JP2004254238A - Piezoelectric device, its manufacturing method, mobile telephone utilizing piezoelectric device and electronic equipment utilizing piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric device of a structure that can be sealed by anode-joining in a short time with good quality, its manufacturing method, a mobile phone and electronic equipment utilizing such a piezoelectric device. <P>SOLUTION: In the piezoelectric device provided with a vibrator substrate 36 formed with a piezoelectric vibrator, a glass-made base substrate 38 and a lid substrate 37 respectively fixed on the vibrator substrate so as to sandwich the vibrator substrate, anode-bonding is applied to the vibrator substrate, the base substrate and the lid substrate respectively to house the piezoelectric vibrator 32 in an internal space S2 inside the base substrate and the lid substrate, at least one of the base substrate and the lid substrate is formed with a through-hole 60 communicating the internal space and the outside, and the through-hole is filled with a sealant to air-tightly seal the internal space. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a piezoelectric device in which a piezoelectric vibrating piece is hermetically housed, a method for manufacturing the same, and a mobile phone device and an electronic apparatus using the piezoelectric device.
[0002]
[Prior art]
In a small information device such as an HDD (hard disk drive), a mobile computer, or an IC card, or a mobile communication device such as a mobile phone, a car phone, or a paging system, a piezoelectric vibrating piece is housed in a package. Piezoelectric devices such as vibrators and piezoelectric oscillators are widely used.
FIG. 12 is an exploded perspective view showing a configuration example of such a piezoelectric device, and FIG. 13 is a schematic sectional view thereof.
In the figure, a piezoelectric device 1 is configured by fixing a vibrating piece substrate 2 having a piezoelectric vibrating piece formed inside a frame portion by sandwiching the same from above and below between a lid substrate 3 and a base substrate 4 (see Patent Document 1). ). Thus, the piezoelectric vibrating reed 2b is accommodated in the internal space S1 formed by the lid substrate 3 and the base substrate 4.
[0003]
As shown in FIG. 13, the resonator element substrate 2 is provided with bonding electrodes 2c and 2d on respective bonding surfaces of the lid substrate 3 and the base substrate 4, and the bonding electrodes 2c and 2d are provided. The resonator element substrate 2 is anodically bonded to the lid substrate 3 and the base substrate 4, respectively.
[0004]
FIG. 14 is a flowchart illustrating a manufacturing process of the piezoelectric device 1.
In the figure, the manufacturing process of the lid substrate 3 and the base substrate 4 is shown from ST1-1 to ST1-3, and the manufacturing process of the piezoelectric vibrating piece 2b is shown from ST2-1 to ST2-4.
Both the lid substrate 3 and the base substrate 4 are formed from a glass substrate. The lid substrate 3 and the base substrate 4 are formed by etching each outer shape from a glass material.
[0005]
Therefore, a corrosion-resistant film corresponding to each outer shape of the lid substrate 3 and the outer shape of the base substrate 4 is formed in advance on a glass material (glass substrate) which is a material suitable for each outer shape (ST1-1). Next, an outer shape is formed by etching (ST1-2), respectively, and the corrosion-resistant film is peeled off (ST1-3) to form a lid substrate 3 and a base substrate 4 having outer shapes as shown in FIG.
For the piezoelectric vibrating reed 2b, for example, a corrosion resistant film corresponding to the outer shape of the vibrating reed substrate 2 is formed in advance using a quartz wafer (ST2-1). Next, the outer shape of the resonator element substrate 2 is formed by etching (ST2-2), and the corrosion-resistant film is removed (ST2-3). Next, an electrode (not shown) required for operation as a piezoelectric vibrating reed is formed (ST2-4).
[0006]
Following the above pre-process, as described with reference to FIG. 13, the resonator element substrate 2 is anodically bonded to the lid substrate 3 and the base substrate 4 (ST5). Next, dicing is performed to the size of each product (ST6), and necessary inspections and the like are performed to complete the piezoelectric device 1 (ST7).
[0007]
[Patent Document 1] JP-A-2000-223996
[0008]
[Problems to be solved by the invention]
However, conventionally, anodic bonding had to be performed in a vacuum atmosphere. That is, the piezoelectric vibrating reed 2b is hermetically sealed so that water vapor and other gases do not remain in the internal space formed by the lid substrate 3 and the base substrate 4. This is because, if water vapor or other gas remains after the sealing, it adheres to the piezoelectric vibrating piece 2b, and the electrode part rusts or a gas component adheres, thereby adversely affecting the vibration performance.
Specifically, conventional anodic bonding has been performed according to a temperature profile as shown in FIG.
That is, as shown in FIG. 15, for example, in a vacuum chamber (not shown), the time from the start to t1 is a temperature rising time required for degassing, and since it is performed in vacuum, heat conduction by air cannot be performed. Requires a long time. Subsequently, the heating is continued from t1 to t2, and the gas components in the internal space S1 are vaporized and driven out into a vacuum. Next, the heating is stopped and the temperature is lowered to a temperature suitable for anodic bonding over a long period of time from t2 to t3, and anodic bonding is performed in a vacuum for a period of time from t3 to t4 (ST5).
[0009]
That is, as shown in FIG. 15, the anodic bonding in a vacuum in the conventional method is performed at a relatively low temperature of about 150 degrees Celsius, so that it takes a long time in a vacuum between t2 and t3. After the temperature of the work is lowered, anodic bonding is performed, and thereafter, the time is about t5, the temperature is cooled to a temperature near normal temperature, and the work is taken out of the vacuum chamber. For this reason, a work time of about 1 hour is required from t3 to t5 in FIG. 15, and a long work time of about 2 hours 30 minutes is required even from the start of FIG. 15 to the end of the anodic bonding from t4. And
Therefore, in the conventional anodic bonding, there is a problem that a long time of about 3 hours is required in all the steps of FIG.
Here, if the anodic bonding in a vacuum is performed at a higher temperature than in the case of FIG. 15, the temperature falling time from t2 to a temperature suitable for anodic bonding corresponding to t3 can be reduced. However, if the anodic bonding is performed at a high temperature, the piezo-electric vibrating piece 2b formed of a piezoelectric material, for example, quartz, and the glass constituting the lid substrate 3 and the base substrate 4 may be bent or bonded due to a difference in thermal expansion coefficient. Another problem is that strain remains behind which can cause breakage.
[0010]
An object of the present invention is to provide a piezoelectric device having a structure that can be sealed by anodic bonding in a short time and with good quality, a method of manufacturing the same, and a mobile phone and an electronic device using such a piezoelectric device.
[0011]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a vibrating reed substrate on which a piezoelectric vibrating reed is formed, and a glass base substrate fixed to the vibrating reed substrate such that the vibrating reed substrate is sandwiched therebetween. A piezoelectric device including a lid substrate, wherein the vibrating piece substrate is anodically bonded to the base substrate and the lid substrate, respectively, so that the piezoelectric vibrating piece is provided in an internal space inside the base substrate and the lid substrate. Is housed, and at least one of the base substrate and the lid substrate has a through-hole formed therein, which communicates the internal space with the outside.By filling the through-hole with a sealing material, This is achieved by a piezoelectric device in which the internal space is sealed in a closed state.
[0012]
According to the configuration of the first invention, either the base substrate or the lid substrate has a through hole. For this reason, after the vibrating reed substrate, the base substrate, and the lid substrate are respectively anodically bonded, the through-holes can be used as holes for removing internal gas. That is, since the anodic bonding can be performed at atmospheric pressure, the time required to raise the temperature to a required temperature can be reduced. Moreover, unlike the conventional case, it is not necessary to reduce the temperature to a temperature suitable for anodic bonding over a long time after degassing in a vacuum, so that the time required for the entire process can be shortened and the manufacturing cost can be reduced. After the joining, the gas inside of the through-hole is exhausted to remove the gas that adversely affects the vibration characteristics of the piezoelectric vibrating reed, so that the vibration performance is not deteriorated, and the through-hole is sealed. Since the piezoelectric vibrating reed is closed by the material, the sealing performance is properly secured.
As described above, according to the present invention, it is possible to provide an effect that a piezoelectric device having a structure that can be sealed by anodic bonding in a short time and with good quality can be provided.
[0013]
According to a second aspect of the present invention, in the configuration of the first aspect, the vibrating reed substrate is provided with a frame having an open upper end and a lower end, and a piezoelectric member provided integrally with the frame inside the frame. And a vibrating reed.
According to the configuration of the second aspect of the invention, the piezoelectric vibrating reed can be bonded to the lid substrate and the base substrate by using the frame, so that the labor for bonding the small piezoelectric vibrating reed inside the package is unnecessary.
[0014]
According to a third aspect of the present invention, in the configuration of the second aspect, the piezoelectric vibrating reed includes a base formed integrally with the inner surface of the frame, and a pair of vibrating arms extending in parallel from the base. A vibrating reed, wherein each of the vibrating arms is formed with a groove extending in a length direction.
According to the configuration of the third invention, the electric field efficiency can be improved by forming the piezoelectric vibrating piece as a tuning fork type vibrating piece and forming a groove extending in the length direction on each of the vibrating arms.
[0015]
In a fourth aspect based on the configuration of the third aspect, the base portion includes a cutout portion between the region formed integrally with the inner surface of the frame and the vibrating arm. I do.
According to the configuration of the fourth aspect of the invention, when the piezoelectric vibrating reed is a tuning fork vibrating reed, the notch is formed in the base, thereby effectively preventing the vibration from the resonating arm from leaking into the base. Can be prevented, and the crystal impedance value can be suppressed.
[0016]
According to a fifth aspect of the present invention, there is provided a vibrating reed substrate on which a piezoelectric vibrating reed is formed, and a glass base fixed to the vibrating reed substrate so as to sandwich the vibrating reed substrate therebetween. A method for manufacturing a piezoelectric device comprising a substrate and a lid substrate, wherein the base substrate and the lid substrate each having a through hole formed in at least one of them are provided, and a driving electrode is provided on the resonator element substrate, and the base substrate And a bonding electrode provided on a bonding surface with the lid substrate, anodically bonding the vibrating piece substrate, the base substrate and the lid substrate in the air, and sealing the through hole in a vacuum. This is achieved by a method for manufacturing a piezoelectric device.
[0017]
According to the configuration of the fifth aspect, when manufacturing the base substrate and the lid substrate made of glass, a through hole is provided in one of them. Then, an electrode for bonding is provided on a bonding surface between the base substrate and the lid substrate, and the vibrating piece substrate is anodically bonded to the base substrate and the lid substrate at atmospheric pressure. That is, since the anodic bonding is performed at atmospheric pressure, the time required to raise the temperature to the temperature required for bonding can be reduced. Moreover, unlike the conventional case, it is not necessary to reduce the temperature to a temperature suitable for anodic bonding over a long time after degassing in a vacuum, so that the time required for the entire process can be reduced. After that, in a vacuum, the gas inside is discharged from the through-hole, and after this through-hole is closed with a sealing material, gas is generated inside and adheres to the piezoelectric vibrating reed to improve the vibration performance. An adverse effect can be effectively prevented.
[0018]
A sixth invention is characterized in that, in the configuration of the fifth invention, after the anodic bonding, before the hole sealing, the piezoelectric vibrating reed is subjected to a heat treatment at a temperature higher than a reflow temperature for mounting in a vacuum. I do.
According to the configuration of the sixth aspect, after the anodic bonding, the piezoelectric vibrating piece is moved to a vacuum atmosphere and heated at a temperature higher than the reflow temperature at the time of mounting the piezoelectric device. A gas such as water vapor is generated. If this gas component is exhausted into a vacuum and the through-hole is sealed, even if it is heated in a reflow furnace when the piezoelectric device is mounted, gas is generated inside the mounting process and the piezoelectric vibrating piece To prevent the vibration performance from being adversely affected.
[0019]
According to a seventh aspect of the present invention, there is provided a vibrating piece substrate having a piezoelectric vibrating piece formed thereon, and a glass base fixed to the vibrating piece substrate so as to sandwich the vibrating piece substrate therebetween. An electronic device using a piezoelectric device including a substrate and a lid substrate, wherein the vibrating piece substrate and the base substrate and the lid substrate are respectively anodically bonded, thereby forming an inner portion of the base substrate and the lid substrate. The piezoelectric vibrating reed is housed in the internal space, and at least one of the base substrate and the lid substrate is formed with a through-hole communicating the internal space and the outside, and the through-hole is sealed. This is achieved by an electronic device in which a clock signal for control is obtained by a piezoelectric device in which the internal space is hermetically sealed by filling a material. It is.
[0020]
Further, according to the eighth aspect of the present invention, there is provided a vibrating piece substrate on which a piezoelectric vibrating piece is formed, and a glass base fixed to the vibrating piece substrate so as to sandwich the vibrating piece substrate therebetween. A mobile phone device using a piezoelectric device including a substrate and a lid substrate, wherein the vibrating piece substrate, the base substrate, and the lid substrate are respectively anodically bonded, so that the inside of the base substrate and the lid substrate is The piezoelectric vibrating reed is accommodated in the internal space of the base plate, and at least one of the base substrate and the lid substrate is formed with a through-hole for communicating the internal space with the outside. A portable telephone device in which a control clock signal is obtained by a piezoelectric device in which the internal space is hermetically sealed by filling a stopper material. , It is achieved.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
1 to 7 show an embodiment of the piezoelectric device of the present invention. FIG. 1 is a schematic exploded perspective view, FIG. 2 is a schematic plan view of a resonator element substrate of the piezoelectric device in FIG. 1, and FIG. 2 is a schematic cross-sectional view taken along the line AA of FIG. 2, FIG. 4 is a schematic bottom view of the resonator element substrate of the piezoelectric device of FIG. 1, FIG. 5 is a cross-sectional end view taken along the line BB of FIG. 6 is a schematic sectional view showing a state of anodic bonding, and FIG. 7 is a sectional view taken along the line CC of FIG.
[0022]
FIG. 1 shows an example in which a piezoelectric device 30 is configured as a piezoelectric vibrator. The piezoelectric device 30 is formed by fixing upper and lower openings (described later) of the resonator element substrate 36 with a lid substrate 37 and a base substrate 38, respectively.
The lid substrate 37 and the base substrate 38 are each formed of the same glass material.
The lid substrate 37 has a size that closes at least the upper opening 36a of the resonator element substrate 36 shown in FIG. 1, and in this embodiment, since the external shape of the resonator element substrate 36 is rectangular, the lid substrate 37 also has a rectangular shape. It has been. The base substrate 38 has a size to close at least the lower opening 36b of the resonator element substrate 36 shown in FIG. 1, and in this embodiment, since the external shape of the resonator element substrate 36 is rectangular, the base substrate 38 is also rectangular. It is shaped.
[0023]
The lid substrate 37 and the base substrate 38 have the same outer shape, and have the same outer shape as the outer shape of the resonator element substrate 36. As shown in FIG. 1, the lid substrate 37 has a concave portion 37a, and the base substrate 38 has a concave portion 38a.
The lid substrate 37 and the base substrate 38 are fixed so that the respective concave portions 37a and 38a face each other and the vibrating piece substrate 36 is interposed therebetween, whereby the respective concave portions 37a and 38a will be described later. The internal space S2 for accommodating the piezoelectric vibrating reed 32 is formed integrally with the space inside the vibrating reed substrate 36.
[0024]
As shown in FIG. 1, the resonator element substrate 36 is a rectangular frame having an open upper end and a lower end and having a gap or space inside. As shown in FIG. 1, a lid substrate 37 and a base substrate 38 are fixed to the open upper end and the lower end of the resonator element substrate 36, thereby sealing the internal space S2. I have.
The resonator element substrate 36 does not necessarily have to be a quadrangle as shown in FIG. 1, but may be an ellipse with a rounded corner, an oval, or the like. In the case of the present embodiment, as shown in FIG. 1, the resonator element substrate 36 is formed as a rectangular frame that is long in one direction and has a small thickness.
[0025]
In particular, a piezoelectric material is used for the vibrating piece substrate 36 to form the piezoelectric vibrating piece 32 inside. As the piezoelectric material to be used, quartz is suitable as in this embodiment, and other than quartz, for example, a piezoelectric material such as lithium tantalate or lithium niobate can be used. In the case of the present embodiment, the resonator element substrate 36 forms the inner space and the outer shape of the piezoelectric resonator element 32 by etching a thin quartz plate.
[0026]
The piezoelectric vibrating reed 32 is integrally formed of the same material as the vibrating reed substrate 36. In the case of the present embodiment, the piezoelectric vibrating reed 32 is formed in a small size and is particularly illustrated in order to obtain necessary performance. It is shaped.
That is, in FIG. 2, the piezoelectric vibrating reed 32 is divided into a base 51 integrated with the inside of one end of the vibrating reed substrate 36 and a bifurcated rightward in FIG. And a pair of vibrating arms 34 and 35 extending in parallel to each other, and is a so-called tuning fork type piezoelectric vibrating reed having a whole shape like a tuning fork.
Preferably, the pair of vibrating arms 34, 35 of the piezoelectric vibrating reed 32 have long grooves 34a, 35a extending in the longitudinal direction, respectively, as shown in FIG. In this case, as shown in FIG. 5, the long grooves 34a and 35a are respectively formed on the upper and lower surfaces of the vibrating arms 34 and 35 in a similar manner.
[0027]
As described above, the pair of vibrating arms 34 and 35 are formed with the long grooves 34a and 35a extending in the longitudinal direction, respectively, and the first and second excitation electrodes 41b and 42b are formed in the long grooves 34a and 35a, respectively. Thereby, there is an advantage that the electric field efficiency in the vibrating arms 34 and 35 is improved. In FIG. 1, illustration of electrodes such as the excitation electrodes 41b and 42b is omitted in order to avoid complexity of illustration.
A notch provided between the base 51 and the pair of vibrating arms 34 and 35, which is a region integrally fixed to the inner surface of the vibrating reed substrate 36 of the piezoelectric vibrating reed 32, having a reduced width in the width direction of the base 51. Or constricted portions 52, 52 are provided.
Thereby, the leakage of the vibration of the piezoelectric vibrating reed 32 to the base 51 side can be prevented, and the CI (crystal impedance) value can be reduced.
[0028]
As shown in FIG. 2, a first electrode 41 is formed on the upper end surface 36c of the resonator element substrate 36. As shown by reference numeral 41a in FIG. 2, the first electrode 41 is connected to the first bonding electrode 41a routed to the upper end surface 36c of the resonator element substrate 36, and is connected to the first bonding electrode 41a. Then, the first excitation electrode 41b is routed through the surface of the base 51 of the piezoelectric vibrating reed 32 and on both sides of the vibrating arm 34 and the upper and lower surfaces of the vibrating arm 35.
Further, as shown in FIG. 4, a second electrode 42 is formed on the lower end surface 36d of the resonator element substrate 36. As shown by reference numeral 42a in FIG. 4, the second electrode 42 extends from the second bonding electrode 42a extended around the lower end surface 36d of the resonator element substrate 36, and extends from the second bonding electrode 42a. Then, the second excitation electrode 42b is routed through the back surface of the base 51 of the piezoelectric vibrating reed 32, on both sides of the vibrating arm 35, and on the upper and lower surfaces of the vibrating arm 34.
[0029]
These electrodes have the following structural features.
The first bonding electrode 41a and the second bonding electrode 42a are used for anodic bonding to the resonator element substrate 36, the lid substrate 37, and the base substrate 38, respectively. The first excitation electrode 41b and the second excitation electrode 42b are used to drive the piezoelectric vibrating reed 32.
The first bonding electrode 41a and the second bonding electrode 42a, and the first excitation electrode 41b and the second excitation electrode 42b are formed, for example, on the surface of the vibrating piece substrate 36 formed of quartz, for example. A common structure is provided in which a (Cr) layer is formed and a gold (Au) layer is provided thereon.
[0030]
Further, the first bonding electrode 41a and the second bonding electrode 42a are provided on the gold layer as a metal coating layer for anodic bonding, for example, an aluminum (Al) layer or, instead of this, It is formed by covering with tungsten, silicon, nickel, titanium and the like.
Also, as shown in FIG. 6, the first bonding electrode 41a is routed to the bottom surface of the base substrate 38 as a side electrode 45a on the left side surface in FIG. It is connected to the mounting electrode 45 provided at the end. Similarly, the second bonding electrode 42a is routed to the bottom surface of the base substrate 38 as a side electrode 46a on the right side surface in FIG. Is connected to
[0031]
As a particularly important configuration, as shown in FIG. 6, in the present embodiment, a through hole 60 that connects the internal space S2 to the outside is provided near the center of the lid substrate 37. The through-hole 60 has a form in which the two through-holes 61 and the through-hole 62 communicate with each other. The outer first hole 62 is formed to have a larger inner diameter than the second hole 61 that opens to the internal space S2 side. An outward step 63 is formed between the first hole 62 and the second hole 61. The through hole 60 is sealed with a sealing material as described later.
[0032]
As shown in FIG. 1, the flat portion 37c of the lid substrate 37 described with reference to FIGS. 1 and 2 is fixed to the upper end surface 36c of the resonator element substrate 36, and the lower end surface 36d of the resonator element substrate 36 Is fixed to the flat portion 38c of the base substrate 38 described with reference to FIGS.
Specifically, as shown in FIG. 6, a lid substrate 37 and a base substrate 38 made of glass are applied to a lid substrate 37 and a base substrate 38 at a temperature lower than their softening points. And the bonding electrodes 41a and 42a, which are bonding films for bonding them to the resonator element substrate 36, such that the bonding electrodes 41a and 42a serve as anodes. Apply voltage.
That is, anodic bonding is a method in which surfaces are brought into close contact with each other and bonded in a solid phase, and a method is used in which surfaces having a smooth surface are bonded by generating surface atoms. Therefore, ions move to the lid substrate 37 and the base substrate 38 made of glass by the action of the applied DC voltage, and the space charge formed in the gap between these and the bonding electrodes 41a and 42a and in the vicinity thereof. The layer is subjected to a continuously applied voltage. Then, an electrostatic attraction is generated between the lid substrate 37 and the base substrate 38 and each of the bonding electrodes 41a and 42a, and the electrodes come into close contact with each other. It is considered that a covalent bond is formed with an atom on the electrode side at the step S1 to form the bond. This process can also be reversibly advanced using a reverse voltage.
Thus, the internal space S2 is hermetically sealed by the lid substrate 37 and the base substrate 38 so as to sandwich the resonator element substrate 36 between the lid substrate 37 and the base substrate 38.
[0033]
The piezoelectric device 30 of the present embodiment is configured as described above. Next, a method for manufacturing the piezoelectric device 30 will be described.
FIG. 8 is a flowchart illustrating an embodiment of a method for manufacturing a piezoelectric device.
In the figure, the manufacturing process of the lid substrate 37 and the base substrate 38 is shown from ST11 to ST13, and the manufacturing process of the piezoelectric vibrating reed 32 is shown from ST21 to ST24 (previous process).
First, the preceding process will be described.
The lid substrate 37 and the base substrate 38 are both formed of the same glass material. That is, in order to enable anodic bonding or to facilitate anodic bonding, a glass material in which ions are easily diffused is selected, and a material containing an alkali metal and suitable for etching is selected. Under these conditions, for example, soda glass is suitable.
[0034]
The lid substrate 37 and the base substrate 38 are formed by etching the respective outer shapes using a glass substrate of a predetermined size made of the above-described material.
Therefore, a corrosion-resistant film corresponding to each outer shape of the lid substrate 37 and the base substrate 38 is formed in advance on a glass substrate (not shown) so as to conform to each outer shape (ST11). Next, the outer shapes of the lid substrate 37 and the base substrate 38 are formed by etching, respectively (ST12).
[0035]
What is important here is that the through hole 60 shown in FIGS. 6 and 7 is formed in either the lid substrate 37 or the base substrate 38. In the present embodiment, the through hole 60 is formed substantially near the center of the lid substrate 37. The through hole 60 can be formed at the same time as the outer shape etching of the lid substrate 37 by removing a corresponding portion of the corrosion resistant film in advance. That is, in this step, a hole having an inner diameter corresponding to the second hole 61 of the through hole 60 is formed.
Next, the outer shapes of the lid substrate 37 and the base substrate 38 described with reference to FIG. 1 and the like are formed by removing the corrosion-resistant film (ST13).
Subsequently, a necessary corrosion-resistant film is formed on the lid substrate 37 and the base substrate 38, and half-etching is performed to form the concave portions 37a and 38a described in FIG. 1 (ST14).
Finally, with respect to the substrate provided with the through-hole 60, the periphery of the hole formed in ST13 is exposed, a corrosion-resistant film is formed in other portions, and half-etching is performed, so that the first hole 62 of the through-hole 60 is formed. Is formed (ST15).
Thus, the lid substrate 37 and the base substrate 38 are completed.
[0036]
For the piezoelectric vibrating reed 32, a corrosion-resistant film corresponding to the outer shape of the vibrating reed substrate 36 is formed in advance on a substrate (not shown) using a substrate such as a quartz wafer (ST21). Next, the outer shape of the resonator element substrate 36 is formed by etching using an etching solution such as hydrofluoric acid (ST22), and the corrosion-resistant film is removed (ST23). Next, an electrode required for operation as the piezoelectric vibrating reed 32 and an electrode used as a bonding film for anodic bonding are formed. Such an electrode has, for example, the configuration described in FIG. 2 to FIG. 4, and forms the first electrode 41 and the second electrode 42 described based on these drawings (ST24). ).
[0037]
That is, the first electrode 41 and the second electrode 42 have a common configuration in which, for example, a chromium (Cr) layer is formed in a corresponding portion of the resonator element substrate 36 and a gold (Au) layer is provided thereon. The first bonding electrode 41a and the second bonding electrode 42a are formed on the gold layer as a metal coating layer for anodic bonding, for example, an aluminum (Al) layer, Instead, tungsten, silicon, nickel, titanium, or the like is provided by a method such as sputtering or vapor deposition.
[0038]
Next, a post process will be described.
As described with reference to FIG. 6, the resonator element substrate 36 is anodically bonded to the lid substrate 37 and the base substrate 38 (ST35).
This anodic bonding step can be performed at atmospheric pressure without the need to discharge gas from the internal space S2 as in the related art. Therefore, for example, it can be executed according to a temperature profile as shown in FIG.
As shown in FIG. 6, between the lid substrate 37 and the base substrate 38 and the bonding electrodes 41a and 42a which are bonding films for bonding them to the resonator element substrate 36, these bonding electrodes 41a and 42a are formed. A DC voltage is applied from the DC power supply 39 so that the side becomes the anode.
[0039]
At this time, as shown in FIG. 9, the time Ht1 for heating from the start to the temperature L1 required for anodic bonding does not need to be degassed in a vacuum atmosphere as in the prior art. Heating can be performed in a very short time because it is heating and does not require a high temperature required for degassing. That is, the temperature L1 is about 150 degrees Celsius (hereinafter, all the temperature indications are "Celsius"). Therefore, the temperature is raised to the temperature L1 (Ht1), and it takes about 3 minutes until the anodic bonding is completed after the temperature rise. Therefore, the time from the start until the anodic bonding is completed is about 8 minutes.
[0040]
Next, the workpiece is moved to a vacuum chamber (not shown) to lower the temperature to L2, and from time Ht3 to time Ht4, is heated again to temperature L3 to perform an annealing process (ST36). The temperature L3 is preferably higher than the reflow temperature performed when the piezoelectric device 30 is mounted. For this reason, heating is performed to a temperature appropriately selected, for example, from 260 ° C. to about 300 ° C. This is because this annealing treatment is to prevent degassing during reflow. Therefore, the temperature is raised to, for example, about 300 degrees as the temperature L3, and the gas that flows out of the inside of the piezoelectric vibrating reed 32, the lid substrate 37, and the base substrate 38 is exhausted from the through hole 60 for about 30 minutes in the internal space S2.
[0041]
In FIG. 9, at time Ht5 which is the last time of temperature L3, hole sealing is performed (ST37). This hole sealing is performed in a vacuum chamber as follows.
As shown in FIG. 10, a sealing material 70 is arranged in the through hole 60 of the lid substrate 37. The sealing material 70 is at least partially received in the first hole 62 of the through hole 60 and has an outer shape larger than the inner diameter of the second hole 61, so that the sealing material 70 falls or completely enters the inside of the lid substrate 37. It is preferable that the size does not enter. For this reason, in the present embodiment, for example, a spherical sealing material 70 is used.
[0042]
The sealing material 70 is melted and filled in the first hole 62 and / or the second hole 61 of the through hole 60, and is preferably made of a material that can be easily bonded to the lid substrate 37. Further, it is preferable that the piezoelectric device 30 does not easily melt due to the heating temperature in the reflow step. Under such conditions, an Au-Sn alloy or an Au-Ge alloy can be used. In addition, as the sealing material 70, low melting point glass or the like can be used in consideration of ease of joining with the lid substrate 37.
Then, as shown in FIG. 10, such a sealing material 70 is positioned in the first hole 62 of the through hole 60, and is irradiated with a laser beam LB or the like from the outside and melted. Thereby, the hole sealing is completed by filling the molten sealing material 70 so as to close the through hole 60. After that, the temperature is lowered in the vacuum chamber for a time period up to Ht6 in FIG. 9 and is taken out of the vacuum chamber. In addition, it is also possible to take out to the air immediately after sealing the holes and further reduce the cooling time. On the other hand, in consideration of protection of the package from thermal stress, it is more preferable to lower the temperature in the vacuum chamber as shown in FIG.
Next, the product is diced to the size of each product (ST38), and necessary inspections and the like are performed to complete the piezoelectric device 30 (ST39).
[0043]
As described above, according to the present embodiment, the through holes 60 are provided in the lid substrate 37. That is, the through-hole 60 is used as a hole for removing gas from the internal space S2 after the resonator element substrate 36 is anodically bonded to the base substrate 38 and the lid substrate 37, respectively. As a result, the anodic bonding can be performed at the atmospheric pressure, and the time required to raise the temperature to the required temperature L1 can be reduced, so that the manufacturing cost can be reduced. After the joining, the gas inside the through-hole 60 is exhausted to remove the gas that adversely affects the vibration characteristics of the piezoelectric vibrating piece 32, so that the vibration performance is not deteriorated. Since the stopper 70 is closed, the piezoelectric vibrating reed 32 is properly sealed, and the sealing performance is ensured.
Therefore, it is possible to provide the piezoelectric device 30 having a structure that can be sealed by anodic bonding with high quality in a short time.
[0044]
FIG. 11 is a diagram illustrating a schematic configuration of a digital mobile phone device as an example of an electronic apparatus using the piezoelectric device according to the embodiment of the present invention.
In the figure, a microphone 308 for receiving the voice of the sender and a speaker 309 for outputting the received content as a voice output are provided, and further, an integrated circuit or the like as a control unit connected to the modulation and demodulation unit of the transmission / reception signal is provided. CPU (Central Processing Unit) 301.
The CPU 301 controls the input / output unit 302 including an LCD as an image display unit and operation keys for inputting information, and the memory 303 including a RAM and a ROM, in addition to the modulation and demodulation of transmission / reception signals. It has become. For this reason, the piezoelectric device 30 is attached to the CPU 301, and its output frequency is used as a clock signal suitable for the control content by a predetermined frequency dividing circuit (not shown) or the like built in the CPU 301. ing. The piezoelectric device 30 attached to the CPU 301 is not limited to the piezoelectric device 30 alone, but may be an oscillator combining the piezoelectric device 30 or the like with a predetermined frequency dividing circuit or the like.
[0045]
The CPU 301 is further connected to a temperature-compensated crystal oscillator (TCXO) 305, and the temperature-compensated crystal oscillator 305 is connected to a transmitting unit 307 and a receiving unit 306. Thus, even if the frequency of the basic clock from the CPU 301 fluctuates due to a change in the environmental temperature, the frequency is corrected by the temperature-compensated crystal oscillator 305 and provided to the transmission unit 307 and the reception unit 306.
[0046]
As described above, by using the piezoelectric device 30 according to the above-described embodiment in an electronic device such as the digital mobile phone device 300 including the control unit, even if the electronic device is efficiently manufactured in a short time at a low cost, An accurate clock signal can be generated without adversely affecting the vibration performance of the piezoelectric vibrating reed 32 due to the adhesion of the gas.
[0047]
The invention is not limited to the embodiments described above. Each configuration of each embodiment can be appropriately combined or omitted, and can be combined with another configuration not shown.
In particular, the structure for arranging the electrodes of the piezoelectric vibrating reed is not limited to the example described in the above embodiment, and various structures can be adopted.
In addition, the present invention can be applied to all piezoelectric devices regardless of the names of the piezoelectric vibrator, the piezoelectric oscillator, and the like as long as the piezoelectric vibrating reed is housed in the package.
[Brief description of the drawings]
FIG. 1 is a schematic exploded perspective view showing an embodiment of a piezoelectric device of the present invention.
FIG. 2 is a schematic plan view of a resonator element substrate of the piezoelectric device of FIG.
FIG. 3 is a schematic sectional view taken along line AA of FIG. 2;
FIG. 4 is a schematic bottom view of a resonator element substrate of the piezoelectric device of FIG. 1;
FIG. 5 is a sectional view taken along the line BB of FIG. 1;
FIG. 6 is a schematic sectional view showing a state of anodic bonding of the piezoelectric device of FIG. 1;
FIG. 7 is a sectional end view taken along line CC of FIG. 6;
FIG. 8 is a flowchart illustrating an embodiment of a method for manufacturing a piezoelectric device according to the present invention.
FIG. 9 is a graph showing an example of a temperature profile of anodic bonding and annealing in the manufacturing process of FIG. 8;
FIG. 10 is an explanatory view showing a state of hole sealing in the manufacturing process of FIG. 8;
FIG. 11 is a view showing a schematic configuration of a digital mobile phone device as an example of an electronic apparatus using a piezoelectric device according to an embodiment of the present invention.
FIG. 12 is an exploded perspective view showing an example of a conventional piezoelectric device.
FIG. 13 is a schematic sectional view of the piezoelectric device of FIG.
FIG. 14 is a flowchart showing a method for manufacturing the piezoelectric device of FIG.
FIG. 15 is a graph showing a temperature profile of anodic bonding and annealing in the manufacturing process of FIG. 14;
[Explanation of symbols]
Reference numeral 30 denotes a piezoelectric device, 32 denotes a piezoelectric vibrating reed, 36 denotes a vibrating reed substrate, 37 denotes a lid substrate, 38 denotes a base substrate, 41a and 42a denotes a bonding electrode, 41b... 1st excitation electrode, 42b ... 2nd excitation electrode, 51 ... base.

Claims (8)

A vibrating reed substrate on which a piezoelectric vibrating reed is formed, and a piezoelectric device including a glass base substrate and a lid substrate respectively fixed to the vibrating reed substrate, with the vibrating reed substrate interposed therebetween,
The piezoelectric vibrating reed is accommodated in an internal space inside the base substrate and the lid substrate by the vibrating reed substrate and the base substrate and the lid substrate being respectively anodically bonded,
In addition, at least one of the base substrate and the lid substrate is formed with a through hole that communicates the internal space with the outside. By filling the through hole with a sealing material, the internal space is sealed. A piezoelectric device characterized by being sealed in a piezoelectric device. 2. The vibrating piece substrate according to claim 1, further comprising: a frame having an open upper end and a lower end; and a piezoelectric vibrating piece integrally provided inside the frame with respect to the frame. 3. The piezoelectric device as described. The piezoelectric vibrating reed is a tuning fork vibrating reed including a base integrally formed on the inner surface of the frame, and a pair of vibrating arms extending in parallel from the base, and each of the vibrating arms has a length. The piezoelectric device according to claim 2, wherein a groove extending in the direction is formed. 4. The piezoelectric device according to claim 3, wherein the base has a notch between the region formed integrally with the inner surface of the frame and the vibrating arm. 5. A method of manufacturing a piezoelectric device including a vibrating reed substrate on which a piezoelectric vibrating reed is formed, and a glass base substrate and a lid substrate respectively fixed to the vibrating reed substrate, with the vibrating reed substrate interposed therebetween,
Prepare the base substrate and the lid substrate having a through hole formed in at least one of them,
A driving electrode on the resonator element substrate, and a bonding electrode provided on a bonding surface between the base substrate and the lid substrate,
The vibrating piece substrate, the base substrate and the lid substrate are anodically bonded in the air,
Further, a method of manufacturing a piezoelectric device, comprising sealing the through-hole in a vacuum. The method for manufacturing a piezoelectric device according to claim 5, wherein after the anodic bonding and before the hole sealing, the piezoelectric vibrating reed is subjected to a heat treatment in a vacuum at a temperature higher than a reflow temperature for mounting. An electronic device using a piezoelectric device including a vibrating reed substrate on which a piezoelectric vibrating reed is formed, and a glass base substrate and a lid substrate fixed to the vibrating reed substrate with the vibrating reed substrate interposed therebetween. hand,
The piezoelectric vibrating reed is accommodated in an internal space inside the base substrate and the lid substrate by the vibrating reed substrate and the base substrate and the lid substrate being respectively anodically bonded,
In addition, at least one of the base substrate and the lid substrate is formed with a through hole that communicates the internal space with the outside. By filling the through hole with a sealing material, the internal space is sealed. An electronic device characterized in that a control clock signal is obtained by a piezoelectric device sealed in the electronic device. A mobile phone device using a piezoelectric device including a vibrating reed substrate on which a piezoelectric vibrating reed is formed, and a glass base substrate and a lid substrate respectively fixed to the vibrating reed substrate so as to sandwich the vibrating reed substrate therebetween. So,
The piezoelectric vibrating reed is accommodated in an internal space inside the base substrate and the lid substrate by the vibrating reed substrate and the base substrate and the lid substrate being respectively anodically bonded,
In addition, at least one of the base substrate and the lid substrate is formed with a through hole that communicates the internal space with the outside. By filling the through hole with a sealing material, the internal space is sealed. A cellular phone device characterized in that a control clock signal is obtained by a piezoelectric device sealed in the mobile phone device.

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