces 10a and 11a of the vibrating arm portions 10 and 11, and the vibrating arm portion 10 and 11 are formed over the entire Z direction on the −X side surfaces 10b and 11b. Accordingly, an electric field can be formed in the direction along the X direction of the vibrating arm portions 10 and 11 over the entire Z direction of the vibrating arm portions 10 and 11. Therefore, since the vibrating arm portions 10 and 11 can be vibrated efficiently, the piezoelectric vibrating reed 4 with less loss can be formed.

According to the present embodiment, since the wafer etching step S114 is performed from both the + Z side and the −Z side of the quartz wafer W, the outer shape can be formed uniformly along the thickness direction of the resonator element outer portion 4a. Therefore, since the pair of vibrating arm portions 10 and 11 can be formed with high accuracy, the piezoelectric vibrating piece 4 having stable frequency characteristics can be formed.
In addition, according to the present embodiment, the vibrating piece outer shape portion 4a and the through holes 8 and 9 of the piezoelectric vibrating piece 4 can be simultaneously formed in one wafer etching step S114. Therefore, the wafer etching step S114 can be simplified as compared with the conventional technique in which the groove portions 205 and 206 (see FIG. 22) are formed by half-etching after the vibration piece outer portion 4a of the piezoelectric vibration piece 4 is etched.

  According to the present embodiment, in the electrode formation step S120, the metal film formation step S121, the photoresist film formation step S123, and the exposure step S125 are performed only from the + Z side of the crystal wafer W. Compared to the prior art in which the metal film forming step S121, the photoresist film forming step S123, and the exposure step S125 are performed from both sides on the side and the −Z side, man-hours can be reduced and the manufacturing apparatus can be simplified. Therefore, the low-cost piezoelectric vibrating piece 4 can be formed.

(Piezoelectric vibrator)
Next, a piezoelectric vibrator using the piezoelectric vibrating piece 4 of the present embodiment will be described.
FIG. 15 is an external perspective view of the piezoelectric vibrator 30.
FIG. 16 is an internal configuration diagram of the piezoelectric vibrator 30 and is a plan view in a state where the lid substrate 32 is removed.
17 is a cross-sectional view taken along the line CC of FIG.
18 is an exploded perspective view of the piezoelectric vibrator 30 shown in FIG.
In the following description, the bonding surface of the base substrate 31 to the lid substrate 32 is a first surface U, and the outer surface of the base substrate 31 is a second surface L.

  As shown in FIG. 15, the piezoelectric vibrator 30 of this embodiment includes a package in which a base substrate 31 and a lid substrate 32 are anodically bonded via a bonding film 37, and a cavity C of the package as shown in FIG. This is a surface-mount type piezoelectric vibrator 30 having a piezoelectric vibrating piece 4 housed therein.

The base substrate 31 and the lid substrate 32 are anodic bondable substrates made of a glass material such as soda lime glass, and are formed in a substantially plate shape. A cavity recess 32 a for accommodating the piezoelectric vibrating reed 4 is formed on the side of the lid substrate 32 that is bonded to the base substrate 31.
On the lid substrate 32, a bonding film 37 for anodic bonding is formed on the entire bonding surface side with the base substrate 31. The bonding film 37 of this embodiment is formed of a silicon film, and the bonding film 37 and the base substrate 31 are anodically bonded, and the cavity C is vacuum-sealed.

  As shown in FIG. 17, the piezoelectric vibrator 30 includes through electrodes 35 and 36 that penetrate the base substrate 31 in the thickness direction and conduct the inside of the cavity C and the outside of the piezoelectric vibrator 30. The through electrodes 35 and 36 are disposed in electrode holes 33 and 34 that penetrate the base substrate 31. The electrode holes 33 and 34 are formed so as to be accommodated in the cavity C when the piezoelectric vibrator 30 is formed.

  The through electrodes 35 and 36 are formed, for example, by inserting a metal pin (not shown) into the electrode holes 33 and 34 and then filling and baking a glass frit between the electrode holes 33 and 34 and the metal pin. Thus, since the electrode holes 33 and 34 can be completely closed by the metal pin and the glass frit, the routing electrodes 38 and 39 and the external electrodes 40 and 41, which will be described later, are electrically connected while maintaining the airtightness in the cavity C. I have a role to let you.

  As shown in FIG. 18, a pair of routing electrodes 38 and 39 are patterned on the first surface U side of the base substrate 31. Of the pair of lead-out electrodes 38 and 39, one lead-out electrode 38 is formed so as to be located immediately above one through-electrode 35. Further, the other lead electrode 39 is routed from the position adjacent to the one lead electrode 38 to the tip side along the vibrating arm portions 10 and 11, and then positioned directly above the other through electrode 36. Is formed.

A bump B made of gold or the like is formed on each of the pair of lead electrodes 38 and 39, and the pair of mount electrodes 16 and 17 (see FIG. 9) of the piezoelectric vibrating reed 4 are mounted using the bump B. Has been. Specifically, mounting is performed by so-called flip chip bonding in which the mount electrodes 16 and 17 are brought into contact with the bumps B and ultrasonic bonding is performed by applying ultrasonic vibration to the piezoelectric vibrating piece 4 while heating the bonding interface.
Here, as shown in FIG. 1, the mount electrodes 16 and 17 are formed only on the + Z side surface F of the base portion 12 of the piezoelectric vibrating piece 4, and as shown in FIG. 2, the mount electrodes 16 and 17 are formed on the base portion 12 of the piezoelectric vibrating piece 4. -Z is not formed on the side surface S. Therefore, the piezoelectric vibrating reed 4 is mounted with the + Z side surface F of the piezoelectric vibrating reed 4 on which the mount electrodes 16 and 17 are formed facing the first surface U of the base substrate 31 (see FIG. 17).
As a result, as shown in FIG. 16, one mount electrode 16 (see FIG. 1) of the piezoelectric vibrating reed 4 is electrically connected to one through electrode 35 via one routing electrode 38, and the other mount electrode 17 is Then, the other through electrode 36 is conducted through the other lead-out electrode 39.

  A pair of external electrodes 40 and 41 is formed on the second surface L of the base substrate 31. The pair of external electrodes 40 and 41 are formed at both ends of the base substrate 31 in the longitudinal direction (left and right direction in FIG. 17), and are electrically connected to the pair of through electrodes 35 and 36, respectively.

  When the piezoelectric vibrator 30 configured as described above is operated, a predetermined drive voltage is applied to the external electrodes 40 and 41 formed on the base substrate 31. As a result, a voltage can be applied to the first excitation electrode 13 and the second excitation electrode 14 (see FIG. 1) of the piezoelectric vibrating reed 4, so that the pair of vibrating arm portions 10 and 11 are brought closer to and away from each other. Can be vibrated at a predetermined frequency. The piezoelectric vibrator 30 can be used as a time source, a control signal timing source, a reference signal source, and the like by using the vibration of the pair of vibrating arm portions 10 and 11.

(effect)
According to the present embodiment, the low-cost piezoelectric vibrator 30 can be provided because the low-cost piezoelectric vibrating reed 4 that can reduce the man-hour of the electrode forming step S120 and simplify the manufacturing apparatus is provided.

(Oscillator)
Next, an embodiment of an oscillator according to the present invention will be described with reference to FIG.
As shown in FIG. 19, the oscillator 110 according to the present embodiment is configured by configuring the piezoelectric vibrator 30 as an oscillator electrically connected to the integrated circuit 111. The oscillator 110 includes a substrate 113 on which an electronic element component 112 such as a capacitor is mounted. An integrated circuit 111 for an oscillator is mounted on the substrate 113, and a piezoelectric vibrating piece of the piezoelectric vibrator 30 is mounted in the vicinity of the integrated circuit 111. The electronic element component 112, the integrated circuit 111, and the piezoelectric vibrator 30 are electrically connected by a wiring pattern (not shown). Each component is molded with a resin (not shown).

In the oscillator 110 configured as described above, when a voltage is applied to the piezoelectric vibrator 30, the piezoelectric vibrating piece in the piezoelectric vibrator 30 vibrates. This vibration is converted into an electric signal by the piezoelectric characteristics of the piezoelectric vibrating piece and input to the integrated circuit 111 as an electric signal. The input electrical signal is subjected to various processes by the integrated circuit 111 and output as a frequency signal. Thereby, the piezoelectric vibrator 30 functions as an oscillator.
In addition, by selectively setting the configuration of the integrated circuit 111, for example, an RTC (real-time clock) module or the like as required, the operation date and time of the device or external device in addition to a single-function oscillator for a clock, etc. A function for controlling the time, providing a time, a calendar, and the like can be added.

  According to the oscillator 110 of this embodiment, since the low-cost piezoelectric vibrator 30 is provided, the low-cost oscillator 110 can be manufactured.

(Electronics)
Next, an embodiment of an electronic apparatus according to the present invention will be described with reference to FIG. Note that a portable information device 120 having the above-described piezoelectric vibrator 30 will be described as an example of the electronic device.
First, the portable information device 120 of this embodiment is represented by, for example, a mobile phone, and is a development and improvement of a wrist watch in the prior art. The appearance is similar to that of a wristwatch, and a liquid crystal display is arranged in a portion corresponding to a dial so that the current time and the like can be displayed on this screen. Further, when used as a communication device, it is possible to perform communication similar to that of a conventional mobile phone by using a speaker and a microphone that are removed from the wrist and incorporated in the inner portion of the band. However, it is much smaller and lighter than conventional mobile phones.

  Next, the configuration of the portable information device 120 of this embodiment will be described. As shown in FIG. 20, the portable information device 120 includes a piezoelectric vibrator 30 and a power supply unit 121 for supplying power. The power supply unit 121 is made of, for example, a lithium secondary battery. The power supply unit 121 includes a control unit 122 that performs various controls, a clock unit 123 that counts time, a communication unit 124 that communicates with the outside, a display unit 125 that displays various information, and the like. A voltage detection unit 126 that detects the voltage of the functional unit is connected in parallel. Power is supplied to each functional unit by the power supply unit 121.

  The control unit 122 controls each function unit to control operation of the entire system such as transmission and reception of audio data, measurement and display of the current time, and the like. The control unit 122 includes a ROM in which a program is written in advance, a CPU that reads and executes the program written in the ROM, and a RAM that is used as a work area for the CPU.

  The timer unit 123 includes an integrated circuit that includes an oscillation circuit, a register circuit, a counter circuit, an interface circuit, and the like, and the piezoelectric vibrator 30. When a voltage is applied to the piezoelectric vibrator 30, the piezoelectric vibrating piece vibrates, and the vibration is converted into an electric signal by the piezoelectric characteristics of the crystal and input to the oscillation circuit as an electric signal. The output of the oscillation circuit is binarized and counted by a register circuit and a counter circuit. Then, signals are transmitted to and received from the control unit 122 through the interface circuit, and the current time, current date, calendar information, and the like are displayed on the display unit 125.

The communication unit 124 has functions similar to those of a conventional mobile phone, and includes a radio unit 127, a voice processing unit 128, a switching unit 129, an amplification unit 130, a voice input / output unit 131, a telephone number input unit 132, a ring tone generation unit. 133 and a call control memory unit 134.
The radio unit 127 exchanges various data such as audio data with the base station via the antenna 135. The audio processing unit 128 encodes and decodes the audio signal input from the radio unit 127 or the amplification unit 130. The amplifying unit 130 amplifies the signal input from the audio processing unit 128 or the audio input / output unit 131 to a predetermined level. The voice input / output unit 131 includes a speaker, a microphone, and the like, and amplifies a ringtone and a received voice or collects a voice.

In addition, the ring tone generator 133 generates a ring tone in response to a call from the base station. The switching unit 129 switches the amplifying unit 130 connected to the voice processing unit 128 to the ringing tone generating unit 133 only when an incoming call is received, so that the ringing tone generated by the ringing tone generating unit 133 passes through the amplifying unit 130. To the audio input / output unit 131.
Note that the call control memory unit 134 stores a program related to incoming / outgoing call control of communication. The telephone number input unit 132 includes, for example, number keys from 0 to 9 and other keys. By pressing these number keys and the like, a telephone number of a call destination is input.

  The voltage detection unit 126 detects the voltage drop and notifies the control unit 122 when the voltage applied to each functional unit such as the control unit 122 by the power supply unit 121 falls below a predetermined value. . The predetermined voltage value at this time is a value set in advance as a minimum voltage necessary to stably operate the communication unit 124, and is, for example, about 3V. Upon receiving the voltage drop notification from the voltage detection unit 126, the control unit 122 prohibits the operations of the radio unit 127, the voice processing unit 128, the switching unit 129, and the ring tone generation unit 133. In particular, it is essential to stop the operation of the wireless unit 127 with high power consumption. Further, the display unit 125 displays that the communication unit 124 has become unusable due to insufficient battery power.

That is, the operation of the communication unit 124 can be prohibited by the voltage detection unit 126 and the control unit 122, and that effect can be displayed on the display unit 125. This display may be a text message, but as a more intuitive display, a x (X) mark may be attached to the telephone icon displayed at the top of the display surface of the display unit 125.
In addition, the function of the communication part 124 can be stopped more reliably by providing the power supply cutoff part 136 that can selectively cut off the power of the part related to the function of the communication part 124.

  According to the portable information device 120 of the present embodiment, since the low-cost piezoelectric vibrator 30 is provided, the low-cost portable information device 120 can be manufactured.

(Radio watch)
Next, an embodiment of a radio timepiece according to the present invention will be described with reference to FIG.
As shown in FIG. 21, the radio-controlled timepiece 140 according to the present embodiment includes a piezoelectric vibrator 30 electrically connected to a filter unit 141. The radio-controlled timepiece 140 receives a standard radio wave including timepiece information and is accurate. It is a clock with a function of automatically correcting and displaying the correct time.
In Japan, there are transmitting stations (transmitting stations) that transmit standard radio waves in Fukushima Prefecture (40 kHz) and Saga Prefecture (60 kHz), each transmitting standard radio waves. Long waves such as 40 kHz or 60 kHz have both the property of propagating the ground surface and the property of propagating while reflecting the ionosphere and the ground surface, so the propagation range is wide, and the above two transmitting stations cover all of Japan. doing.

Hereinafter, the functional configuration of the radio timepiece 140 will be described in detail.
The antenna 142 receives a long standard wave of 40 kHz or 60 kHz. The long-wave standard radio wave is obtained by subjecting time information called a time code to AM modulation on a 40 kHz or 60 kHz carrier wave. The received long standard wave is amplified by the amplifier 143 and filtered and tuned by the filter unit 141 having the plurality of piezoelectric vibrators 30.
The piezoelectric vibrator 30 in this embodiment includes crystal vibrator portions 148 and 149 having resonance frequencies of 40 kHz and 60 kHz, which are the same as the carrier frequency.

Further, the filtered signal having a predetermined frequency is detected and demodulated by the detection and rectification circuit 144.
Subsequently, the time code is taken out via the waveform shaping circuit 145 and counted by the CPU 146. The CPU 146 reads information such as the current year, accumulated date, day of the week, and time. The read information is reflected in the RTC 148, and accurate time information is displayed.
Since the carrier wave is 40 kHz or 60 kHz, the crystal vibrator portions 148 and 149 are preferably vibrators having the tuning fork type structure described above.

  In addition, although the above-mentioned description was shown in the example in Japan, the frequency of the long standard wave is different overseas. For example, in Germany, a standard radio wave of 77.5 KHz is used. Therefore, when the radio timepiece 140 that can be used overseas is incorporated in a portable device, the piezoelectric vibrator 30 having a frequency different from that in Japan is required.

  According to the radio timepiece 140 of this embodiment, since the low-cost piezoelectric vibrator 30 is provided, the low-cost radio timepiece 140 can be manufactured.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  In the present embodiment and the modified example of the present embodiment, the through holes 8 and 9 formed in the vibrating arm portions 10 and 11 are formed in a substantially rectangular shape in a plan view in the Z direction having a certain width in the X direction. The shape of the through holes 8 and 9 is not limited to this. For example, the through-holes 8 and 9 are substantially in the Z-direction plan view, and the width in the X direction gradually decreases from the + Y side (the distal end side of the vibrating arm portion) to the −Y side (the proximal end side of the vibrating arm portion). It may be formed in a shape. Thus, by changing the shape of the through holes 8 and 9, the rigidity on the −Y side of the vibrating arm portions 10 and 11 can be arbitrarily set. Therefore, the drive level characteristic depending on the rigidity of the vibrating arm portions 10 and 11 can be set to a desired characteristic.

In the present embodiment, one through hole 8 and 9 is formed in each of the vibrating arm portions 10 and 11. In the modification of this embodiment, two through holes 8A and 8B and two through holes 9A and 9B are formed in the vibrating arm portions 10 and 11, respectively. However, the number of the through holes 8 and 9 is not limited to the embodiment and the modified example of the embodiment.
Moreover, in the modification of this embodiment, although the two through-holes 8 and 9 were formed in series along the Y direction, multiple pieces may be formed in parallel along the X direction, for example.
The rigidity of the vibrating arm portions 10 and 11 can be arbitrarily set by changing the number, the formation position, the arrangement, and the like of the through holes 8 and 9. Therefore, the drive level characteristic depending on the rigidity of the vibrating arm portions 10 and 11 can be set to a desired characteristic.

  In the present embodiment and the modification of the present embodiment, the piezoelectric vibrating reed 4 mounted on the surface-mount type piezoelectric vibrator 30 is described using the method for manufacturing the piezoelectric vibrating reed 4 of the present invention. For example, the piezoelectric vibrating piece manufacturing method of the present invention may be adopted for a piezoelectric vibrating piece mounted on a cylinder package type piezoelectric vibrator.

DESCRIPTION OF SYMBOLS 4 ... Piezoelectric vibrating piece 4a ... Vibrating piece outer part (piezoelectric plate) 8, 9 ... Through-hole 8a, 8c, 9a, 9c ... Inner side surface along longitudinal direction 10, 11, ... Vibration arm portion 10a, 10b, 11a, 11b ... Outer surface of vibration arm portion 12 ... Base portion 13, 14 ... Excitation electrode 16, 17 ... Mount electrode 19, 20 ... Extraction electrode 30. ··· Piezoelectric vibrator 74 ··· Metal film for mask 84 ··· Metal film for electrode 110 ··· Oscillator 120 ··· Portable information device (electronic device) 140 ··· Radio watch S110 · · · Outline forming step S112: Mask pattern forming step S114 ... Wafer etching step S120 ... Electrode forming step S121 ... Metal film forming step S123 ... Photoresist film forming step (photosensitive material film forming step) S125 ... Exposure process + Z side ... One side -Z side ... The other side

Claims (9)

A piezoelectric plate having a pair of vibrating arm portions arranged side by side and a base to which the pair of vibrating arm portions are connected;
An excitation electrode formed on the vibrating arm and vibrating the vibrating arm;
A mount electrode formed on the base and electrically connected to the outside;
An extraction electrode connecting the excitation electrode and the mount electrode;
A piezoelectric vibrating piece with
The vibrating arm portion is formed with a through-hole penetrating one side and the other side in the thickness direction of the piezoelectric plate and extending along the longitudinal direction of the vibrating arm portion,
The excitation electrode is formed on an inner surface along the longitudinal direction of the inner surface of the through hole and an outer surface of the vibrating arm portion facing the inner surface, and the mount electrode and the extraction electrode are formed on the base portion. The piezoelectric vibrating piece is formed on the main surface only on the one side. The piezoelectric vibrating piece according to claim 1,
The piezoelectric vibrating piece according to claim 1, wherein the excitation electrode is formed over the entire thickness direction of the vibrating arm portion. The piezoelectric vibrating piece according to claim 1 or 2,
A plurality of the through holes are formed in each of the vibrating arm portions, respectively. A method for manufacturing a piezoelectric vibrating piece according to any one of claims 1 to 3,
An outer shape forming step of forming the outer shape of the piezoelectric plate and the through hole from the piezoelectric wafer;
An electrode forming step of patterning a metal film for an electrode by a photolithography technique to form each electrode on the piezoelectric plate;
With
The electrode forming step includes
A metal film forming step of forming the electrode metal film on the surface of the piezoelectric plate;
A photosensitive material film forming step of forming a photosensitive material film on the metal film for electrodes;
An exposure step of exposing the photosensitive material film using a photomask in which a pattern corresponding to each electrode is formed;
Have
The method for manufacturing a piezoelectric vibrating piece, wherein the metal film forming step, the photosensitive material film forming step, and the exposure step are performed only from the one side of the piezoelectric plate. A method of manufacturing a piezoelectric vibrating piece according to claim 4,
The outer shape forming step includes
Forming a mask metal film on both main surfaces of the piezoelectric wafer, and forming a mask pattern of the piezoelectric plate from the mask metal film by a photolithography technique; and
A wafer etching step for etching the piezoelectric wafer from both sides of the one side and the other side of the piezoelectric wafer via the mask pattern;
A method for manufacturing a piezoelectric vibrating piece, comprising:   A piezoelectric vibrator according to claim 1, wherein the piezoelectric vibrating piece is housed in a cavity formed by a base substrate and a lid substrate.   An oscillator, wherein the piezoelectric vibrator according to claim 6 is electrically connected to an integrated circuit as an oscillator.   An electronic apparatus, wherein the piezoelectric vibrator according to claim 6 is electrically connected to a timer unit. A radio-controlled timepiece, wherein the piezoelectric vibrator according to claim 6 is electrically connected to a filter portion.

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