JP2008079211A - Piezoelectric device, temperature controlled piezoelectric oscillator, and manufacturing method of piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize an oscillator, to attain reduction in power consumption, and further to provide a temperature controllable oscillator with superior temperature characteristics. <P>SOLUTION: A temperature controlled piezoelectric oscillator 1 mounts a SAW device 4 on the inner bottom surface of a package 3, with a recessed portion 2 formed inside so that a second surface, with a heating object integrally formed, faces the inner bottom surface of the package 3, mounts an IC chip 5 with a built-in temperature sensor, a temperature control circuit and an oscillation circuit side by side in the SAW device 4, and is air-tightly sealed by a lid 6, after prescribed wire bonding. The temperature-controlled piezoelectric oscillator 1 heats the SAW device 4 to a prescribed temperature by using the temperature control circuit built in the IC chip 5. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a temperature-controllable piezoelectric device having excellent temperature characteristics, a temperature-controlled piezoelectric oscillator, and a method for manufacturing a piezoelectric device, as well as miniaturization and low power consumption.

A crystal oscillator that supplies an oscillation signal with a stable frequency is widely used as a clock source in communication equipment, electronic equipment, etc., but its frequency characteristics vary by several tens of ppm due to changes in ambient temperature. In many cases, a temperature-controlled crystal oscillator having a further improved value is used.
In order to further improve the stability of the oscillation frequency of the crystal oscillator, the temperature controlled crystal oscillator uses a thermostatic chamber as a measure not affected by the ambient temperature. For example, by housing the crystal resonator and the electrical components that constitute the oscillation circuit in a thermostat bath made of a metal block, and using a heater for heating, the thermostat bath is heated to, for example, about 70 ° C. and kept constant, The frequency fluctuation due to the ambient temperature fluctuation is suppressed.
As a conventional example of such a temperature controlled crystal oscillator, there is Patent Document 1 or the like.

On the other hand, with the recent increase in the oscillation frequency, an oscillator using a surface acoustic wave (SAW) device that can handle a high frequency is used as compared with an oscillator using a crystal resonator. A temperature-controlled SAW oscillator connects a SAW resonator to an oscillation circuit instead of a crystal resonator, and heats the SAW resonator or oscillation circuit using a heater for heating in order to increase the stability of the oscillation frequency of the SAW oscillator. Thus, the ambient temperature is kept constant. In the SAW resonator, reflectors are provided on both sides of the interdigital transducer (IDT), and the surface wave energy propagating toward the outside is reflected to confine the surface wave energy in the IDT portion, thereby obtaining a high Q resonance characteristic. Is.
As a conventional example of such a temperature controlled SAW oscillator, there is Patent Document 2 and the like. The temperature-controlled SAW oscillator of Patent Document 2 uses (Si + Zn) as the base substrate of the SAW device, and the temperature-controlled SAW oscillator is miniaturized by making the oscillation circuit, the control circuit, etc. into an IC, and the temperature control heater is consumed. The power is reduced.
Japanese Patent Laid-Open No. 7-50523 JP 2006-67080 A

However, in the temperature controlled crystal oscillator using the crystal resonator of Patent Document 1, a heating element for temperature control is attached to a case in which a crystal resonator element is enclosed, and an oscillation circuit, a control circuit, and the like are provided with a metal heat insulating case. It is the structure which sealed the whole including. Therefore, it is difficult to reduce the size of the temperature controlled crystal oscillator, the thermal efficiency applied to the crystal resonator is poor, and it is not suitable for reducing power consumption.
On the other hand, the temperature-controlled SAW oscillator using the SAW device of Patent Document 2 uses (Si + Zn) as the substrate of the SAW device, and the temperature characteristics of the SAW device itself are poor, and it is large when controlling the temperature of the SAW oscillator. With difficulty.

  The present invention has been made in order to solve the above-described problems, and is a piezoelectric device capable of downsizing an oscillator and reducing power consumption, and having excellent temperature characteristics and capable of temperature control, and temperature control. An object of the present invention is to provide a piezoelectric oscillator and a method for manufacturing a piezoelectric device.

In order to achieve the above object, a piezoelectric device, a temperature-controlled piezoelectric oscillator, and a method for manufacturing a piezoelectric device according to the present invention have the following configurations.
The piezoelectric device according to the present invention is a piezoelectric device in which a predetermined electrode is formed on one surface of a base substrate, and the heat generation formed between the two heat generating electrodes formed on the other surface of the base substrate and the heat generating electrode. And the base substrate can be heated to a desired temperature by applying a voltage to the heating electrode.
According to this, since the heating element is directly formed on the other surface of the piezoelectric device, the rise time after turning on the power when the base substrate is heated to stabilize the temperature characteristics of the piezoelectric device is shortened and temperature control is easy. This makes it possible to reduce the size of an oscillator using a piezoelectric device.

The piezoelectric device according to the present invention is characterized in that a quartz substrate is used as a base substrate. According to this, since the quartz substrate is used as the base substrate of the piezoelectric device, it is possible to secure stable piezoelectric device characteristics having excellent temperature characteristics.
In addition, the piezoelectric device according to the present invention is characterized in that an interdigital electrode is formed on one surface of a base substrate, and a SAW resonator including reflectors on both sides of the interdigital electrode is formed. According to this, since the SAW resonator is used as the piezoelectric device, stable oscillation characteristics can be obtained even at a high frequency of, for example, 100 MHz or higher when configuring the oscillator.
In addition, the piezoelectric device according to the present invention is characterized in that the heating element formed on the other surface is a metal film using heating paint or nichrome.
According to this, since a metal film using heat-generating paint or nichrome is used as a heating element integrally formed with the piezoelectric device, it is possible to provide a heating element with little secular change without increasing the thickness of the piezoelectric device. Is possible.

In addition, the piezoelectric device according to the present invention is formed by forming two electrodes on one surface of the base substrate for connection to an external circuit by wire bonding, and electrically connecting and fixing the external circuit using a conductive adhesive. For this purpose, the heat generating electrode is formed on the other surface of the base substrate.
In addition, the piezoelectric device according to the present invention has two electrodes provided with bumps for electrically connecting and fixing an external circuit on one surface of the base substrate, and for connecting to the external circuit by wire bonding. Two electrodes are formed on the other surface of the base substrate.
According to this, as a method for mounting a piezoelectric device on a package, an adhesive fixing method using a conductive adhesive, a connection fixing method using a bump, or a connection method using wire bonding is adopted. Can be mounted on a package, and the piezoelectric device can be miniaturized when used as an oscillator.

The temperature controlled piezoelectric oscillator according to the present invention includes a package having a recess therein, an element mounting pad formed on the inner bottom surface of the package, an IC chip incorporating a temperature sensor, a temperature control circuit, and an oscillation circuit, The heating electrode formed on the other surface of the base substrate of the piezoelectric device and the element mounting pad are connected and fixed using a conductive adhesive, and the electrode formed on the one surface of the piezoelectric device and the IC chip It is characterized in that the formed electrode is connected via a printed pattern provided on the inner bottom surface of the package.
According to this, there are two components of the temperature-controlled piezoelectric oscillator: a piezoelectric device and an IC chip, and since the temperature control is performed by directly heating the base substrate of the piezoelectric device, the temperature-controlled piezoelectric oscillator can be downsized. In addition, power consumption can be reduced.

The temperature controlled piezoelectric oscillator according to the present invention includes a package having a recess therein, an element mounting pad formed on the inner bottom surface of the package, an IC chip incorporating a temperature sensor, a temperature control circuit, and an oscillation circuit, Are connected and fixed to the element mounting pad using bumps provided on one side of the base substrate of the piezoelectric device, and the IC chip is bonded and fixed on the other side of the base substrate, and further provided on the other side of the base substrate. It is characterized in that the electrodes provided on the IC chip are connected to each other.
According to this, there are two components of the temperature controlled piezoelectric oscillator: a piezoelectric device and an IC chip, and the temperature control is performed by directly heating the base substrate of the piezoelectric device. As a result, power consumption can be reduced. Furthermore, since the IC chip is mounted on the upper surface of the piezoelectric device, the temperature sensor built in the IC chip and the heating element formed on the piezoelectric device are close to each other, and the temperature at which the piezoelectric W device is heated, The temperature difference from the temperature detected by the temperature sensor is reduced, and furthermore, highly accurate temperature control is possible, and the stability of the oscillation frequency is improved. Further, the temperature controlled piezoelectric oscillator can be further downsized.

The temperature controlled piezoelectric oscillator according to the present invention includes a package having a recess therein, an element mounting pad formed on the inner bottom surface of the package, an IC chip incorporating a temperature sensor, a temperature control circuit, and an oscillation circuit, Are connected and fixed to the element mounting pad using bumps provided on one side of the base substrate of the piezoelectric device, and the IC chip is bonded and fixed on the other side of the base substrate, and further provided on the other side of the base substrate. It is characterized in that the electrodes provided on the IC chip are connected to each other.
According to this, there are two components of the temperature-controlled piezoelectric oscillator, ie, the piezoelectric device and the IC chip, and the temperature control piezoelectric oscillator can be downsized because the base substrate of the piezoelectric device is directly heated for temperature control. In addition, power consumption can be reduced.

The method for manufacturing a piezoelectric device according to the present invention includes a step of forming at least two heat generating electrodes on the base substrate base material, a step of forming a heating element between the heat generating electrodes, and a desired base substrate base material. The method includes a step of forming an electrode pattern, a step of adjusting a frequency by thinning the thickness of the electrode pattern, and a step of dividing the base substrate base material into a plurality of piezoelectric devices.
According to this, as a manufacturing process of the piezoelectric device, it is possible to easily manufacture the piezoelectric device without greatly changing the conventional manufacturing process, and the initial investment related to the manufacturing equipment is reduced, and the piezoelectric device is reduced. Contributes to cost reduction of the used oscillator. Further, if the metal films formed on both surfaces of the piezoelectric device are unified as, for example, aluminum, the processes can be made common to the first manufacturing process and the second manufacturing process.

Hereinafter, the present invention will be described in detail based on the illustrated embodiments.
FIG. 1 is a structural diagram showing a first embodiment of a temperature-controlled piezoelectric oscillator according to the present invention. FIG. 1 (a) is a top view of the temperature-controlled piezoelectric oscillator with its lid removed, and FIG. b) shows a longitudinal sectional view thereof. In the temperature controlled piezoelectric oscillator shown in FIG. 1, a SAW device is used as a piezoelectric device used in an oscillation circuit, and the SAW device uses a quartz substrate as a base substrate. In addition, a SAW resonator is formed on the first surface (one surface) of the SAW device, and a heating element is integrally formed on the second surface (other surface) of the SAW device. The resonator can be heated to a predetermined temperature.
That is, in the temperature-controlled piezoelectric oscillator 1 according to the first embodiment, the second surface in which the heating element is integrally formed on the inner bottom surface of the package 3 in which the recess 2 is formed is the inner bottom surface of the package 3. The IC chip 5 having the temperature sensor, the temperature control circuit, and the oscillation circuit mounted side by side is mounted on the SAW device 4 and subjected to predetermined wire bonding, and then the lid 6 is mounted. This is a hermetically sealed structure.

On the inner bottom surface of the package 3 made of an insulator such as ceramic, an element mounting pad 8 for connecting and fixing the SAW device 4 with the conductive adhesive 7, an electrode 9 provided on the SAW device 4, and an IC chip An electrode 11 for connecting the electrode 10 provided in 5 by wire bonding and a predetermined print pattern 12 are formed. In FIG. 1, the mounting terminals provided in the package 3 and the print pattern derived to the mounting terminals are omitted.
In the temperature controlled piezoelectric oscillator 1 of the present embodiment, the SAW device 4 is heated to a predetermined temperature by the temperature control circuit built in the IC chip 5. As a result, the temperature-controlled voltage oscillator 1 having a simple structure and excellent in miniaturization can be realized.

Next, the structure of the SAW device 4 will be described.
FIG. 2 is a structural diagram showing the first embodiment of the SAW device according to the present invention, and FIG. 2 (a) is a diagram showing the structure of the first surface (one surface) of the SAW device, FIG. FIG. 2B is a diagram showing the structure of the second surface (other surface) of the SAW device, and FIG. 2C is a side view of the SAW device in the short side direction.
In the SAW device 4, a quartz substrate is used as a base substrate 13, and an IDT 14 is placed at the center on the first surface of the SAW device 4, and a SAW resonator 16 is formed on both sides of which a reflector 15 is arranged. In addition, two wire bonding electrodes 9 for connecting to the IDT 14 and connecting to an oscillation circuit built in the IC chip 5 are provided.

  The SAW resonator 16 realizes a resonator having a high Q by confining the SAW excited by the IDT 14 between both reflectors 15. Further, since the SAW resonator 16 uses a quartz substrate as the base substrate 13, it has superior temperature characteristics as compared with the case where (Si + Zn) is used as the base substrate 13, and the SAW resonator 16 is provided in the oscillation loop of the oscillator. When used, it becomes possible to cope with a high frequency exceeding 100 MHz.

On the other hand, on the second surface of the SAW device 4, two heating electrodes for electrically connecting to the element mounting pads 8 provided on the package 3 and fixing the SAW device 4 along the opposing sides. 17 is provided.
Further, a heating element 18 such as a heating paint is applied between the heating electrodes 17 including a part of the heating electrode 17, and a predetermined voltage is applied by a voltage applied between the two heating electrodes 17. It has a structure that generates heat with temperature. As the exothermic paint, those that are less likely to deteriorate due to secular change are desirable. For example, a conductive exothermic paint in which graphite powder and metal powder as a carbon-based material are mixed in a binder such as an epoxy resin can be applied.

  The SAW resonator 16 is an element that obtains a desired function by SAW propagating on the first surface of the quartz substrate. Even if the heating element 18 is formed integrally on the second surface of the SAW device 4, the SAW resonator 16 is SAW. The function of the resonator 16 is not affected. In FIG. 2, the two heat generating electrodes 17 are provided along the long side on the second surface of the SAW device, but the two heat generating electrodes are provided on the short side on the second surface of the SAW device. The heating element may be integrated and formed between two heating electrodes including a part of the heating electrode.

Next, the operation of the temperature controlled piezoelectric oscillator 1 will be described.
The IC chip 5 includes an oscillation circuit, and includes an SAW resonator 16 provided in the SAW device 4 to form an oscillation loop and oscillate at a predetermined frequency. On the other hand, a heating element 18 is formed in the SAW device 4, and the heating temperature is controlled by a temperature control circuit built in the IC chip 5. Further, the IC chip 5 is provided with a temperature sensor, detects the internal temperature of the ceramic package 3, and changes the voltage output from the temperature control circuit, thereby controlling the current flowing through the heating element 18 and SAW resonance. The child 16 is heated to maintain a predetermined temperature.

The temperature characteristic of the SAW resonator 16 has a quadratic curve, and the change in frequency due to temperature fluctuations near the vertex of the quadratic curve is gentle. Therefore, for example, when the temperature characteristic of the SAW resonator 16 is designed so that the temperature near the vertex of the quadratic curve is about 70 ° C., and the SAW resonator 16 is heated to 70 ° C. using the heating element 18, Even if the internal temperature of the package 3 changes, the change in the oscillation frequency of the oscillation circuit is gradual, and the temperature controlled piezoelectric oscillator 1 with better temperature characteristics can be realized.
Further, since the SAW resonator 16 that greatly affects the fluctuation of the oscillation frequency is directly heated by the heating element 18, the rise time of the temperature-controlled piezoelectric oscillator 1 after the power is turned on, that is, the oscillation frequency of the temperature-controlled piezoelectric oscillator 1 is stabilized. Time is also shortened.

Next, a second embodiment will be described.
FIG. 3 is a structural view showing a second embodiment of the temperature controlled piezoelectric oscillator according to the present invention. FIG. 3 (a) shows a top view of the temperature controlled piezoelectric oscillator with the lid removed, and FIG. b) shows a longitudinal sectional view thereof. Also in the second embodiment, as in the first embodiment, a SAW device is used as the piezoelectric device used in the oscillation circuit, and the SAW device uses a quartz substrate as a base substrate. Further, a heating element is formed integrally on the second surface of the SAW resonator so that the SAW resonator can be heated to a predetermined temperature. The second embodiment is characterized in that an IC chip is mounted on the top of the SAW device.

  The temperature-controlled piezoelectric oscillator 19 has the SAW device 22 on the inner bottom surface of the package 21 in which the recess 20 is formed, and the surface (first surface) on which the SAW resonator is formed faces the inner bottom surface of the package 21. It is mounted using bumps. Furthermore, an IC chip 23 incorporating a temperature sensor, a temperature control circuit and an oscillation circuit is mounted on the upper surface of the surface (second surface) on which the heating element of the SAW device 22 is integrally formed. After wire bonding, the lid 24 is hermetically sealed.

On the surface of the inner bottom surface of the package 21 made of an insulator such as ceramic, the SAW device 22 is connected and fixed by bumps 25, and an element mounting pad 27 for connecting to the electrodes 26 provided on the IC chip 23 by wire bonding. Is formed. In FIG. 3, the mounting terminals provided in the package 21 and the print pattern derived to the mounting terminals are omitted.
In the temperature controlled piezoelectric oscillator 19 of the present embodiment, the IC chip 23 is mounted on the upper surface of the SAW device 22 as viewed in the figure, and the SAW device 22 is heated to a predetermined temperature by the temperature control circuit built in the IC chip 23. I tried to do it. As a result, the oscillator has a simple structure, and it is possible to realize the temperature-controlled voltage oscillator 19 that is further downsized than the first embodiment.

Next, the structure of the SAW device 22 will be described.
FIG. 4 is a structural diagram showing a second embodiment of the SAW device according to the present invention, FIG. 4 (a) is a diagram showing the structure of the first surface of the SAW device, and FIG. 4 (b) is a SAW device. FIG. 4C is a side view showing the structure of the second surface of the device, and FIG. 4C is a side view of the SAW device in the short side direction.
In the SAW device 22, a quartz substrate is used as a base substrate 28, an IDT 29 is placed at the center on the first surface of the SAW device 22, and a SAW resonator 31 is formed on both sides of which a reflector 30 is arranged.
Similar to the SAW resonator 15 described in the first embodiment, the SAW resonator 31 realizes a resonator having a high Q by confining the SAW excited by the IDT 29 between both reflectors 30. .

In addition, electrodes 31 and bumps 25 are provided to connect to the IDT 29 and to be fixed to the package 21. In FIG. 4, one bump is provided for one electrode, but a plurality of bumps may be provided for one electrode.
In the second embodiment, the first surface on which the SAW resonator 31 is formed is fixed to the element mounting pad 27 formed on the inner bottom surface of the package 21 using the bumps 25.
Also in the second embodiment, since the SAW resonator 31 uses a quartz substrate as the base substrate 28, the SAW resonator 31 has excellent temperature characteristics as compared with the case where (Si + Zn) is used as the base substrate 28, and the oscillation of the oscillator. When a SAW resonator is used for the loop, a high frequency exceeding 100 MHz can be supported.

On the other hand, on the second surface of the SAW device 4, an electrode 26 provided on the IC chip 23 and two heat generating electrodes 33 for connection by wire bonding are provided along opposing sides.
In addition, a heating element 34 such as a heating paint is applied between the two heating electrodes 33 including a part of the heating electrode 33, and a voltage applied between the two heating electrodes 33 is applied. It has a structure that generates heat at a predetermined temperature.
As the heat-generating paint, a paint with little deterioration due to secular change is required as in the first embodiment. The SAW resonator 31 is an element that obtains a desired function by the SAW propagating on the first surface of the quartz substrate. Even if the heating element 34 is integrally formed on the second surface of the SAW device 22, the SAW resonator 31 is resonated. The function of the child 31 is not affected. In FIG. 4, the two heat generating electrodes 33 are provided along the short side on the second surface of the SAW device, but the two heat generating electrodes are provided on the long side on the second surface of the SAW device. The heating element may be integrated and formed between two heating electrodes including a part of the heating electrode.

Next, since the operation of the temperature controlled piezoelectric oscillator 19 is the same as that of the temperature controlled piezoelectric oscillator 1 in the first embodiment described above, a description thereof will be omitted, but in the second embodiment, the SAW device 22 is illustrated in FIG. The IC chip 23 was mounted in contact with the upper surface.
Accordingly, the temperature sensor built in the IC chip 23 and the heating element 34 formed integrally with the SAW device 22 are close to each other, and the temperature at which the SAW device 22 is heated and the temperature detected by the temperature sensor. And the temperature difference can be reduced, and the temperature can be controlled with high accuracy, and the stability of the oscillation frequency is improved.

Next, a modified example of the heating element integrally formed with the SAW device will be described.
FIG. 5 is a structural diagram showing a third embodiment of the SAW device according to the present invention, FIG. 5A is a diagram showing the structure of the first surface of the SAW device, and FIG. 5B is a SAW device. It is the figure which showed the structure of the 2nd surface of a device.
The third embodiment is a modification of the structure of the second surface of the first embodiment of the SAW device. The SAW device 35 has a heating element 37 between two heating electrodes 36, for example, of nichrome. Such a heating wire pattern is integrally formed. The heating element generates heat when an electric current is passed, and even if it is formed on the back surface of a piezoelectric device such as a SAW device, a heating element that does not become thick as a whole SAW device and does not interfere with the mounting process is preferable.

  In the case of nichrome, after a nichrome metal film is formed on the second surface of the quartz substrate by vapor deposition, a desired pattern is formed by photolithography or the like. The heating wire pattern made of nichrome is less deteriorated due to secular change, and a stable temperature-controlled piezoelectric oscillator can be realized. Note that the third embodiment can be realized even with a structure similar to that of the SAW device shown in FIG. In FIG. 5, the two heat generating electrodes 36 are formed in the long side direction on the second surface of the SAW device. However, the heat generating element is integrally formed between the two heat generating electrodes. May be.

Next, a method for manufacturing a SAW device according to the present invention will be described.
FIG. 6 is a flowchart showing a first manufacturing process of the SAW device according to the present invention. FIG. 7 is a flowchart showing a second manufacturing process and a third manufacturing process of the SAW device according to the present invention. The flowcharts shown in FIG. 6 to FIG. 8 describe the first embodiment of the SAW device described above. The manufacturing process is mainly composed of three processes. The first manufacturing process is a manufacturing process for forming a heating element on the second surface of the quartz substrate, and the second manufacturing process is on the first surface of the quartz substrate. The manufacturing process for forming the SAW resonator and the third manufacturing process include a manufacturing process in which a plurality of SAW devices formed on the quartz substrate base material in the first manufacturing process and the second manufacturing process are cut into individual SAW devices. It is. Although not specifically described in the first manufacturing process and the second manufacturing process, the crystal substrate used in the first manufacturing process and the second manufacturing process is a crystal substrate base material for forming a plurality of SAW devices. It is.

The first manufacturing process will be described. First, the quartz substrate is cleaned by slightly etching both surfaces of the quartz substrate using an etching solution such as sulfuric acid (step A1).
Next, a metal film is formed on the second surface of the quartz substrate by depositing, for example, an aluminum film with a predetermined thickness (step A2).
Further, after applying a resist over the entire surface of the metal film (step A3), a photomask for forming a desired heat-generating electrode is installed, and the resist film is exposed by an exposure apparatus (step A4).

Next, the process proceeds to a development step, and the resist in the area where light is blocked by the photomask is washed away (step A5).
Next, etching is performed using an etching solution to remove the metal film region where the resist film is not formed (step A6). Further, when the resist film is stripped using the resist stripping solution, only the metal film that forms the two heat generating electrodes remains, and two heat generating electrodes are completed on the second surface of the quartz substrate (step A7). .
Finally, heat generating paint is applied between the heat generating electrodes including a part of the heat generating electrode (step A8), and the first manufacturing process is completed.

Next, the second manufacturing process will be described. First, a metal film is formed on the first surface of the quartz substrate by depositing, for example, an aluminum film with a predetermined thickness (step B1).
Further, after applying a resist over the entire surface of the metal film (step B2), a photomask for forming an IDT and a reflector constituting the SAW resonator is installed, and the resist film is exposed by an exposure apparatus ( Step B3).
Next, the process proceeds to a development step, where the resist in the area where light is blocked by the photomask is washed away (step B4).
Next, etching is performed using an etching solution to remove the metal film region where the resist film is not formed (step B5).
Further, when the resist film is stripped using the resist stripping solution, only the metal film that forms the desired IDT and reflector remains, and the SAW resonator is completed on the first surface of the quartz substrate (step B6). Finally, the completed SAW resonator is immersed in an etchant to adjust the frequency by thinning the thickness of the metal film (step B7), and the second manufacturing process ends.

  Next, the third manufacturing process will be described. The third manufacturing process is a manufacturing process in which a plurality of SAW devices completed on the quartz substrate base material by the first manufacturing process and the second manufacturing process are cut into individual SAW devices, such as dicing. (Step C1).

Next, the manufacturing process of the SAW device according to the present invention will be described with reference to the structural drawings.
FIG. 8 is a structural view showing a first manufacturing process of the SAW device according to the present invention. FIG. 9 is a structural diagram showing a second manufacturing process and a third manufacturing process of the SAW device according to the present invention.
The first manufacturing process will be described with reference to the structural diagram shown in FIG. First, A1 is a state in which the quartz substrate 38 is cleaned by slightly etching both surfaces of the quartz substrate 38 using an etching solution such as sulfuric acid. A2 is a state in which the metal film 39 is formed on the second surface of the quartz substrate 38 with a predetermined thickness, for example, by depositing an aluminum film or the like. In A5, after applying a resist over the entire surface of the metal film 39, a photomask for forming a heating electrode was installed, the resist film 40 was exposed by an exposure device, and light was blocked by the photomask. This is a state in which the resist in the region is washed away. A6 shows a state in which etching is performed using an etching solution to remove a region of the metal film where the resist film 40 is not formed. The resist film 40 covers the metal film 39 constituting a desired heat-generating electrode. It is in the state. A7 peeled off the resist film 40 using a resist stripping solution, leaving only the metal film 39 forming the two heat generating electrodes, and completed the two heat generating electrodes 41 on the second surface of the quartz substrate. State. A8 shows a state in which the heat generating paint 42 is applied between the heat generating electrodes including a part of the heat generating electrode 41.

  Next, the second manufacturing process and the third manufacturing process will be described with reference to the structural diagram shown in FIG. First, B1 shows a state in which the metal film 43 is formed on the first surface of the quartz substrate 38 by depositing, for example, an aluminum film with a predetermined thickness. In B4, a resist is applied to the entire surface of the metal film 43, a photomask for forming an IDT and a reflector constituting the SAW resonator is installed, the resist film 44 is exposed by an exposure device, and a photomask is formed. A state in which the resist in a region where light is blocked by the mask is washed away is shown. B5 shows a state in which etching is performed using an etching solution and a region of the metal film where the resist film 44 is not formed is deleted. The resist film 44 is formed on the metal film 43 constituting a desired IDT or reflector. It is in a covered state. In B6, the resist film is stripped using a resist stripping solution, leaving only the metal film that forms the desired IDT 45 and reflector 46, and the SAW resonator is completed on the first surface of the quartz substrate 38. is there.

Next, the third manufacturing process will be described.
C1 is a manufacturing process in which a plurality of SAW devices completed on the quartz substrate base material by the first manufacturing process and the second manufacturing process are cut into individual SAW devices, and dicing is performed at the position of the dotted line shown in FIG. Cut by means such as.

  Although the temperature controlled piezoelectric oscillator using the SAW device has been described above, the piezoelectric device is not limited to the SAW device, and the function of the piezoelectric device is limited to only one surface even if it is another piezoelectric device. If the other side is not affected, the heating element can be integrally formed on the other side, and the present invention can be applied.

1 is a structural diagram showing a first embodiment of a temperature-controlled piezoelectric oscillator according to the present invention. 1 is a structural diagram showing a first embodiment of a SAW device according to the present invention. FIG. 5 is a structural diagram showing a second embodiment of a temperature controlled piezoelectric oscillator according to the present invention. FIG. 3 is a structural diagram showing a second embodiment of a SAW device according to the present invention. FIG. 6 is a structural diagram showing a third embodiment of a SAW device according to the present invention. It is a flowchart which shows the 1st manufacturing process of the SAW device which concerns on this invention. It is a flowchart which shows the 2nd manufacturing process and 3rd manufacturing process of the SAW device which concern on this invention. It is a structural view showing a first manufacturing process of the SAW device according to the present invention. It is a structural diagram showing a second manufacturing process and a third manufacturing process of the SAW device according to the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,19 ... Temperature control piezoelectric oscillator, 2, 20 ... Recess 3, 3, 21 ... Package 4, 22, 35 ... SAW device 5, 23 ... IC chip, 6, 24 ... Cover, 7 ... Conductive adhesive 8, 27 ... Element mounting pads, 9, 10, 11, 26, 32, 36 ... Electrodes, 12 ... Print pattern, 13, 28 ... Base substrate, 14, 29, 45 ... IDT, 15, 30, 46 ... Reflection 16, 31 ... SAW resonator, 17, 33, 41 ... heating electrode, 18, 34, 37 ... heating element, 25 ... bump, 38 ... quartz substrate, 39, 43 ... metal film, 40, 44 ... resist Film, 42 ... exothermic paint

Claims (10)

A piezoelectric device having a predetermined electrode formed on one side of a base substrate,
Two heating electrodes formed on the other surface of the base substrate, and a heating element formed between the heating electrodes, and applying a voltage to the heating electrode brings the base substrate to a desired temperature. A piezoelectric device configured to be heatable.   The piezoelectric device according to claim 1, wherein a quartz substrate is used as the base substrate.   3. The piezoelectric device according to claim 1, wherein an interdigital electrode and a SAW resonator including reflectors on both sides of the interdigital electrode are formed on one surface of the base substrate. device.   4. The piezoelectric device according to claim 1, wherein the heating element formed on the other surface of the base substrate is a metal film using heat-generating paint or nichrome. 5. Two electrodes for connecting to an external circuit by wire bonding are formed on one side of the base substrate,
5. The heating electrode for electrically connecting and fixing to the external circuit using a conductive adhesive is formed on the other surface of the base substrate. The piezoelectric device according to one item. Forming two electrodes on one surface of the base substrate, which are electrically connected to an external circuit and provided with bumps for fixing;
5. The piezoelectric device according to claim 1, wherein two electrodes for connection to the external circuit by wire bonding are formed on the other surface of the base substrate. 6. A temperature-controlled piezoelectric oscillator using the piezoelectric device according to any one of claims 1 to 5,
A package having a recess therein; an element mounting pad formed on an inner bottom surface of the package; and a temperature sensor, a temperature control circuit, and an IC chip incorporating an oscillation circuit, and the base substrate of the piezoelectric device The heating electrode formed on the other surface of the device and the element mounting pad are connected and fixed using a conductive adhesive, and the electrode formed on the one surface of the piezoelectric device and the electrode formed on the IC chip are A temperature controlled piezoelectric oscillator characterized in that it is connected via a printed pattern provided on the inner bottom surface of the package. A temperature controlled piezoelectric oscillator using the piezoelectric device according to any one of claims 1 to 4 and claim 6,
A package having a recess therein; an element mounting pad formed on an inner bottom surface of the package; and a temperature sensor, a temperature control circuit, and an IC chip incorporating an oscillation circuit, and the base substrate of the piezoelectric device The bumps provided on one surface of the base substrate are connected and fixed to the element mounting pad, the IC chip is bonded and fixed on the other surface of the base substrate, and the electrodes and the IC provided on the other surface of the base substrate are also fixed. A temperature-controlled piezoelectric oscillator characterized by connecting an electrode provided on a chip.   By detecting the internal temperature of the piezoelectric device with a temperature sensor built in the IC chip and operating the temperature control circuit, the current flowing through the heating element formed in the piezoelectric device is controlled, and the base substrate The temperature controlled piezoelectric oscillator according to claim 7 or 8, wherein the temperature controlled piezoelectric oscillator is heated to a predetermined temperature. A method for manufacturing a piezoelectric device according to any one of claims 1 to 6,
Forming at least two heat generating electrodes on a base substrate base material;
Forming a heating element between the heating electrodes;
Forming a desired electrode pattern on the base substrate base material;
Adjusting the frequency by thinning the thickness of the electrode pattern;
And a step of dividing the base substrate base material into a plurality of piezoelectric devices.

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