JP2013191981A - Piezoelectric vibrating piece, method for manufacturing piezoelectric vibrating piece, piezoelectric resonator, oscillator, electronic device, and radio-controlled timepiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric vibrating piece that has favorable vibration properties.SOLUTION: A piezoelectric vibrating piece 4 includes: a pair of vibrating arms 10 and 11 that are arranged side by side; a base to which the pair of vibrating arms 10 and 11 are connected; and a pair of excitation electrodes 13 and 14 that are formed on the vibrating arms 10 and 11 electrically independently of each other and that vibrate the vibrating arms 10 and 11. A first one of the excitation electrodes 13 and 14 is formed on side wall surfaces 5b of grooves 5 that are provided in main surfaces 4a of the vibrating arms 10 and 11. A second one of the excitation electrodes 13 and 14 is formed on side surfaces 4b of the vibrating arms 10 and 11 so as to sandwich the vibrating arms 10 and 11 with the first one of the excitation electrodes 13 and 14. A portion of each groove 5 positioned nearer to a bottom wall surface 5a relative to an opening 5c is at least partially wider than the opening 5c in a short width direction of the vibrating arms 10 and 11.

Description

  The present invention relates to a piezoelectric vibrating piece, a method of manufacturing a piezoelectric vibrating piece, a piezoelectric vibrator, an oscillator, 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. Various types of piezoelectric vibrators of this type are provided, and one of them is a piezoelectric vibrator in which a so-called tuning fork type piezoelectric vibrating piece is enclosed in a package. The piezoelectric vibrating reed is formed on the vibrating arm portion electrically and independently of the pair of vibrating arm portions arranged side by side, the base portion to which the pair of vibrating arm portions are connected, and vibrates the vibrating arm portion. A pair of excitation electrodes.

By the way, in recent years, with the downsizing of devices to be mounted, it is desired to further reduce the size of the piezoelectric vibrating piece while keeping the CI value (Crystal Impedance) of the piezoelectric vibrating piece low. Therefore, as the piezoelectric vibrating piece, for example, a configuration in which a groove is provided on the main surface of the vibrating arm as shown in Patent Document 1 below can be considered.
In this piezoelectric vibrating piece, one excitation electrode of the pair of excitation electrodes is formed on the side wall surface of the groove, and the other excitation electrode is formed on the side surface of the vibration arm portion and between the one excitation electrode and the vibrating arm. It is formed so as to sandwich the part. Thereby, both excitation electrodes can be brought close to each other with the vibrating arm portion interposed therebetween, and the CI value can be suppressed low.

JP 2008-29030 A

  Here, in the piezoelectric vibrating piece, it is conceivable that the CI value is further reduced by enlarging the groove portion in the width direction of the vibrating arm portion. However, in this case, since the opening of the groove is widened in the short width direction, a region (hereinafter referred to as a gap) between the opening edge of the groove and the side edge of the main surface on the main surface of the vibrating arm portion. The size along the short width direction of the region) is also reduced. As a result, for example, it becomes difficult to form both excitation electrodes at a certain interval on the inter-region, and both excitation electrodes are too close to each other and short-circuit, or the parallel capacitance C0 in the equivalent circuit of the piezoelectric vibrating piece is reduced. If it becomes unstable, the vibration characteristics of the piezoelectric vibrating piece may be affected.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a piezoelectric vibrating piece that can easily exhibit good vibration characteristics.

In order to solve the above problems, the present invention proposes the following means.
A piezoelectric vibrating piece according to the present invention is formed on the vibrating arm portion, a pair of vibrating arm portions arranged side by side, a base portion to which the pair of vibrating arm portions are connected, and electrically independent of each other, A pair of excitation electrodes that vibrate the vibration arm portion, and one of the pair of excitation electrodes is formed on a side wall surface of a groove portion provided on a main surface of the vibration arm portion, The excitation electrode is located on a side surface of the vibrating arm portion such that the vibrating arm portion is sandwiched between the excitation electrode portion and the one excitation electrode, and is located closer to the bottom wall surface than the opening portion in the groove portion. At least a part of the portion is wider in the width direction of the vibrating arm than the opening.

  According to the present invention, at least a part (hereinafter referred to as the wide width portion) of the groove portion located on the bottom wall surface side of the opening portion is wider in the short width direction than the opening portion of the groove portion. The side wall surface of the wide portion and the side surface of the vibrating arm portion are brought close to each other in the short width direction, and the interval between the two excitation electrodes formed so as to sandwich the vibrating arm portion between the side wall surface and the side surface is reduced. it can. Accordingly, it is possible to reduce the CI value while suppressing the opening of the groove portion from being widened in the short width direction, and it is possible to make the piezoelectric vibrating piece easily exhibit good vibration characteristics.

  Moreover, the said groove part may be gradually widened in the said width direction as it goes to the bottom wall surface side from the opening part side.

  In this case, since the groove portion is gradually widened in the short width direction from the opening side toward the bottom wall surface side, it is possible to ensure a good strength of the vibrating arm portion, and to the piezoelectric vibrating piece. It is possible to easily exhibit better vibration characteristics.

  The method for manufacturing a piezoelectric vibrating piece according to the present invention is a method for manufacturing a piezoelectric vibrating piece in which the piezoelectric vibrating piece is formed from a wafer, and includes a groove forming step of forming the groove on the wafer, The groove forming step includes a dry etching step of etching the wafer by dry etching after forming a protective film on the wafer, and the dry etching step varies the supply amount of etching gas for etching the wafer. It is characterized by being implemented multiple times.

  According to the present invention, since the dry etching process is performed a plurality of times with different supply amounts of the etching gas, the amount of etching in the width direction of the wafer is accurately varied for each dry etching process, and the groove portion It is possible to easily adjust the width in the short width direction, and the groove can be formed with high accuracy.

  Moreover, the said groove part formation process may have the wet etching process of etching the said wafer by wet etching before the said dry etching process.

In this case, since the groove forming step includes the wet etching step, the time required for etching can be shortened, and productivity can be improved.
Moreover, since the wet etching process is performed before the dry etching process, the groove can be reliably formed with high accuracy. That is, when the wet etching process is performed after the dry etching process, the portion of the groove formed by the dry etching process is also etched by the wet etching process, making it difficult to form the groove with high accuracy. There is a risk.

  The piezoelectric vibrator according to the present invention includes the piezoelectric vibrating piece.

  According to the present invention, since the piezoelectric vibrating piece that can easily exhibit good vibration characteristics is provided, a piezoelectric vibrator with high efficiency and low power consumption 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 present invention, it is possible to provide a high-performance oscillator, electronic device, and radio timepiece with high efficiency and low power consumption.

  According to the present invention, it is possible to easily exhibit good vibration characteristics.

It is a top view of a piezoelectric vibrating piece. It is sectional drawing along the AA line of FIG. It is a flowchart which shows the manufacturing method of a piezoelectric vibrating piece. It is sectional drawing explaining a groove part formation process. It is sectional drawing explaining a groove part formation process. It is sectional drawing explaining a groove part formation process. It is sectional drawing explaining a groove part formation process. It is a graph which shows an analysis result. 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 in the CC line of FIG. FIG. 10 is an exploded perspective view of the piezoelectric vibrator shown in FIG. 9. 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 sectional drawing which shows the modification of a piezoelectric vibrating piece. It is sectional drawing which shows the modification of a piezoelectric vibrating piece. It is sectional drawing which shows the modification of a piezoelectric vibrating piece.

(Piezoelectric vibrating piece)
Hereinafter, the piezoelectric vibrating piece of the embodiment will be described with reference to the drawings.
FIG. 1 is a plan view of the piezoelectric vibrating piece 4.
FIG. 2 is a cross-sectional view of the groove 5 taken along the line AA in FIG.
In the following, the width direction in which the vibrating arm portions 10 and 11 are arranged is the X direction (short width direction), the central axis in the X direction is O, the inner side of the piezoelectric vibrating piece 4 is the −X side, and the outer side. Is described as the + X side. In the description, the longitudinal direction of the piezoelectric vibrating reed 4 is defined as the Y direction (longitudinal width direction), the base end side is defined as -Y side, and the distal end side is defined as + Y side. Further, the thickness direction of the piezoelectric vibrating piece 4 is described as the Z direction.

  As shown in FIG. 1, the piezoelectric vibrating reed 4 is a tuning fork type formed from a piezoelectric material such as quartz, lithium tantalate, or lithium niobate. The piezoelectric vibrating reed 4 includes a pair of vibrating arm portions 10 and 11 (first vibrating arm portion 10 and second vibrating arm portion 11) arranged in parallel, and the −Y side of the pair of vibrating arm portions 10 and 11. A piezoelectric plate 15 having a base portion 12 that integrally fixes the base plate 12 is provided. The piezoelectric vibrating reed 4 vibrates in the X direction so that the vibrating arm portions 10 and 11 approach and separate from each other when a predetermined voltage is applied.

The pair of vibrating arm portions 10 and 11 extends in the Y direction along the central axis O, and is formed so as to be substantially parallel to the X direction. Groove portions 5 extending along the Y direction of the vibrating arm portions 10 and 11 are provided on both main surfaces 4 a of the vibrating arm portions 10 and 11. All the groove portions 5 have the same shape.
As shown in FIG. 2, at least a part of the groove portion 5 located on the bottom wall surface 5 a side with respect to the opening 5 c is wider in the X direction than the opening 5 c of the groove 5. In the present embodiment, the groove 5 is gradually widened in the X direction as it goes from the opening 5c side to the bottom wall surface 5a side. The groove 5 extends to both the + X side and the −X side. In a cross-sectional view, the side wall surface 5b of the groove portion 5 gradually extends linearly toward the + X side or the -X side from the opening 5c side toward the bottom wall surface 5a side, and extends in both the X direction and the Z direction. Inclined. The cross-sectional shape of the groove 5 is symmetric in the X direction, and is an isosceles trapezoid in the illustrated example. The groove portion 5 has the same shape over the entire length in the Y direction.

  Here, as shown in FIG. 1, the piezoelectric vibrating reed 4 includes a first excitation electrode 13 and a second excitation electrode that are formed on the pair of vibrating arm portions 10 and 11 and vibrate the pair of vibrating arm portions 10 and 11. 14 (a pair of excitation electrodes), a first mount electrode 16 and a second mount electrode 17 electrically connected to the first excitation electrode 13 and the second excitation electrode 14, respectively, 14 and mount electrodes 16 and 17, and lead electrodes 19 and 20 that electrically connect the mount electrodes 16 and 17, respectively.

The mount electrodes 16 and 17 and the extraction electrodes 19 and 20 are formed on the base 12. The mount electrodes 16 and 17 are formed so as to sandwich the central axis O.
When a voltage is applied, the excitation electrodes 13 and 14 cause the pair of vibrating arm portions 10 and 11 to vibrate at a predetermined resonance frequency in the X direction so as to approach or separate from each other. The pair of excitation electrodes 13 and 14 are formed by being electrically separated from the surfaces of the pair of vibrating arm portions 10 and 11 and patterned in an independent state.

  As shown in FIGS. 1 and 2, the first excitation electrode 13 is formed on the side surface 4 b of the second vibrating arm portion 11. The first excitation electrode 13 is formed on both side surfaces 4 b of the second vibrating arm portion 11. The first excitation electrode 13 is formed in a region where the position in the Y direction overlaps the groove portion 5 on the side surface 4 b of the second vibrating arm portion 11. The first excitation electrode 13 extends from the side surface 4b of the second vibrating arm portion 11 to the main surface 4a of the second vibrating arm portion 11 between the opening edge of the groove portion 5 and the side edge of the main surface 4a. It wraps around the area 8 (hereinafter referred to as the inter-area).

  The first excitation electrode 13 is also formed on the main surface 4 a of the first vibrating arm portion 10. The first excitation electrode 13 is formed on both main surfaces 4 a of the first vibrating arm portion 10. The first excitation electrode 13 is formed in a region including the groove portion 5 on the main surface 4 a of the first vibrating arm portion 10. The first excitation electrode 13 is formed over the entire surface of the side wall surface 5b and the bottom wall surface 5a of the groove 5. The first excitation electrode 13 extends from the side wall surface 5 b of the groove portion 5 to a region 8 in the main surface 4 a of the first vibrating arm portion 10.

  The second excitation electrode 14 is formed on the side surface 4 b of the first vibrating arm portion 10. The second excitation electrode 14 is formed on both side surfaces 4 b of the first vibrating arm portion 10. The second excitation electrode 14 is formed in a region where the position in the Y direction overlaps the groove portion 5 on the side surface 4 b of the first vibrating arm portion 10. The second excitation electrode 14 extends from the side surface 4 b of the first vibrating arm portion 10 to the intermediate region 8 in the main surface 4 a of the first vibrating arm portion 10.

  The second excitation electrode 14 is also formed on the main surface 4 a of the second vibrating arm portion 11. The second excitation electrode 14 is formed on both main surfaces 4 a of the second vibrating arm portion 11. The second excitation electrode 14 is formed in a region including the groove portion 5 on the main surface 4 a of the second vibrating arm portion 11. The second excitation electrode 14 is formed over the entire side wall surface 5b and bottom wall surface 5a of the groove 5. The second excitation electrode 14 extends from the side wall surface 5 b of the groove portion 5 to the intermediate region 8 in the main surface 4 a of the second vibrating arm portion 11.

As described above, in the first vibrating arm portion 10, of the pair of exciting electrodes 13 and 14, the first exciting electrode 13 is formed on the side wall surface 5 b of the groove portion 5, and the second exciting electrode 14 is the vibrating arm. The vibration arm portion 10 is formed on the side surface 4 b of the portion 10 so as to sandwich the first excitation electrode 13.
In the second vibrating arm portion 11, the second exciting electrode 14 of the pair of exciting electrodes 13 and 14 is formed on the side wall surface 5 b of the groove portion 5, and the first exciting electrode 13 is formed on the vibrating arm portion 11. The vibration arm portion 11 is sandwiched between the second excitation electrode 14 and the side surface 4b.
In both vibrating arm portions 10 and 11, the pair of excitation electrodes 13 and 14 are divided on the space 8, and the distance between the excitation electrodes 13 and 14 is stably secured to a constant size. ing.

  Each electrode described above is formed in a film shape. Here, each electrode may have a single layer structure or a laminated structure having an underlayer and a finishing layer. For example, each electrode may be formed as a laminated film of chromium and gold, a chromium film having good adhesion to crystal as a base layer, and then a gold thin film as a finishing layer on the surface. Good. Further, after depositing chromium and nichrome as a base layer, a gold thin film may be further deposited on the surface as a finishing layer. Further, while the mount electrodes 16 and 17 have a laminated structure, the lead-out electrodes 19 and 20 and the excitation electrodes 13 and 14 are formed of a single layer film with chromium of the same material as the base layer of the mount electrodes 16 and 17. May be. Furthermore, each electrode may be formed of, for example, nickel, aluminum, titanium, or the like.

  A weight metal film 21 composed of a coarse adjustment film 21a and a fine adjustment film 21b for adjusting (frequency adjustment) so as to vibrate within a predetermined frequency range is formed at the distal ends of the vibrating arms 10 and 11. Yes. 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.

(Method for manufacturing piezoelectric vibrating piece)
FIG. 3 is a flowchart showing a method for manufacturing the piezoelectric vibrating piece.
4 to 7 are sectional views for explaining the groove forming step.
Next, a method for manufacturing the above-described piezoelectric vibrating piece will be described. Hereinafter, a case where the piezoelectric vibrating piece 4 is formed from the wafer 40 will be described.
First, a raw quartz Lambert is sliced at a predetermined angle to obtain a wafer 40 having a constant thickness. Next, after lapping and roughing the wafer 40, the work-affected layer is removed by etching, and thereafter, mirror finishing such as polishing is performed to obtain a predetermined thickness (S110).

  Next, an outer shape forming step (S120) for forming the outer shapes of the plurality of piezoelectric plates 15 on the wafer 40 is executed. In this step, for example, first, a resist is formed in a region where the piezoelectric plate 15 is to be formed on the wafer 40, and then etching is performed from both surfaces of the wafer 40 to selectively remove regions where the resist is not formed. Run with.

Next, a groove portion forming step (S140) for forming the groove portions 5 on both main surfaces 4a of the vibrating arm portions (wafers) 10 and 11 is executed.
In the groove forming step, first, as shown in FIG. 4, a resist forming step is performed in which a resist R is formed in a region avoiding a region where the groove 5 is to be formed.
As shown in FIGS. 5 and 6, after forming the protective film M on the vibrating arm portions 10 and 11, a dry etching process is performed in which the vibrating arm portions 10 and 11 are etched by dry etching. At this time, in a state where the wafer 40 is disposed in the etching chamber S, the protective film M is formed in the region to be formed by introducing a gas for forming the protective film into the etching chamber S, for example, and then the etching chamber. An etching gas for etching the wafer 40 is introduced into S to etch the region to be formed.

Here, in this embodiment, as shown in FIG. 7, the dry etching process is performed a plurality of times with different supply amounts of the etching gas. The supply amount of the etching gas can be adjusted, for example, by changing the amount of etching gas introduced into the etching chamber S per unit time or the time for introducing the etching gas into the etching chamber S.
In the dry etching process, the etching amount in the X direction of the groove portion 5 can be adjusted according to the supply amount of the etching gas. In this embodiment, the etching gas supply amount is increased each time the dry etching process is repeated. Thereby, the groove part 5 will be formed.

Next, an electrode forming step (for example, patterning the electrode film on the plurality of piezoelectric plates 15 by sputtering or the like to form the excitation electrodes 13, 14, mount electrodes 16, 17, and extraction electrodes 19, 20, respectively) S150) is executed. Further, a weight metal film forming step (S160) for forming the weight metal film 21 at the tips of the pair of vibrating arm portions 10 and 11 is executed.
In the present embodiment, the excitation electrodes 13 and 14, the extraction electrodes 19 and 20, the electrode portions of the mount electrodes 16 and 17, and the weight metal film 21 are formed in separate steps, but the present invention is not limited thereto. Instead, they may be formed collectively in the same process.

  Next, a coarse adjustment step (S170) for coarsely adjusting the frequency is performed on all the vibrating arm portions 10 and 11 formed on the wafer 40. At this time, for example, the frequencies of all the vibrating arm portions 10 and 11 formed on the wafer 40 are measured together, and the trimming amount is calculated according to the difference between the measured frequency and a predetermined target frequency. Then, the coarse adjustment film 21a of the weight metal film 21 is irradiated with laser light to partially evaporate, and the coarse adjustment film 21a is removed (trimmed) according to the trimming amount. Note that fine adjustment for adjusting the resonance frequency with higher accuracy is performed after the piezoelectric vibrating reed 4 is mounted, for example.

Next, a cutting step (S180) is performed in which the connecting portion connecting the wafer 40 and the piezoelectric plate 15 is cut to separate the plurality of piezoelectric plates 15 from the wafer 40 into individual pieces.
As described above, a plurality of tuning-fork type piezoelectric vibrating reeds 4 are manufactured from one wafer 40 at a time.

As described above, according to the piezoelectric vibrating reed 4 according to the present embodiment, at least a part of the groove 5 located on the bottom wall surface 5a side with respect to the opening 5c (hereinafter referred to as the wide width portion) is the groove 5. Since the opening 5c is wider in the X direction, the side wall surface 5b of the wide portion and the side surface 4b of the vibrating arms 10 and 11 are brought closer to the X direction, and the side wall surface 5b and the side surface 4b vibrate. The interval between the two excitation electrodes 13 and 14 formed so as to sandwich the arm portions 10 and 11 can be reduced. Accordingly, it is possible to reduce the CI value while suppressing the opening 5c of the groove 5 from being widened in the X direction, and it is possible to make the piezoelectric vibrating piece 4 easily exhibit good vibration characteristics.
Further, since the groove portion 5 is gradually widened in the X direction as it goes from the opening 5c side to the bottom wall surface 5a side, the strength of the vibrating arm portions 10 and 11 can be secured well, and the piezoelectric vibrating piece 4 can be made to exhibit better vibration characteristics.

  In addition, according to the method for manufacturing the piezoelectric vibrating reed 4 according to the present embodiment, the dry etching process is performed a plurality of times with different supply amounts of the etching gas, so that the vibrating arm portions 10 and 11 are provided for each dry etching process. Therefore, it is possible to easily adjust the width of the groove portion 5 in the X direction, so that the groove portion 5 can be formed with high accuracy.

FIG. 8 is a graph showing the analysis results.
As shown in FIG. 8, in the piezoelectric vibrating piece 4, the size TW1 along the X direction in the opening 5c of the groove 5 is made constant at 42 μm, and the size TW2 along the X direction on the bottom wall surface 5a of the groove 5 is provided. As a result of analyzing the CI values for the configurations having different values, it was confirmed that the larger the TW2, the smaller the CI value with linearity.

(Piezoelectric vibrator)
Next, the piezoelectric vibrator 1 will be described as a package 9 including the piezoelectric vibrating reed 4 manufactured by the manufacturing method described above.
FIG. 9 is an external perspective view of the piezoelectric vibrator 1.
FIG. 10 is an internal configuration diagram of the piezoelectric vibrator 1 and is a plan view showing a state in which the lid substrate 3 is removed.
11 is a cross-sectional view taken along the line CC of FIG.
FIG. 12 is an exploded perspective view of the piezoelectric vibrator 1 shown in FIG.
In FIG. 12, the excitation electrodes 13 and 14, the extraction electrodes 19 and 20, the mount electrodes 16 and 17, and the weight metal film 21 which will be described later are omitted for easy understanding of the drawing.

  As shown in FIG. 9, the piezoelectric vibrator 1 according to this embodiment includes a package 9 in which a base substrate 2 and a lid substrate 3 are anodically bonded via a bonding film 35, and a piezoelectric vibration housed in a cavity 3 a of the package 9. A surface mount type provided with the piece 4.

  As shown in FIG. 11, the base substrate 2 and the lid substrate 3 are anodic bondable substrates made of a glass material, for example, soda-lime glass, and are formed in a substantially plate shape. A cavity 3 a for accommodating the piezoelectric vibrating reed 4 is formed on the side of the lid substrate 3 that is bonded to the base substrate 2.

  A bonding film 35 (bonding material) for anodic bonding is formed on the entire bonding surface side of the lid substrate 3 with the base substrate 2. The bonding film 35 is formed in the frame area around the cavity 3a in addition to the entire inner surface of the cavity 3a. Although the bonding film 35 of this embodiment is formed of silicon, the bonding film 35 can be formed of chromium, aluminum, or the like. The bonding film 35 and the base substrate 2 are anodically bonded, and the cavity 3a is vacuum-sealed.

  The piezoelectric vibrator 1 includes through electrodes 32 and 33 that penetrate the base substrate 2 in the thickness direction and conduct the inside of the cavity 3 a and the outside of the piezoelectric vibrator 1. The through electrodes 32 and 33 are disposed in the through holes 30 and 31 that penetrate the base substrate 2, and the metal pins 7 that electrically connect the piezoelectric vibrating reed 4 and the outside, the through holes 30 and 31, and the metal And a cylindrical body 6 filled between the pins 7.

The through hole 30 is formed so that the inner diameter gradually increases from the upper surface U side to the lower surface L side of the base substrate 2, and the cross-sectional shape including the central axis P of the through hole 30 is formed in a tapered shape. ing.
The metal pin 7 is a conductive rod-shaped member formed of a metal material such as silver, nickel alloy, or aluminum, and is molded by forging or pressing. The metal pin 7 is preferably formed of a metal having a linear expansion coefficient close to that of the glass material of the base substrate 2, for example, an alloy (42 alloy) containing 58 weight percent iron and 42 weight percent nickel.
The cylinder 6 is obtained by baking paste-like glass frit. At the center of the cylinder 6, a metal pin 7 is arranged so as to penetrate the cylinder 6, and the cylinder 6 is firmly fixed to the metal pin 7 and the through hole 30.

  As shown in FIG. 12, a pair of lead-out electrodes 36 and 37 are patterned on the upper surface U side of the base substrate 2. Further, bumps B made of gold or the like are formed on the pair of lead-out electrodes 36 and 37, respectively, and a pair of mount electrodes of the piezoelectric vibrating reed 4 are mounted using the bumps B. As a result, one mount electrode 17 of the piezoelectric vibrating reed 4 is electrically connected to one through electrode 32 via one routing electrode 36, and the other mount electrode 16 is connected to the other through the other routing electrode 37. The electrode 33 is electrically connected.

  A pair of external electrodes 38 and 39 are formed on the lower surface L of the base substrate 2. The pair of external electrodes 38 and 39 are formed at both ends in the longitudinal direction of the base substrate 2, and are electrically connected to the pair of through electrodes 32 and 33, respectively.

  When the piezoelectric vibrator 1 configured in this way is operated, a predetermined drive voltage is applied to the external electrodes 38 and 39 formed on the base substrate 2. As a result, a voltage can be applied to the first excitation electrode 13 and the second excitation electrode 14 of the piezoelectric vibrating reed 4, so that a predetermined frequency is applied in the X direction so that the pair of vibrating arm portions 10 and 11 approach and separate from each other. It can be vibrated with. The vibration of the pair of vibrating arm portions 10 and 11 can be used as a time source, a timing source for control signals, a reference signal source, and the like.

  According to this embodiment, since the piezoelectric vibrating reed 4 that can suppress an increase in CI value and vibration leakage is provided, a high-performance piezoelectric vibrator 1 can be provided.

In the present embodiment, the configuration using the surface mount type glass package in which the base substrate 2 and the lid substrate 3 are made of a glass material is exemplified. However, the base substrate 2 is made of ceramic and the lid substrate 3 is made of metal or glass. A ceramic package made of a material or the like is also possible.
Further, in the present embodiment, the bump B made of Au or the like is formed on the lead-out electrodes 36 and 37, and the piezoelectric vibration piece 4 is mounted using the bump B. However, the bump B made of Au or the like is exemplified. Instead of this, the piezoelectric vibrating reed 4 may be mounted on the lead-out electrodes 36 and 37 with a conductive adhesive.
In the present embodiment, the piezoelectric vibrating reed 4 of the present invention is adopted for the surface-mount type piezoelectric vibrator 1. However, the present invention is not limited thereto, and for example, the piezoelectric vibrating reed 4 of the present invention is applied to a cylinder package type piezoelectric vibrator. May be adopted.

(Oscillator)
Next, an embodiment of an oscillator according to the present invention will be described with reference to FIG.
As shown in FIG. 13, the oscillator 110 according to the present embodiment is configured by configuring the piezoelectric vibrator 1 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 the piezoelectric vibrator 1 is mounted in the vicinity of the integrated circuit 111. The electronic element component 112, the integrated circuit 111, and the piezoelectric vibrator 1 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 1, the piezoelectric vibrating piece in the piezoelectric vibrator 1 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 1 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. Functions such as controlling time and providing time and calendar can be added.

  According to this embodiment, a high-performance oscillator 110 can be provided.

(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 1 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. 14, the portable information device 120 includes the piezoelectric vibrator 1 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 including an oscillation circuit, a register circuit, a counter circuit, an interface circuit, and the like, and the piezoelectric vibrator 1. When a voltage is applied to the piezoelectric vibrator 1, the piezoelectric vibrating piece vibrates, and the vibration is converted into an electric signal by the piezoelectric characteristics of the crystal, and is 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 cutoff part 136 that can selectively cut off the power supply of the part related to the function of the communication part 124.

  According to the present embodiment, a high-performance portable information device 120 can be provided.

(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. 15, the radio-controlled timepiece 140 of the present embodiment includes the piezoelectric vibrator 1 that is electrically connected to the 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 the property of propagating the surface of the earth and the property of propagating while reflecting the ionosphere and the surface of the earth. 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 1.
The piezoelectric vibrator 1 according to this embodiment includes crystal vibrator portions 148 and 149 having resonance frequencies of 40 kHz and 60 kHz that 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 147, 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 1 having a frequency different from that in Japan is required.

  According to this embodiment, a high-performance radio timepiece 140 can be provided.

  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.

16 to 18 are cross-sectional views showing modifications of the piezoelectric vibrating reeds 41, 42, and 43.
For example, the shape of the groove 5 is not limited to that shown in the above embodiment, and at least a part of the groove 5 located on the bottom wall 5a side of the opening 5c is wider in the Y direction than the opening 5c. 16 and FIG. 17 may be used.
In the piezoelectric vibrating piece 41 shown in FIG. 16, the groove portion 5 is gradually reduced in the X direction and then widened from the opening 5c side toward the bottom wall surface 5a side. Of the groove 5, the end on the bottom wall surface 5 a side along the Z direction is wider in the X direction than the opening 5 c of the groove 5.
In the piezoelectric vibrating piece 42 shown in FIG. 17, the groove 5 has the same width in the X direction on the opening 5 c side from the center in the Z direction. The groove portion 5 gradually widens in the X direction from the center toward the bottom wall surface 5a side. A portion of the groove portion 5 that is located closer to the bottom wall surface 5 a than the center is wider in the X direction than the opening 5 c of the groove portion 5.
Further, as in the piezoelectric vibrating piece 43 shown in FIG. 18, the groove portion 5 may be formed only on the main surface 4 a on one side of the vibrating arm portions 10 and 11.

Further, the groove forming step may include a wet etching step of etching the wafer by wet etching before the dry etching step. The wet etching step can be performed, for example, by immersing the wafer in an etching solution.
In this case, since the groove forming step includes the wet etching step, the time required for etching can be shortened, and productivity can be improved.
Moreover, since the wet etching process is performed before the dry etching process, the groove can be reliably formed with high accuracy. That is, when the wet etching process is performed after the dry etching process, the portion of the groove formed by the dry etching process is also etched by the wet etching process, making it difficult to form the groove with high accuracy. There is a risk.

  In addition, it is possible to appropriately replace the constituent elements in the embodiment with known constituent elements without departing from the spirit of the present invention, and the above-described modified examples may be appropriately combined.

DESCRIPTION OF SYMBOLS 1 Piezoelectric vibrator 4,41,42,43 Piezoelectric vibration piece 4a Main surface 4b Side surface 5 Groove part 5a Bottom wall surface 5b Side wall surface 5c Opening part 10,11 Vibration arm part 12 Base part 13,14 Excitation electrode 40 Wafer 110 Oscillator 120 Portable information Equipment (electronic equipment)
140 radio clock M protective film

Claims (8)

A pair of vibrating arms arranged side by side;
A base to which the pair of vibrating arms are connected;
A pair of excitation electrodes formed on the vibrating arm portion electrically independent from each other and vibrating the vibrating arm portion,
Of the pair of excitation electrodes, one excitation electrode is formed on a side wall surface of a groove portion provided on a main surface of the vibrating arm portion, and the other excitation electrode is formed on a side surface of the vibrating arm portion. In the piezoelectric vibrating piece formed so as to sandwich the vibrating arm portion between the excitation electrode,
A piezoelectric vibrating piece, wherein at least a part of a portion of the groove located on the bottom wall surface side with respect to the opening is wider than the opening in the width direction of the vibrating arm. The piezoelectric vibrating piece according to claim 1,
The piezoelectric vibrating piece according to claim 1, wherein the groove portion is gradually widened in the lateral width direction from the opening side toward the bottom wall surface side. A method of manufacturing a piezoelectric vibrating piece, wherein the piezoelectric vibrating piece according to claim 1 is formed from a wafer,
A groove forming step of forming the groove on the wafer;
The groove part forming step includes a dry etching step of etching the wafer by dry etching after forming a protective film on the wafer,
The method of manufacturing a piezoelectric vibrating piece, wherein the dry etching step is performed a plurality of times with different supply amounts of an etching gas for etching the wafer. A method of manufacturing a piezoelectric vibrating piece according to claim 3,
The groove forming step includes a wet etching step of etching the wafer by wet etching before the dry etching step.   A piezoelectric vibrator comprising the piezoelectric vibrating piece according to claim 1.   An oscillator, wherein the piezoelectric vibrator according to claim 5 is electrically connected to an integrated circuit as an oscillator.   6. An electronic apparatus, wherein the piezoelectric vibrator according to claim 5 is electrically connected to a timer unit.   6. A radio timepiece wherein the piezoelectric vibrator according to claim 5 is electrically connected to a filter portion.

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