JP3873902B2 - Piezoelectric device, manufacturing method thereof, mobile phone device using the piezoelectric device, and electronic equipment using the piezoelectric device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric device in which a piezoelectric vibrating piece is housed in an airtight manner, a manufacturing method thereof, and a cellular phone device and an electronic apparatus using the piezoelectric device.
[0002]
[Prior art]
Piezoelectric vibrating piece housed in a package for small information devices such as HDDs (hard disk drives), mobile computers, IC cards, and mobile communication devices such as mobile phones, car phones, and paging systems 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 between a lid substrate 3 and a base substrate 4 from above and below (see Patent Document 1). ). Thereby, the piezoelectric vibrating piece 2 b is accommodated in the internal space S <b> 1 formed by the lid substrate 3 and the base substrate 4.
[0003]
As shown in FIG. 13, the vibrating reed substrate 2 is provided with bonding electrodes 2c and 2d on the bonding surfaces of the lid substrate 3 and the base substrate 4, and the bonding electrodes 2c and 2d. The vibrating reed substrate 2 is anodically bonded to the lid substrate 3 and the base substrate 4 respectively.
[0004]
FIG. 14 is a flowchart showing the 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 of glass substrates. 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 base substrate 4 is formed in advance on a glass material (glass substrate) as a material in conformity with each outer shape (ST1-1). Next, the outer shape is formed by etching (ST1-2), the corrosion-resistant film is peeled off (ST1-3), and the lid substrate 3 and base substrate 4 having the outer shape as shown in FIG. 12 are formed.
For the piezoelectric vibrating piece 2b, for example, a quartz wafer is used to previously form a corrosion-resistant film corresponding to the outer shape of the vibrating piece substrate 2 (ST2-1). Next, the outer shape of the resonator element 2 is formed by etching (ST2-2), and the corrosion-resistant film is peeled off (ST2-3). Next, an electrode (not shown) required for operation as a piezoelectric vibrating piece is formed (ST2-4).
[0006]
Subsequent to the foregoing 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, the product is diced into individual product sizes (ST6), and necessary inspections are performed to complete the piezoelectric device 1 (ST7).
[0007]
[Patent Document 1]
JP 2000-223996
[0008]
[Problems to be solved by the invention]
However, conventionally, anodic bonding has to be performed in a vacuum atmosphere. That is, the piezoelectric vibrating piece 2 b is 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 sealing, it adheres to the piezoelectric vibrating piece 2b, rusts the electrode part, or adheres gas components, thereby adversely affecting the vibration performance.
Specifically, the conventional anodic bonding is 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), from the start to t1 is a temperature rising time necessary for degassing, and since it is performed in a vacuum, heat conduction by air cannot be performed. Requires a long time. Subsequently, 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 time from t2 to t3, and anodic bonding is performed in a vacuum during the 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 a long time is taken in the vacuum between t2 and t3. Then, the temperature of the workpiece is lowered, and then anodic bonding is performed. Thereafter, the time is about t5, and the workpiece is cooled to a temperature close to room temperature and taken out from the vacuum chamber. Therefore, about 1 hour work time is required from t3 to t5 in FIG. 15, and a long time of about 2 hours 30 minutes is required from the start of FIG. 15 to the end of anodic bonding from t4 to t4. It is said.
Therefore, in the conventional anodic bonding, the entire process of FIG. 15 from the start to the removal takes a long time of about 3 hours and there is a problem that the manufacturing efficiency is poor.
Here, if anodic bonding in vacuum is performed at a higher temperature than in the case of FIG. 15, the temperature drop time from t2 to a temperature suitable for anodic bonding corresponding to t3 can be shortened. However, if anodic bonding is performed at a high temperature, the piezoelectric 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 later, causing damage.
[0010]
An object of the present invention is to provide a piezoelectric device having a structure capable of being sealed by anodic bonding with high quality in a short time, a manufacturing method thereof, and a mobile phone and an electronic apparatus using such a piezoelectric device.
[0011]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided a vibrating plate substrate on which a piezoelectric vibrating piece is formed, a glass base substrate fixed to the vibrating plate substrate, with the vibrating plate substrate interposed therebetween, and A piezoelectric device including a lid substrate, wherein the vibration piece substrate, the base substrate, and the lid substrate are anodically bonded to each other, whereby the piezoelectric vibration piece is provided in an internal space inside the base substrate and the lid substrate. And 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, and by filling the through hole with a sealing material, This is achieved by a piezoelectric device in which the internal space is hermetically sealed.
[0012]
According to the configuration of the first invention, the base substrate or the lid substrate is provided with a through hole. For this reason, the through-hole can be used as a hole for venting an internal gas after the vibrating plate substrate, the base substrate, and the lid substrate are each anodically bonded. In other words, since anodic bonding can be performed at atmospheric pressure, the time required for raising the temperature to the required temperature can be reduced. Moreover, unlike the prior art, after degassing in a vacuum, it is not necessary to lower the temperature to a temperature suitable for anodic bonding over a long time, so that the time required for the entire process can be shortened and the manufacturing cost can be reduced. Then, after joining, the internal gas is discharged from the through hole, and the gas that adversely affects the vibration characteristics of the piezoelectric vibrating piece is removed, so that the vibration performance is not deteriorated, and the through hole is sealed. Since it is closed by the material, the piezoelectric vibrating piece is properly sealed, and sealing performance is also ensured.
Thus, according to the present invention, it is possible to provide an effect that it is possible to provide a piezoelectric device having a structure capable of being sealed by anodic bonding with high quality in a short time.
[0013]
According to a second aspect of the present invention, in the configuration of the first aspect, the vibrating reed substrate is a frame having an open upper end and a lower end, and a piezoelectric element integrally provided inside the frame with respect to the frame. And a vibrating piece.
According to the configuration of the second invention, since the piezoelectric vibrating piece can be bonded to the lid substrate and the base substrate using the frame body, there is no need to bond a small piezoelectric vibrating piece inside the package.
[0014]
According to a third aspect of the present invention, in the configuration of the second aspect, the piezoelectric vibrating piece includes a base portion formed integrally with an inner surface of the frame body and a pair of vibrating arms extending in parallel from the base portion. It is a vibration piece, and a groove extending in the length direction is formed in each vibration arm.
According to the configuration of the third invention, the electric field efficiency can be improved by configuring the piezoelectric vibrating piece as a tuning fork type vibrating piece and further forming the groove extending in the length direction in each vibrating arm.
[0015]
According to a fourth aspect of the invention, in the configuration of the third aspect of the invention, the base portion includes a notch portion between a region formed integrally with the inner surface of the frame body and the vibrating arm. To do.
According to the configuration of the fourth aspect of the invention, when the piezoelectric vibrating piece is a tuning fork type vibrating piece, the notch portion is formed in the base portion, thereby effectively preventing the vibration from the vibrating arm from leaking into the base portion. This can prevent the crystal impedance value.
[0016]
In addition, according to the fifth aspect, the above-described object is achieved by a vibrating plate substrate on which a piezoelectric vibrating piece is formed, and a glass base fixed to the vibrating plate substrate with the vibrating plate substrate interposed therebetween. A method of manufacturing a piezoelectric device including a substrate and a lid substrate, wherein the base substrate and the lid substrate having a through hole formed in at least one of them are prepared, a driving electrode is provided on the vibrating piece substrate, and the base substrate In addition, a bonding electrode is provided on a bonding surface with the lid substrate, the vibrating plate substrate, the base substrate and the lid substrate are anodically bonded in the atmosphere, and the through hole is sealed in a vacuum. This is achieved by a method for manufacturing a piezoelectric device.
[0017]
According to the structure of 5th invention, when manufacturing a glass-made base substrate and a lid substrate, a through-hole is provided in either. Then, a bonding electrode is provided on a bonding surface between the base substrate and the lid substrate, and the vibrating piece substrate, the base substrate and the lid substrate are anodically bonded at atmospheric pressure. That is, since anodic bonding is performed at atmospheric pressure, it takes less time to raise the temperature to the temperature required for bonding. Moreover, unlike the prior art, it is not necessary to lower 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. After that, by exhausting the internal gas from the through hole in a vacuum, after the through hole is closed with the sealing material, gas is generated inside and adheres to the piezoelectric vibrating piece. It is possible to effectively prevent adverse effects.
[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 heat-treated in a vacuum at a temperature higher than a reflow temperature of mounting. To do.
According to the configuration of the sixth invention, after the anodic bonding, when 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, the discharge is performed corresponding to the heating temperature. A gas such as water vapor is generated. If this gas component is discharged into a vacuum and the through hole is sealed, even if the piezoelectric device is mounted in a reflow furnace, gas is generated in the mounting process, and the piezoelectric vibrating piece It can be effectively prevented from adhering to and adversely affecting the vibration performance.
[0019]
According to a seventh aspect of the present invention, there is provided a vibrating plate substrate on which a piezoelectric vibrating piece is formed, and a glass base fixed to the vibrating plate substrate with the vibrating plate substrate interposed therebetween. An electronic apparatus using a piezoelectric device including a substrate and a lid substrate, wherein the resonator element substrate, the base substrate, and the lid substrate are anodically bonded to each other, so that an inner side of the base substrate and the lid substrate is provided. The piezoelectric vibrating piece is accommodated in an internal space, and 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, and the through hole is sealed. Achieved by electronic equipment that obtains a clock signal for control by a piezoelectric device in which the internal space is hermetically sealed by filling the material It is.
[0020]
According to an eighth aspect of the present invention, there is provided a resonator element substrate on which a piezoelectric resonator element is formed, and a glass base fixed to the resonator element substrate with the resonator element substrate interposed therebetween. A mobile phone device using a piezoelectric device including a substrate and a lid substrate, wherein the vibration piece substrate, the base substrate, and the lid substrate are anodically bonded to each other so that the inside of the base substrate and the lid substrate A through hole is formed in at least one of the base substrate and the lid substrate to communicate the internal space with the outside, and is sealed in the through hole. According to a mobile phone 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 stopper. , It is achieved.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
1 to 7 show an embodiment of a piezoelectric device of the present invention, FIG. 1 is a schematic exploded perspective view thereof, FIG. 2 is a schematic plan view of a vibrating piece substrate of the piezoelectric device of FIG. 1, and FIG. 2 is a schematic cross-sectional view taken along line AA in FIG. 2, FIG. 4 is a schematic bottom view of the vibrating piece substrate of the piezoelectric device in FIG. 1, FIG. 5 is an end view taken along line BB in FIG. FIG. 7 is a cross-sectional end view taken along the line CC of FIG. 6.
[0022]
In FIG. 1, the piezoelectric device 30 shows an example in which a piezoelectric vibrator is configured. 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 is sized to cover at least the upper opening 36a of the resonator element substrate 36 shown in FIG. 1. In this embodiment, the outer shape of the resonator element substrate 36 is rectangular, and therefore the lid substrate 37 is also rectangular. It is said that. The base substrate 38 has a size that covers at least the lower opening 36b of the resonator element substrate 36 shown in FIG. 1. In this embodiment, since the outer shape of the resonator element substrate 36 is rectangular, the base substrate 38 is also rectangular. It is made into a shape.
[0023]
The lid substrate 37 and the base substrate 38 have the same outer shape, and have the same outer shape as that of the resonator element substrate 36. As shown in FIG. 1, the lid substrate 37 includes a recess 37a, and the base substrate 38 includes a recess 38a.
The lid substrate 37 and the base substrate 38 are fixed so that the concave portions 37a and 38a face each other and the vibration piece substrate 36 is sandwiched therebetween, whereby the concave portions 37a and 38a are described later. An internal space S <b> 2 that accommodates the piezoelectric vibrating piece 32 is formed integrally with the space inside the vibrating piece 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 a gap or space inside. As shown in FIG. 1, the vibrating reed substrate 36 has a lid substrate 37 and a base substrate 38 fixed to the open upper and lower ends, thereby sealing the internal space S2. Yes.
As shown in FIG. 1, the vibration piece substrate 36 does not necessarily have a quadrangular shape, and may be an ellipse having a rounded corner or an oval shape. In the case of the present embodiment, the resonator element substrate 36 is formed as a thin frame having a rectangular shape that is long in one direction as shown in FIG.
[0025]
In particular, in order to form the piezoelectric vibrating piece 32 inside the vibrating piece substrate 36, a piezoelectric material is used. As the piezoelectric material to be used, quartz is suitable as in the present embodiment. In addition to quartz, piezoelectric materials such as lithium tantalate and lithium niobate can be used. In the case of this embodiment, the resonator element substrate 36 forms an outer space and the outer shape of the piezoelectric resonator element 32 by etching a thin crystal plate.
[0026]
The piezoelectric vibrating piece 32 is integrally formed of the same material as that of the vibrating piece substrate 36. In the case of the present embodiment, the piezoelectric vibrating piece 32 is particularly illustrated in order to form a small size and obtain necessary performance. It is made into a shape.
That is, in FIG. 2, the piezoelectric vibrating piece 32 is divided into two forks toward the right in the drawing with the base 51 integrated with the inside of one end of the vibrating piece substrate 36 and the base 51 as a base end. A pair of vibrating arms 34 and 35 extending in parallel with each other and a so-called tuning-fork type piezoelectric vibrating piece, the whole of which is shaped like a tuning fork.
Preferably, the pair of vibrating arms 34 and 35 of the piezoelectric vibrating piece 32 are provided with long grooves 34a and 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 formed in the same manner on the upper and lower surfaces of the vibrating arms 34 and 35, respectively.
[0027]
Thus, the long grooves 34a and 35a extending in the longitudinal direction are formed in the pair of vibrating arms 34 and 35, respectively, and the first excitation electrode 41b and the second excitation electrode 42b are formed in the long grooves 34a and 35a, respectively. Therefore, there is an advantage that the electric field efficiency in the vibrating arms 34 and 35 is improved. In order to avoid the complexity of the illustration, the illustration of the electrodes such as the excitation electrodes 41b and 42b is omitted in FIG.
A notch provided in a reduced width in the width direction of the base 51 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 vibration plate substrate 36 of the piezoelectric vibrating piece 32. Or constricted portions 52, 52 are provided.
Thereby, the leakage of the vibration of the piezoelectric vibrating piece 32 to the base 51 side can be prevented, and the CI (crystal impedance) value can be reduced.
[0028]
As shown in FIG. 2, the first electrode 41 is formed on the upper end surface 36 c 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 around the upper end surface 36c of the resonator element substrate 36, and to the first bonding electrode 41a. Then, the first excitation electrode 41 b is provided that passes through the surface of the base 51 of the piezoelectric vibrating piece 32 and is routed to both side surfaces of the vibrating arm 34 and the upper and lower surfaces of the vibrating arm 35.
Further, as shown in FIG. 4, the second electrode 42 is formed on the lower end surface 36 d of the resonator element substrate 36. As shown by reference numeral 42a in FIG. 4, the second electrode 42 is extended from the second bonding electrode 42a routed around the lower end surface 36d of the resonator element substrate 36, and the second bonding electrode 42a. Then, the second excitation electrode 42 b is provided that passes through the back surface of the base 51 of the piezoelectric vibrating piece 32 and is routed to both side surfaces of the vibrating arm 35 and 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 with the resonator element substrate 36, the lid substrate 37, and the base substrate 38, respectively. The first excitation electrode 41 b and the second excitation electrode 42 b are used to drive the piezoelectric vibrating piece 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 on the surface of the vibrating piece substrate 36 made of, for example, quartz, for example, chromium. A common structure is provided in which a (Cr) layer is formed and a gold (Au) layer is provided thereon.
[0030]
Furthermore, the portion of the first bonding electrode 41a and the second bonding electrode 42a is, for example, an aluminum (Al) layer or a metal coating layer for anodic bonding on the gold layer, It is formed by covering tungsten, silicon, nickel, titanium or the like.
Further, 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 a mounting electrode 45 provided at the end. Similarly, the second bonding electrode 42 a is routed to the bottom surface of the base substrate 38 as a side electrode 46 a on the right side surface in FIG. 6, and the mounting electrode 46 provided at the end of the bottom surface of the base substrate 38. Connected with.
[0031]
As a particularly important configuration, as shown in FIG. 6, in the present embodiment, a through hole 60 that communicates the internal space S <b> 2 and the outside is provided near the center of the lid substrate 37. The through hole 60 is a form in which the two through holes 61 and the through hole 62 communicate with each other, and the outer first hole 62 is formed to have a larger inner diameter than the second hole 61 opened to the inner space S2 side. An outward stepped portion 63 is formed between the first hole 62 and the second hole 61. The through-hole 60 is filled with a sealing material as will be described later, so that the hole is sealed.
[0032]
As shown in FIG. 1, the flat portion 37 c of the lid substrate 37 described with reference to FIGS. 1 and 2 is fixed to the upper end surface 36 c of the resonator element substrate 36, and the lower end surface 36 d of the resonator element substrate 36. The flat portion 38c of the base substrate 38 described in FIG. 1 and FIG.
Specifically, as shown in FIG. 6, the lid substrate 37 and the base substrate 38 are made of a glass-made lid substrate 37 and base substrate 38 with a temperature lower than their softening point. Between the DC power source 39 and the bonding electrodes 41a and 42a, which are bonding films for bonding them to the resonator element substrate 36, so that the bonding electrodes 41a and 42a become anodes. Apply voltage.
In other words, anodic bonding is a method in which the surfaces are brought into close contact with each other in a solid phase, and is a method in which bonding of the surface atoms is generated between surfaces having smooth surfaces. 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 charges formed in the gap between these and the bonding electrodes 41a and 42a and in the vicinity thereof. A voltage applied continuously is applied to the layer. Then, an electrostatic attractive force is generated between the lid substrate 37 and the base substrate 38 and each of the bonding electrodes 41a and 42a, and they are in close contact with each other, and the movement of ions from the glass side to the electrode side is promoted by a strong electric field. Thus, it is considered that a bond is formed by forming a covalent bond with an atom on the electrode side. This process can also proceed reversibly using a reverse voltage.
Thus, the internal space S <b> 2 is sealed in an airtight state by the lid substrate 37 and the base substrate 38 so that the vibration piece substrate 36 is sandwiched 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 showing 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 piece 32 is shown from ST21 to ST24 (previous process).
First, this pre-process will be described.
Both the lid substrate 37 and the base substrate 38 are formed of the same glass material. That is, in order to enable anodic bonding or facilitate anodic bonding, a glass material that easily diffuses ions is selected, and an alkali metal-containing material that is 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 glass substrates of predetermined sizes made of the above-described materials.
Therefore, an anticorrosion 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) in conformity with each outer shape (ST11). Next, the outer shape is formed by etching each of the lid substrate 37 and the base substrate 38 (ST12).
[0035]
Here, what is important 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 near the center of the lid substrate 37. The through hole 60 can be formed simultaneously with the outer shape etching of the lid substrate 37 by removing the 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, by peeling off the corrosion resistant film, the outer shape of the lid substrate 37 and the base substrate 38 described in FIG. 1 and the like is formed (ST13).
Subsequently, a necessary anticorrosion film is formed on the lid substrate 37 and the base substrate 38, and half etching is performed to form the recesses 37a and 38a described in FIG. 1 (ST14).
Finally, with respect to the substrate on which the through hole 60 is provided, the periphery of the hole formed in ST13 is exposed, a corrosion-resistant film is formed on the other part, and half etching is performed, whereby 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 piece 32, for example, using a substrate such as a quartz wafer, a corrosion-resistant film corresponding to the outer shape of the vibrating piece substrate 36 is formed in advance on this substrate (not shown) (ST21). Next, the outer shape of the vibrating piece substrate 36 is formed by etching using an etchant such as hydrofluoric acid (ST22), and the corrosion-resistant film is peeled off (ST23). Next, an electrode required for operation as the piezoelectric vibrating piece 32 and an electrode used as a bonding film for anodic bonding are formed. Such an electrode has, for example, the structure described in FIGS. 2 to 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 technique such as sputtering or vapor deposition.
[0038]
Next, a post process is demonstrated.
As described in FIG. 6, the resonator element substrate 36 is anodically bonded to the lid substrate 37 and the base substrate 38 (ST35).
This anodic bonding process does not need to be performed from the internal space S2 as in the prior art, and can be performed at atmospheric pressure. For this reason, it can be performed according to a temperature profile as shown in FIG. 9, for example.
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 vibration piece substrate 36, these bonding electrodes 41a and 42a. A DC voltage is applied from a DC power supply 39 so that the side becomes an anode.
[0039]
At this time, as shown in FIG. 9, since the time Ht1 for heating from the start to the temperature L1 required for anodic bonding does not need to be out of gas in a vacuum atmosphere as in the prior art, Heating can be performed in a very short time because it is a heating point and does not require a high temperature required for outgassing. That is, the temperature L1 is about 150 degrees Celsius (hereinafter, all temperature displays are “Celsius”). Therefore, the temperature is raised to the temperature L1 (Ht1), and it takes about 3 minutes after the temperature rise until the anodic bonding is completed. Therefore, the time from the start to the completion of the anodic bonding is about 8 minutes.
[0040]
Next, the workpiece is moved to a vacuum chamber (not shown) to be lowered to the temperature L2, and the annealing process is performed by heating again to the temperature L3 from the time Ht3 to the time Ht4 (ST36). The temperature L3 is preferably higher than the reflow temperature performed when the piezoelectric device 30 is mounted. For this reason, it heats to the temperature selected suitably at 260 degreeC or more and about 300 degreeC, for example. This is because this annealing treatment prevents degassing during reflow. Therefore, for example, the temperature is increased to about 300 degrees as the temperature L3, and the gas emitted from the inside of the piezoelectric vibrating piece 32, the lid substrate 37 and the base substrate 38 is discharged from the through hole 60 in the internal space S2 for about 30 minutes.
[0041]
In FIG. 9, hole sealing is performed at time Ht5, which is the final time of temperature L3 (ST37). This hole sealing is performed in the vacuum chamber as follows.
As shown in FIG. 10, the sealing material 70 is disposed 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 falls inside the lid substrate 37. It is preferable that the size does not enter. For this reason, in this 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 joined to the lid substrate 37. Moreover, the thing which does not melt easily with the heating temperature of the reflow process of the piezoelectric device 30 is preferable. Under such conditions, an Au—Sn alloy or an Au—Ge alloy can be used. Moreover, considering the ease of joining with the lid substrate 37 as the sealing material 70, low melting glass etc. can be used.
Then, as shown in FIG. 10, such a sealing material 70 is positioned in the first hole 62 of the through hole 60 and melted by irradiation with laser light LB or the like from the outside. Thereby, the hole sealing is completed by filling the melted sealing material 70 so as to block the through hole 60. Thereafter, the temperature is lowered to Ht6 in FIG. 9 in the vacuum chamber, and the vacuum chamber is taken out. In addition, it is also possible to take out to air | atmosphere immediately after hole sealing and to shorten cooling time further. On the other hand, considering the protection against thermal stress on the package, it is more preferable to lower the temperature in the vacuum chamber as shown in FIG.
Next, the product is diced into individual product sizes (ST38), and necessary inspections are performed to complete the piezoelectric device 30 (ST39).
[0043]
Thus, according to the present embodiment, the through hole 60 is provided in the lid substrate 37. That is, the through-hole 60 is used as a hole for extracting gas from the internal space S2 after anodic bonding of the resonator element substrate 36, the base substrate 38, and the lid substrate 37, respectively. As a result, since anodic bonding can be performed at atmospheric pressure, the time required for raising the temperature to the required temperature L1 can be reduced, and the manufacturing cost can be reduced. Then, after joining, the internal gas is discharged from the through hole 60, and the gas that adversely affects the vibration characteristics of the piezoelectric vibrating piece 32 is removed, so that the vibration performance is not deteriorated. Since it is blocked by the stopper 70, the piezoelectric vibrating piece 32 is properly sealed, and sealing performance is also 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 showing a schematic configuration of a digital mobile phone device as an example of an electronic apparatus using the piezoelectric device according to the above-described 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. CPU (Central
Processing Unit 301 is provided.
In addition to modulation and demodulation of transmission / reception signals, the CPU 301 controls an information input / output unit 302 including an LCD as an image display unit and operation keys for inputting information, and a memory 303 including a RAM and a ROM. 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) incorporated in the CPU 301. ing. The piezoelectric device 30 attached to the CPU 301 may not be a single device such as the piezoelectric device 30 but may be an oscillator that combines the piezoelectric device 30 and 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 the transmitter 307 and the receiver 306. As a result, even if the frequency of the basic clock from the CPU 301 fluctuates due to a change in the environmental temperature, it is corrected by the temperature compensated crystal oscillator 305 and supplied to the transmission unit 307 and the reception unit 306.
[0046]
In this way, by using the piezoelectric device 30 according to the above-described embodiment in an electronic device such as the digital cellular phone device 300 including the control unit, even if it is efficiently produced in a short time at a low cost, The adhesion of the gas does not adversely affect the vibration performance of the piezoelectric vibrating piece 32, and an accurate clock signal can be generated.
[0047]
The present invention is not limited to the above-described embodiment. Each configuration of each embodiment can be appropriately combined or omitted, and can be combined with other configurations not shown.
In particular, the electrode routing structure of the piezoelectric vibrating piece is not limited to the example described in the above embodiment, and various structures can be employed.
In addition, the present invention can be applied to all piezoelectric devices regardless of the names of piezoelectric vibrators, piezoelectric oscillators, etc., as long as the piezoelectric vibrating reed is accommodated 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 vibrating piece substrate of the piezoelectric device of FIG.
FIG. 3 is a schematic cross-sectional view taken along line AA in FIG.
4 is a schematic bottom view of a vibrating piece substrate of the piezoelectric device of FIG. 1. FIG.
FIG. 5 is a cross-sectional end view taken along the line BB in FIG. 1;
6 is a schematic cross-sectional view showing a state of anodic bonding of the piezoelectric device of FIG. 1. FIG.
FIG. 7 is a cross-sectional end view taken along the line CC of FIG.
FIG. 8 is a flowchart showing an embodiment of a method for manufacturing a piezoelectric device of the present invention.
9 is a graph showing an example of a temperature profile of anodic bonding and annealing treatment in the manufacturing process of FIG.
10 is an explanatory view showing a state of hole sealing in the manufacturing process of FIG. 8. FIG.
FIG. 11 is a diagram 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.
13 is a schematic cross-sectional view of the piezoelectric device of FIG.
FIG. 14 is a flowchart showing a method for manufacturing the piezoelectric device of FIG. 12;
15 is a graph showing a temperature profile of anodic bonding and annealing treatment in the manufacturing process of FIG. 14;
[Explanation of symbols]
30 ... Piezoelectric device, 32 ... Piezoelectric vibrating piece, 36 ... Vibrating piece substrate, 37 ... Lid substrate, 38 ... Base substrate, 41a, 42a ... Joining electrode, 41b ... First excitation electrode, 42b ... second excitation electrode, 51 ... base.

Claims (8)

A piezoelectric device comprising: a resonator element substrate on which a piezoelectric resonator element is formed; and a glass base substrate and a lid substrate that are respectively fixed to the resonator element substrate with the resonator element substrate interposed therebetween.
The piezoelectric vibrating piece is accommodated in an internal space inside the base substrate and the lid substrate by anodically bonding the vibrating piece substrate, the base substrate and the lid substrate,
Further, 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, and the internal space is sealed by filling the through hole with a sealing material. A piezoelectric device, wherein the piezoelectric device is sealed. The vibration piece substrate includes: a frame body having an open upper end and a lower end; and a piezoelectric vibration piece integrally provided inside the frame body with respect to the frame body. The piezoelectric device described. The piezoelectric vibrating piece is a tuning fork type vibrating piece having a base portion integrally formed on the inner surface of the frame body and a pair of vibrating arms extending in parallel from the base portion. The piezoelectric device according to claim 2, wherein a groove extending in a direction is formed. The piezoelectric device according to claim 3, wherein the base portion includes a notch portion between a region formed integrally with an inner surface of the frame body and the vibrating arm. A method of manufacturing a piezoelectric device comprising a resonator element substrate on which a piezoelectric resonator element is formed and a glass base substrate and a lid substrate that are each fixed to the resonator element substrate with the resonator element substrate interposed therebetween,
Preparing the base substrate and the lid substrate having a through-hole formed in at least one of them,
A driving electrode is provided on the vibration piece substrate, and a bonding electrode is 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 atmosphere,
Furthermore, the through-holes are sealed in a vacuum. 6. The method of manufacturing a piezoelectric device according to claim 5, wherein after the anodic bonding and before the hole sealing, the piezoelectric vibrating piece is heat-treated in a vacuum at a temperature higher than a reflow temperature of mounting. An electronic apparatus using a vibrating element substrate on which a piezoelectric vibrating piece is formed, and a piezoelectric device including a glass base substrate and a lid substrate that are fixed to the vibrating piece substrate with the vibrating plate substrate interposed therebetween. And
The piezoelectric vibrating piece is accommodated in an internal space inside the base substrate and the lid substrate by anodically bonding the vibrating piece substrate, the base substrate and the lid substrate,
Further, 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, and the internal space is sealed by filling the through hole with a sealing material. An electronic apparatus characterized in that a clock signal for control is obtained by a piezoelectric device sealed in the housing. A mobile phone device using a piezoelectric resonator device including a resonator element substrate on which a piezoelectric resonator element is formed and a glass base substrate and a lid substrate that are fixed to the resonator element substrate with the resonator element substrate interposed therebetween. There,
The piezoelectric vibrating piece is accommodated in an internal space inside the base substrate and the lid substrate by anodically bonding the vibrating piece substrate, the base substrate and the lid substrate,
Further, 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, and the internal space is sealed by filling the through hole with a sealing material. A cellular phone device characterized in that a clock signal for control is obtained by a piezoelectric device sealed in the housing.

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