JP2007259414A - Method for fabricating elastic surface wave equipment, method for ajusting its temperature characteristics, and elastic surface wave equipment manufactured thereby - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for adjusting temperature characteristics in elastic surface wave equipment, a method for fabricating elastic surface wave equipment and the elastic surface wave equipment fabricated thereby. <P>SOLUTION: This temperature characteristic adjustment method provides for elastic surface wave equipment which comprises a single-type IDT electrode with many electrode fingers for exciting a Rayleigh elastic surface wave on a crystal substrate whose euler angle meets the requirements of (0°, 113°≤θ≤135°, 40°≤¾ψ¾≤49°) and a reflector at both sides of the IDT electrode and excites the lower limit mode of a stop band in the elastic surface wave. This method adjusts the top temperature of temperature characteristics of the elastic surface wave equipment for temperature characteristic adjustment by changing the IDT electrode logarithm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for adjusting a temperature characteristic of a surface acoustic wave device, a method for manufacturing a surface acoustic wave device, and a surface acoustic wave device having a single-type IDT electrode for exciting a Rayleigh type surface acoustic wave on a quartz substrate.

  A surface acoustic wave device using a quartz substrate typified by ST cut is improved in accuracy by utilizing the high temperature stability of quartz, and is used for an oscillator. In recent years, with the widespread use of portable communication devices and the like, high-accuracy surface acoustic wave devices that are compatible with higher frequencies and smaller sizes and that are stable with respect to temperature have been required.

As shown in Non-Patent Document 1, the surface acoustic wave device using this ST-cut quartz substrate is known to change temperature characteristics (frequency fluctuation characteristics with respect to temperature changes) depending on the thickness of the IDT electrode.
In addition, as disclosed in Patent Document 1 and Non-Patent Document 2, the surface acoustic wave device using the in-plane rotated ST-cut quartz substrate has a crystal substrate cut angle, IDT electrode thickness, standardized electrode width (IDT electrode width / It is also known that temperature characteristics change in response to changes in IDT electrode pitch. In consideration of these design factors, the surface acoustic wave device is designed so that the temperature characteristic becomes a desired characteristic.

JP 2003-152487 A IEICE Technical Report, The Institute of Electronics, Information and Communication Engineers, US99-20 (1999-06), p. 37-42 “Temperature Stability of Surface Acoustic Wave Resonators on In-Plane Rotated 33 ° Y-Cut Quartz”, JJAP, Vol. 42 (2003) pp. 3136-3138

However, the cut angle, IDT electrode thickness, standardized electrode width, etc. of the quartz substrate are set in the design of the surface acoustic wave device, and it is difficult to greatly change these design elements after forming the IDT electrode. The temperature characteristics were hardly adjusted.
Thus, there are few knowledge which can adjust the temperature characteristic of a surface acoustic wave apparatus in both a design and the manufacturing process after forming an IDT electrode.
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and its purpose is to adjust the temperature characteristics of a surface acoustic wave device that enables adjustment of temperature characteristics in both the design and the manufacturing process after forming the IDT electrode. A method, a method for manufacturing a surface acoustic wave device, and a surface acoustic wave device.

  In order to solve the above-described problems, the present invention provides a large number of Rayleigh type surface acoustic waves excited on a quartz substrate having Euler angles (0 °, 113 ° ≦ θ ≦ 135 °, 40 ° ≦ | ψ | ≦ 49 °). A temperature characteristic adjusting method for a surface acoustic wave device that includes a single type IDT electrode provided with electrode fingers and a reflector on both sides of the IDT electrode and excites a lower limit mode of a stop band of the surface acoustic wave, The apex temperature of the temperature characteristic in the surface acoustic wave device is adjusted by changing the logarithm of the IDT electrode.

  According to the temperature characteristic adjusting method of the surface acoustic wave device, in the surface acoustic wave device using the in-plane rotating ST-cut quartz substrate and exciting a lower limit mode of the surface acoustic wave stop band, which includes a single type IDT electrode. The apex temperature of the temperature characteristic can be adjusted by changing the logarithm of the IDT electrode, which has not been conventionally known, and the temperature characteristic of the surface acoustic wave device can be adjusted. Further, with this cut angle of the quartz substrate, the amount of frequency fluctuation with respect to temperature can be reduced as compared with the case where an ST cut quartz substrate is used, and a surface acoustic wave device having excellent temperature characteristics can be provided.

  In the present invention, the surface acoustic wave device further includes a comb electrode between the IDT electrode and the reflector, and the IDT electrode is cut to reduce the logarithm of the IDT electrode, or the IDT electrode has the comb shape. It is desirable to change the number of IDT electrodes by connecting the electrodes to increase the number of IDT electrodes.

  According to the temperature characteristic adjusting method of the surface acoustic wave device, the IDT electrode is logarithmized by connecting the comb electrode to the IDT electrode or cutting the IDT electrode in the manufacturing process after forming the IDT electrode. It can be increased or decreased. And the vertex temperature of a temperature characteristic can be adjusted and the temperature characteristic of a surface acoustic wave apparatus can be adjusted. Accordingly, variations in temperature characteristics in the manufacturing process can be suppressed, and a more stable surface acoustic wave device can be obtained.

  In the present invention, it is preferable that the IDT electrode is cut by irradiating a part of the IDT electrode with a laser beam to reduce the number of electrode fingers of the IDT electrode.

  According to the temperature characteristic adjusting method of the surface acoustic wave device, the IDT electrode can be easily cut by irradiating the IDT electrode with laser light, and the number of electrode fingers of the IDT electrode can be reduced.

  In the present invention, it is desirable to connect the IDT electrode and the comb electrode by applying a conductive material by an ink jet method.

  According to the temperature characteristic adjusting method of the surface acoustic wave device, the IDT electrode and the comb electrode can be easily connected by applying a conductive material between the IDT electrode and the comb electrode by an ink jet method.

  In the present invention, a single type in which a large number of electrode fingers for exciting Rayleigh surface acoustic waves are provided on a quartz substrate having Euler angles (0 °, 0 ° ≦ θ ≦ 180 °, 9 ° ≦ | ψ | ≦ 46 °). A temperature characteristic adjusting method for a surface acoustic wave device including a reflector on both sides of the IDT electrode and exciting an upper limit mode of the stopband of the surface acoustic wave, wherein the logarithm of the IDT electrode is changed. The first-order temperature coefficient of the temperature characteristic of the cubic function in the surface acoustic wave device is adjusted.

  According to this method for adjusting the temperature characteristics of a surface acoustic wave device, in a surface acoustic wave device using an in-plane rotating ST-cut quartz substrate and having a single type IDT electrode to excite an upper limit mode of a surface acoustic wave stop band. By changing the logarithm of the IDT electrode, which has not been known so far, the first-order temperature coefficient of the temperature characteristic of the cubic function in the surface acoustic wave device can be adjusted, and the temperature characteristic of the surface acoustic wave device can be adjusted Is possible. Then, with this cut angle of the quartz substrate, the amount of frequency fluctuation with respect to temperature can be reduced compared to the case where an ST cut quartz substrate is used, and a surface acoustic wave device having excellent temperature characteristics can be provided.

  In the present invention, a single type in which a number of electrode fingers for exciting a Rayleigh type surface acoustic wave are provided on a quartz substrate having Euler angles (0 °, 95 ° ≦ θ ≦ 155 °, 33 ° ≦ | ψ | ≦ 46 °). A temperature characteristic adjusting method for a surface acoustic wave device including a reflector on both sides of the IDT electrode and exciting an upper limit mode of the stopband of the surface acoustic wave, wherein the logarithm of the IDT electrode is changed. It is desirable to adjust the first-order temperature coefficient of the temperature characteristic of the cubic function in the surface acoustic wave device.

  According to this method for adjusting the temperature characteristics of a surface acoustic wave device, in a surface acoustic wave device using an in-plane rotating ST-cut quartz substrate and having a single type IDT electrode to excite an upper limit mode of a surface acoustic wave stop band. By changing the logarithm of the IDT electrode, which has not been known so far, the first-order temperature coefficient of the temperature characteristic of the cubic function in the surface acoustic wave device can be adjusted, and the temperature characteristic of the surface acoustic wave device can be adjusted Is possible. Also, with this crystal substrate cut angle, the amount of frequency fluctuation with respect to temperature can be reduced compared with the case where the lower limit mode of the stop band is used using the in-plane rotated ST cut crystal substrate, and the temperature is high. A surface acoustic wave device having characteristics can be provided.

  In the present invention, the surface acoustic wave device further includes a comb electrode between the IDT electrode and the reflector, and the IDT electrode is cut to reduce the logarithm of the IDT electrode, or the IDT electrode has the comb electrode. It is desirable to change the number of IDT electrodes by connecting the IDT and increasing the number of IDT electrodes.

  According to the temperature characteristic adjusting method of the surface acoustic wave device, the logarithm of the IDT electrode can be obtained by connecting the comb electrode to the IDT electrode or cutting the IDT electrode in the manufacturing process after forming the IDT electrode. Can be increased or decreased. And the primary temperature coefficient of the temperature characteristic of the cubic function in a surface acoustic wave apparatus can be adjusted, and the temperature characteristic of a surface acoustic wave apparatus can be adjusted. Accordingly, variations in temperature characteristics in the manufacturing process can be suppressed, and a more stable surface acoustic wave device can be obtained.

  In the present invention, it is preferable that the IDT electrode is cut by irradiating a part of the IDT electrode with a laser beam to reduce the number of IDT electrodes.

  According to the temperature characteristic adjusting method of the surface acoustic wave device, the IDT electrode can be easily cut by irradiating the IDT electrode with laser light, and the number of electrode fingers of the IDT electrode can be reduced.

  In the present invention, it is desirable to connect the IDT electrode and the comb electrode by applying a conductive material by an ink jet method.

  According to the temperature characteristic adjusting method of the surface acoustic wave device, the IDT electrode and the comb electrode can be easily connected by applying a conductive material between the IDT electrode and the comb electrode by an ink jet method.

  The surface acoustic wave device of the present invention is manufactured by the method for adjusting temperature characteristics of the surface acoustic wave device.

  According to this surface acoustic wave device, the temperature characteristics of the surface acoustic wave device are adjusted by changing the logarithm of the IDT electrode, and a surface acoustic wave device having excellent temperature characteristics can be provided.

  In the present invention, a single-type IDT electrode for exciting a Rayleigh type surface acoustic wave on a quartz substrate, a plurality of comb-shaped electrodes formed on both sides of the IDT electrode independently of the IDT electrodes, and an outer side of the comb-shaped electrode The IDT electrode and at least one of the comb electrodes are preferably connected with a conductive material.

  According to this surface acoustic wave device, an IDT electrode and a comb-shaped electrode are connected by a conductive material, the logarithm of the IDT electrode is increased, temperature characteristics are adjusted, and a surface acoustic wave device having excellent temperature characteristics is obtained. Can do.

  In the present invention, a single-type IDT electrode for exciting a Rayleigh type surface acoustic wave on a quartz substrate, a plurality of comb-shaped electrodes formed on both sides of the IDT electrode independently of the IDT electrodes, and an outer side of the comb-shaped electrode Preferably, the reflector is formed, and the reflector and at least one of the comb electrodes are connected by a conductive material.

  According to this surface acoustic wave device, the logarithm of the IDT electrode is increased or decreased by connecting the IDT electrode and the comb electrode or by cutting the IDT electrode, the temperature characteristics are adjusted, and the comb electrode is connected to the reflector. By doing so, it is possible to increase the reflection coefficient of the surface acoustic wave of the reflector, and it is possible to provide a surface acoustic wave device having excellent temperature characteristics and excellent characteristics.

  The present invention is a single type in which a large number of electrode fingers for exciting a Rayleigh type surface acoustic wave are provided on a quartz substrate having Euler angles (0 °, 113 ° ≦ θ ≦ 135 °, 40 ° ≦ | ψ | ≦ 49 °). And a reflector disposed on both sides of the IDT electrode, and a method of manufacturing a surface acoustic wave device that excites a lower limit mode of a stop band of the surface acoustic wave, the IDT electrode The temperature characteristic adjustment process of adjusting the vertex temperature of the temperature characteristic in the said surface acoustic wave apparatus by changing the logarithm of this is characterized.

  According to this method for manufacturing a surface acoustic wave device, in a surface acoustic wave device for exciting a lower limit mode of a stop surface wave of a surface acoustic wave using an in-plane rotating ST-cut quartz substrate and having a single IDT electrode, By changing the logarithm of the IDT electrode, which has not been known, the apex temperature of the temperature characteristic can be adjusted, and the temperature characteristic of the surface acoustic wave device can be adjusted. In addition, with this crystal substrate cut angle, the amount of frequency fluctuation with respect to temperature can be reduced compared to the case of using an ST cut crystal substrate, and a method of manufacturing a surface acoustic wave device having excellent temperature characteristics is provided. it can.

  In the present invention, the surface acoustic wave device includes a comb electrode between the IDT electrode and the reflector, and the temperature characteristic adjusting step cuts the IDT electrode to reduce the logarithm of the IDT electrode. Alternatively, it is preferable that the comb-shaped electrode is connected to the IDT electrode to increase the number of IDT electrodes to change the number of IDT electrodes.

  According to this method for manufacturing a surface acoustic wave device, the number of logarithms of an IDT electrode is increased or decreased by connecting a comb electrode to the IDT electrode or cutting the IDT electrode in the manufacturing process after forming the IDT electrode. be able to. And the vertex temperature of a temperature characteristic can be adjusted and the temperature characteristic of a surface acoustic wave apparatus can be adjusted. Thus, variations in temperature characteristics in the manufacturing process can be suppressed, and a more stable surface acoustic wave device manufacturing method can be provided.

  In the present invention, it is desirable that the temperature characteristic adjusting step is a step of reducing the number of electrode fingers of the IDT electrode by cutting the IDT electrode by irradiating a part of the IDT electrode with laser light.

  According to this surface acoustic wave device manufacturing method, the IDT electrode can be easily cut by irradiating the IDT electrode with laser light, and the number of electrode fingers of the IDT electrode can be reduced.

  In the present invention, the temperature characteristic adjusting step is preferably a step of connecting the IDT electrode and the comb electrode by applying a conductive material by an ink jet method.

  According to this method for manufacturing a surface acoustic wave device, an IDT electrode and a comb-shaped electrode can be easily connected by applying a conductive material between the IDT electrode and the comb-shaped electrode by an inkjet method.

  In the present invention, a number of electrode fingers for exciting Rayleigh surface acoustic waves are provided on a quartz substrate having Euler angles (0 °, 0 ° ≦ θ ≦ 180 °, 9 ° ≦ | ψ | ≦ 46 °). A method of manufacturing a surface acoustic wave device that includes a step of forming a single type IDT electrode and reflectors disposed on both sides of the IDT electrode, and excites an upper limit mode of a stop band of the surface acoustic wave, It includes a temperature characteristic adjustment step of adjusting the first-order temperature coefficient of the temperature characteristic of the cubic function in the surface acoustic wave device by changing the logarithm of the IDT electrode.

  According to this method for manufacturing a surface acoustic wave device, in a surface acoustic wave device that uses an in-plane rotating ST-cut quartz substrate and is provided with a single type IDT electrode and excites an upper limit mode of a surface acoustic wave stopband, By changing the logarithm of the IDT electrode, which is not known, it is possible to adjust the first-order temperature coefficient of the temperature characteristic of the cubic function in the surface acoustic wave device, and to adjust the temperature characteristic of the surface acoustic wave device. It is. The cut angle of the quartz substrate can provide a method of manufacturing a surface acoustic wave device that can reduce the amount of frequency fluctuation with respect to temperature and has excellent temperature characteristics as compared with the case where an ST cut quartz substrate is used. it can.

  In the present invention, a single type in which a number of electrode fingers for exciting a Rayleigh type surface acoustic wave are provided on a quartz substrate having Euler angles (0 °, 95 ° ≦ θ ≦ 155 °, 33 ° ≦ | ψ | ≦ 46 °). And a reflector disposed on both sides of the IDT electrode, the method of manufacturing the surface acoustic wave device for exciting the upper limit mode of the stopband of the surface acoustic wave, the IDT electrode It is desirable to include a temperature characteristic adjusting step of adjusting the first-order temperature coefficient of the temperature characteristic of the cubic function in the surface acoustic wave device by changing the logarithm of the surface acoustic wave device.

  According to this method for manufacturing a surface acoustic wave device, in a surface acoustic wave device that uses an in-plane rotating ST-cut quartz substrate and is provided with a single type IDT electrode and excites an upper limit mode of a surface acoustic wave stopband, By changing the logarithm of the IDT electrode, which is not known, it is possible to adjust the first-order temperature coefficient of the temperature characteristic of the cubic function in the surface acoustic wave device, and to adjust the temperature characteristic of the surface acoustic wave device. It is. Also, with this crystal substrate cut angle, the amount of frequency fluctuation with respect to temperature can be reduced compared with the case where the lower limit mode of the stop band is used using the in-plane rotated ST cut crystal substrate, and the temperature is high. A method of manufacturing a surface acoustic wave device having characteristics can be provided.

  In the present invention, the surface acoustic wave device has a comb electrode between the IDT electrode and the reflector, and the temperature characteristic adjusting step cuts the IDT electrode to reduce the logarithm of the IDT electrode, or It is preferable that the step of changing the number of IDT electrodes by connecting the IDT electrodes to the comb electrodes and increasing the number of IDT electrodes.

  According to this method for manufacturing a surface acoustic wave device, the number of logarithms of an IDT electrode is increased or decreased by connecting the comb electrode to the IDT electrode or cutting the IDT electrode in the manufacturing process after forming the IDT electrode. can do. And the primary temperature coefficient of the temperature characteristic of the cubic function in a surface acoustic wave apparatus can be adjusted, and the temperature characteristic of a surface acoustic wave apparatus can be adjusted. Thus, variations in temperature characteristics in the manufacturing process can be suppressed, and a more stable surface acoustic wave device manufacturing method can be provided.

  In the present invention, it is desirable that the temperature characteristic adjusting step is a step of cutting the IDT electrode by irradiating a part of the IDT electrode with a laser beam to reduce the logarithm of the IDT electrode.

  According to this surface acoustic wave device manufacturing method, the IDT electrode can be easily cut by irradiating the IDT electrode with laser light, and the number of electrode fingers of the IDT electrode can be reduced.

  In the present invention, the temperature characteristic adjusting step is preferably a step of connecting the IDT electrode and the comb electrode by applying a conductive material by an ink jet method.

  According to this method for manufacturing a surface acoustic wave device, an IDT electrode and a comb-shaped electrode can be easily connected by applying a conductive material between the IDT electrode and the comb-shaped electrode by an inkjet method.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings.
(First embodiment)

Prior to the description of the embodiment of the present invention, Euler angles (φ, θ, ψ) display will be described in order to specify the cut-out angle (cut angle) of the quartz substrate and the propagation direction of the surface acoustic wave.
FIG. 1 is a diagram for explaining the Euler angles.
The crystal axis of quartz is defined by the X axis (electrical axis), the Y axis (mechanical axis), and the Z axis (optical axis), and the Euler angles (0 °, 0 °, 0 °) are Become. In the present invention, the angle φ for rotating the X axis and the Y axis with the Z axis as the rotation axis is fixed as φ = 0 °.

When the Y axis and the Z axis are rotated counterclockwise by the angle θ with the X axis as the rotation axis, the newly generated coordinate axes are defined as the Y ′ axis and the Z ′ axis, respectively. The crystal substrate 1 is cut by a plane orientation including the X axis and the Y ′ axis with the Z ′ axis as a normal line. Then, in the quartz substrate 1 cut in this plane orientation, when the X axis and the Y ′ axis are rotated by an angle ψ with the Z ′ axis as the rotation axis, the newly generated coordinate axes are the X ′ axis and the Y ″ axis, respectively. This X′-axis is the surface acoustic wave propagation direction of the surface acoustic wave device 2. The angle ψ in the quartz substrate 1 is called an in-plane rotation angle, and when there is no in-plane rotation, ψ = 0 °. is there.
Thus, the cut-out angle of the quartz substrate and the surface acoustic wave propagation direction can be displayed and specified by the Euler angles (φ, θ, ψ).

Next, the temperature characteristic adjusting method of the surface acoustic wave device according to the present invention and the background to the surface acoustic wave device will be described.
FIG. 2 is an explanatory view illustrating the configuration of the surface acoustic wave device. FIG. 2A is a schematic plan view of the surface acoustic wave device, and FIG. 2B is a schematic cross-sectional view taken along the line AA in FIG.

The surface acoustic wave device 10 includes an IDT electrode 20 on the surface of a quartz substrate 11. The IDT electrode 20 is composed of an electrode 12 provided with a large number of electrode fingers 21 and an electrode 13 provided with a large number of electrode fingers 22, and the electrode fingers 21 and 22 are arranged so as to mesh with each other. The electrode fingers 21 and 22 are formed with a thickness H and an electrode width d, and an interval (pitch) P between the electrode fingers 21 and the electrode fingers 22 is continuously formed at equal intervals. Also, one electrode finger 21 and 22 is provided for each wavelength λ of the surface acoustic wave. In general, the IDT electrode 20 having this configuration is called a single-type IDT electrode. Also, one electrode finger 21 and one electrode finger 22 are called a pair of IDT electrodes, and the number of the pair of IDT electrodes is expressed as a logarithm of the whole IDT electrode. The electrodes 12 and 13 are driven so as to be in opposite phases to each other.
The quartz substrate 11 is cut from the quartz crystal so as to have a certain cut angle, and the direction of the arrow E is configured to match the X ′ axis that is the propagation direction of the surface acoustic wave described in FIG.

  In Rayleigh type surface acoustic wave excited by an IDT electrode provided on a piezoelectric substrate such as quartz, it is known that two frequency solutions called stop bands can be obtained by calculation, and these two frequency solutions are low frequencies. Either (lower limit mode) or higher frequency (upper limit mode) is used for excitation. As described above, when a single-type IDT electrode provided with two electrode fingers in one wavelength of a surface acoustic wave is provided on an ST cut quartz substrate, the surface acoustic wave may be excited in the lower limit mode of the stop band. know.

Here, the inventor paid attention to the logarithm of the IDT electrode, and analyzed the change in the temperature characteristics of the surface acoustic wave device when the logarithm of the IDT electrode was changed.
First, the change in the logarithm of the IDT electrode and the temperature characteristic when the ST cut quartz substrate was used was analyzed.
FIG. 3 is a graph showing temperature characteristics when an ST cut quartz substrate is used and the logarithm of the IDT electrode is changed.

Specifically, in FIG. 3, a single-type IDT electrode is formed using a Euler angle display (0 °, 123 °, 0 °) substrate as an ST cut quartz substrate, and the thickness H of the electrode finger is divided by the wavelength λ. Standardized electrode thickness H / λ = 0.03, electrode finger width d divided by electrode finger pitch P, standardized electrode width η (d / P) = 0.5, intersecting width of electrode fingers intersecting = 32λ When (λ = 10 μm), the temperature characteristics of 90 pairs and 265 pairs of IDT electrodes are shown. In the graph of FIG. 3, the vertical axis represents the frequency deviation based on the frequency at 20 ° C., and the horizontal axis represents the temperature.
According to FIG. 3, there is no change in temperature characteristics between 90 and 265 pairs of IDT electrodes, and when an ST-cut quartz substrate is used, the number of IDT electrodes does not affect the temperature characteristics.

  Next, the change in the logarithm of the IDT electrode and the temperature characteristic when the in-plane rotation ST cut quartz substrate was used was analyzed. The in-plane rotation ST-cut quartz substrate uses a cut angle of Euler angle display (0 °, 113 ° ≦ θ ≦ 135 °, 40 ° ≦ | ψ | ≦ 49 °) as disclosed in Patent Document 1. In the surface acoustic wave device using this in-plane rotated ST-cut quartz substrate, the lower limit mode of the stop band is used as described in Non-Patent Document 2.

FIG. 4 is a graph showing temperature characteristics when an in-plane rotated ST-cut quartz substrate is used and the logarithm of the IDT electrode is changed.
Specifically, in FIG. 4, a single-type IDT electrode is formed using a Euler angle display (0 °, 123 °, 43 °) substrate as an in-plane rotated ST-cut quartz substrate, and the thickness H of the electrode finger is set to a wavelength λ. The normalized electrode thickness H / λ = 0.04 divided by λ, the electrode finger width d divided by the electrode finger pitch P, and the normalized electrode width η (d / P) = 0.5, the intersection of the electrode fingers intersecting When width = 32λ (λ = 10 μm), the temperature characteristics of IDT electrodes are 70, 90, 150, and 265 pairs. In the graph of FIG. 4, the frequency deviation based on the frequency at 20 ° C. is plotted on the vertical axis, and the temperature is plotted on the horizontal axis.

According to FIG. 4, the logarithm of each IDT electrode shows a temperature characteristic curve of a quadratic function, and has a peak temperature at which the frequency (frequency deviation) is maximum at a certain temperature. It can also be seen that the peak temperature moves to a lower temperature as the number of IDT electrode pairs increases.
For example, when the number of IDT electrode pairs is 90, the vertex temperature is about 50 ° C., and when the number of IDT electrode pairs is 265, the vertex temperature is about 15 ° C. At this time, if the operating temperature range of the surface acoustic wave device is −40 ° C. to 90 ° C., the frequency variation amount is about 110 ppm when the number of IDT electrodes is 90 pairs and about 75 ppm when the number of IDT electrodes is 265 pairs. can get.

As described above, the temperature characteristics can be adjusted by adjusting the apex temperature by changing the logarithm of the IDT electrode. In a surface acoustic wave device using this in-plane rotating ST-cut quartz substrate and using a lower limit mode of a stop surface wave of a surface acoustic wave provided with a single type IDT electrode, the temperature characteristics change according to the logarithm of the IDT electrode. It was not known.
By utilizing this fact, the temperature characteristics of the surface acoustic wave device can be adjusted by considering the logarithm of the IDT electrode in the design of the surface acoustic wave device.
Further, the secondary temperature coefficient of the ST cut quartz substrate is generally −3.4 × 10 ⁻⁸ (1 / ° C. ² ), and when the temperature range is −40 ° C. to 90 ° C., the frequency fluctuation amount is about 144 ppm. is there. On the other hand, the secondary temperature coefficient of the lower limit mode of the stop band using the in-plane rotating ST cut quartz substrate is −1.4 × 10 ⁻⁸ (1 / ° C. ² ), and the temperature range is −40 ° C. to 90 ° C. In the case of ° C., the frequency fluctuation amount is about 59 ppm.
Thus, at the cut angle (0 °, 113 ° ≦ θ ≦ 135 °, 40 ° ≦ | ψ | ≦ 49 °) of the quartz crystal substrate according to the present invention, the temperature is higher than when the ST-cut quartz crystal substrate is used. Therefore, it is possible to provide a surface acoustic wave device having excellent temperature characteristics.

Next, a description will be given of a method for adjusting the temperature characteristics in the manufacturing process after forming the IDT electrodes by utilizing the fact that the temperature characteristics change depending on the logarithm of the IDT electrodes described above.
5A and 5B are schematic views showing the configuration of the surface acoustic wave device according to the present embodiment. FIG. 5A is a schematic plan view, and FIG. 5B is a schematic view taken along the line AA in FIG. It is sectional drawing.

  The surface acoustic wave device 30 includes an IDT electrode 32 on the surface of a quartz substrate 31, comb electrodes 35, 36, 37, and 38 on both sides thereof, and reflectors 33 and 34 on the outside thereof. The IDT electrode 32 is arranged so that the electrode fingers 32b and 32d are engaged with each other. The electrode finger 32b is connected to the bus bar 32a, and the electrode finger 32d is connected to the bus bar 32c. The electrode fingers 32b and 32d are formed with a thickness H and an electrode width d, and an interval (pitch) P between the electrode fingers 32b and the electrode fingers 32d is continuously formed at equal intervals. Further, one electrode finger 32b, 32d is provided in one wavelength λ of the surface acoustic wave, thereby forming a single type IDT electrode 32.

On one side of the IDT electrode 32, comb-shaped electrodes 35 and 36 independent of the IDT electrode 32 are formed. The comb-shaped electrode 35 includes electrode fingers 35b and 35d and is connected to bus bars 35a and 35c, respectively. Similarly, the comb-shaped electrode 36 includes electrode fingers 36b and 36d and is connected to bus bars 36a and 36c, respectively.
On the other side of the IDT electrode 32, comb-shaped electrodes 37 and 38 that are independent of the IDT electrode 32 are formed. The comb-shaped electrode 37 includes electrode fingers 37b and 37d and is connected to bus bars 37a and 37c, respectively. Similarly, the comb-shaped electrode 38 includes electrode fingers 38b and 38d and is connected to bus bars 38a and 38c, respectively.

The electrode fingers 35b, 35d, 36b, 36d, 37b, 37d, 38b, and 38d are arranged so that the comb electrodes 35, 36, 37, and 38 have the same pitch continuously from the electrode fingers 32b and 32d of the IDT electrode 32. Has been.
In this embodiment, the comb-shaped electrodes 35, 36, 37, and 38 having a pair of electrode fingers are formed. However, for example, a comb-shaped electrode having five pairs of electrode fingers may be used, and the logarithm thereof may be changed as appropriate. You may do it.

Further, reflectors 33 and 34 are formed so as to sandwich the IDT electrode 32 and the comb-shaped electrodes 35, 36, 37 and 38 from both sides.
The quartz substrate 31 is cut out of the quartz so as to have a cut angle of Euler angle display (0 °, 113 ° ≦ θ ≦ 135 °, 40 ° ≦ | ψ | ≦ 49 °), and the direction of the arrow E is illustrated. 1 is configured to match the X ′ axis, which is the propagation direction of the surface acoustic wave described in 1.

Next, a procedure for adjusting temperature characteristics using the surface acoustic wave device 30 will be described.
FIG. 6 is a flowchart for explaining the procedure of the temperature characteristic adjusting method in the surface acoustic wave device. 7 and 8 are schematic plan views for explaining the temperature characteristic adjusting method. Here, the temperature characteristic adjusting method will be described with reference to FIGS. 7 and 8 according to the flowchart of FIG.

  First, in step S1, the temperature characteristics of the surface acoustic wave device 30 described with reference to FIG. 5 are measured. Next, in step S2, it is confirmed whether or not the peak temperature of the temperature characteristic is within a desired range based on the measured temperature characteristic. When the peak temperature of the temperature characteristic is not within the desired range, the process proceeds to step S3, and it is determined whether or not the peak temperature of the measured temperature characteristic is higher than the desired range. If the vertex temperature is lower than the desired range, the process proceeds to step S4, and the work for cutting the IDT electrode 32 is started.

Here, as shown in FIG. 7A, the IDT electrode 32 is cut from the both sides of the IDT electrode 32 along the cutting lines BB and CC along a desired logarithmic IDT electrode. In cutting the IDT electrode 32, the laser bars are irradiated to the bus bars 32a and 32c of the IDT electrode 32 to cut the bus bars 32a and 32c. By this cutting, the comb-shaped electrodes 41 and 42 having the electrode fingers connected to the bus bars 41a, 41c, 42a, and 42c are separated from the IDT electrode 32.
In order to maintain left-right symmetry about the IDT electrode 32 of the surface acoustic wave device 30, it is preferable to separate the same logarithm from both sides of the IDT electrode 32.

  Next, returning to step S1, the temperature characteristic is measured again. Steps S1, S2, S3, and S4 are repeated until the vertex temperature falls within the desired range. When the vertex temperature falls within the desired range at step S2, the temperature characteristic adjustment of the surface acoustic wave device is completed, and the process returns to step S6. The operation proceeds to connect the independent comb electrodes to the reflectors 33 and 34.

As shown in FIG. 7B, the operation of connecting the comb electrodes to the reflectors 33 and 34 is performed by first adding a solution containing conductive particles between the reflector 33 and the bus bars 36a and 36c of the comb electrode 36 by an ink jet method. A droplet 45 made of is applied. Subsequently, a droplet 45 is applied between the bus bars 36a and 36c of the comb electrode 36 and the bus bars 35a and 35c of the comb electrode 35 by an ink jet method. Then, a droplet 45 is applied between the bus bars 35a and 35c of the comb electrode 35 and the bus bars 41a and 41c of the comb electrode 41 by an ink jet method.
Similarly, in the connection between the reflector 34 and the comb-shaped electrodes 38, 37, and 42, the droplet 45 is applied between the respective bus bars by the ink jet method.
After applying the droplet 45, the droplet 45 is dried, whereby the reflector 33 and the comb electrodes 36, 35, and 41 and the reflector 34 and the comb electrodes 38, 37, and 42 are connected. Complete.

In step S3 of FIG. 6, if the vertex temperature is higher than the desired range, the process proceeds to step S5, and the operation of connecting the comb electrode to the IDT electrode 32 is started.
The operation of connecting the comb electrodes is an operation of connecting the comb electrodes corresponding to the desired logarithm of the IDT electrodes to the IDT electrodes 32. As shown in FIG. 8A, first, a droplet 45 made of a solution containing conductive particles is applied between the bus bars 32a and 32c of the IDT electrode 32 and the bus bars 35a and 35c of the comb electrode 35 by an ink jet method. Next, a droplet 45 is applied between the bus bars 32 a and 32 c of the IDT electrode 32 and the bus bars 37 a and 37 c of the comb electrode 37 by an ink jet method. Thereafter, the droplet 45 is dried, whereby the IDT electrode 32 and the comb-shaped electrodes 35 and 37 are connected, and electrical conduction is made.
In order to maintain left-right symmetry about the IDT electrode 32 of the surface acoustic wave device 30, it is preferable to connect comb-shaped electrodes having the same logarithm from both sides of the IDT electrode 32.

Next, returning to step S1, the temperature characteristic is measured again. Steps S1, S2, S3, and S5 are repeated until the vertex temperature falls within the desired range. When the vertex temperature falls within the desired range at step S2, the temperature characteristic adjustment of the surface acoustic wave device is finished, and the process goes to step S6. The operation proceeds to connect the independent comb electrodes to the reflectors 33 and 34.
As shown in FIG. 8B, the operation of connecting the comb electrodes to the reflectors 33 and 34 is as follows. First, a solution containing conductive particles between the reflector 33 and the bus bars 36a and 36c of the comb electrode 36 by an ink jet method. A droplet 45 made of is applied. Next, similarly, a droplet 45 is applied between the reflector 34 and the bus bars 38a, 38c of the comb-shaped electrode 38 by an ink jet method. Thereafter, by drying the droplet 45, the reflector 33 and the comb electrode 36 and the reflector 34 and the comb electrode 38 are connected, and the surface acoustic wave device 30 is completed.

  As described above, in this embodiment, in the manufacturing process after forming the IDT electrode 32, the IDT electrode 32 is cut to reduce the logarithm of the IDT electrode 32, so that the peak temperature of the temperature characteristic is increased to the high temperature side. Further, by connecting a comb electrode to the IDT electrode 32, the peak temperature of the temperature characteristic can be adjusted to the low temperature side. Thus, the surface acoustic wave device 30 that uses the in-plane rotation ST-cut quartz substrate 31 and includes the single type IDT electrode 32 and excites the lower limit mode of the stop band of the surface acoustic wave has not been conventionally known. The apex temperature of the temperature characteristic can be adjusted by changing the logarithm of the IDT electrode 32, and the temperature characteristic of the surface acoustic wave device 30 can be adjusted. Accordingly, variations in temperature characteristics in the manufacturing process can be suppressed, and a more stable surface acoustic wave device 30 can be obtained.

Further, by irradiating the IDT electrode 32 with laser light, the IDT electrode 32 can be easily cut, and the number of electrode fingers of the IDT electrode 32 can be reduced. Furthermore, the IDT electrode 32 and the comb electrode can be easily connected by applying a conductive material between the IDT electrode 32 and the comb electrode by an ink jet method.
Then, by connecting the comb electrodes to the reflectors 33 and 34, the comb electrodes can be used as a reflector, so that the reflection coefficient of the reflector can be increased, and the surface acoustic wave device 30 having good characteristics can be obtained. Can do.
(Second Embodiment)

Next, an embodiment of a surface acoustic wave device using an in-plane rotating ST-cut quartz substrate and using an upper limit mode of a surface acoustic wave stop band provided with a single IDT electrode will be described.
Conventionally known ST-cut quartz substrates have Euler angles, for example (0 °, 123 °, 0 °). When a single-type IDT electrode is formed using this substrate, surface acoustic waves are excited. This is the lower limit mode in the stop band.
In the single type IDT electrode, whether the upper limit mode and the lower limit mode of the surface acoustic wave stop band are excited is determined by the frequency difference between the short-circuit condition and the open condition in the frequency of each mode. The mode is known to be excited.

Table 1 is a table showing the difference in frequency between the short-circuit condition in the upper limit mode and the open condition in the ST-cut quartz crystal substrate using the single type IDT electrode and the quartz substrate having the cut angle according to the present invention.
In Table 1, the surface acoustic wave wavelength λ = 10 μm, the electrode electrode width d divided by the electrode finger pitch P, and the electrode electrode thickness η (d / P), and the electrode finger thickness H are the wavelength λ. The conditions of the normalized electrode thickness H / λ divided by are changed. The frequency of the short-circuit condition in the upper limit mode is fus, the frequency of the open condition in the upper limit mode is fuo, and the difference is indicated by an absolute value.

In Table 1, Condition A is the case where an ST-cut quartz substrate is used and η = 0.5 and H / λ = 0.03, and the difference between the short-circuit condition frequency and the open-circuit condition frequency in the upper limit mode is zero. ing. Condition B is a case where an ST-cut quartz substrate is used and η = 0.7 and H / λ = 0.10, and the difference between the frequency of the short-circuit condition and the frequency of the open condition in the upper limit mode is zero. .
Thus, it can be seen that when the ST cut quartz substrate is used, the surface acoustic wave cannot be excited in the upper limit mode of the stop band even if the dimension of the electrode finger in the IDT electrode changes.

Next, a quartz substrate having Euler angles (0 °, 123 °, 41 °), which are cut angles used in the present invention, will be described as an example.
Condition C is a case where a quartz substrate having a cut angle according to the present invention is used and η = 0.5 and H / λ = 0.03. The difference between the frequency of the short-circuit condition and the frequency of the open condition in the upper limit mode is 0. It is 0015 MHz.
Similarly, the condition D is a case where the crystal substrate having the cut angle according to the present invention is used and η = 0.7 and H / λ = 0.10, and the frequency of the short-circuit condition in the upper limit mode and the frequency of the open condition are The difference is 0.1667 MHz.
Thus, it can be seen that the surface acoustic wave can be excited in the upper limit mode of the stop band when the above-described quartz substrate is used. This is made asymmetric by shifting the cut angle with respect to the symmetry in the crystal of the crystal, and the surface acoustic wave in the upper limit mode can be excited.

Next, frequency variation with respect to temperature in the case of using the cut-angle quartz crystal substrate of the present embodiment using the upper limit mode of the stop band will be described.
FIG. 9 is a graph showing the frequency variation with respect to the temperature of the surface acoustic wave device according to the present embodiment. The frequency fluctuation amount = the maximum value of the frequency deviation−the minimum value of the frequency deviation, and the frequency deviation = (frequency at each temperature−frequency at 25 ° C.) / Frequency at 25 ° C.
As conditions, the temperature range is −40 ° C. to 90 ° C., the standardized electrode width d / P = 0.7 in the single IDT electrode, and the standardized electrode thickness H / λ = 0.10. When the cut angle of the quartz substrate is fixed to φ = 0 ° and the in-plane rotation angle ψ = 0 ° to 90 ° is changed between θ = 0 ° and 180 °, the frequency fluctuation amount is the optimum value (minimum) Value) is shown by black circles. Further, the in-plane rotation angle ψ at that time is indicated by triangles. For example, when φ = 0 ° and θ = 40 °, the minimum value of the frequency variation when ψ = 0 ° to 90 ° is changed is about 80 ppm, and the in-plane rotation angle ψ at that time is It is approximately 12 °.
It should be noted that ψ is the same because the symmetry of the quartz crystal is used, and the result is the same regardless of which of the positive and negative angles is used. In addition, a crystal substrate having a crystallographically equivalent cut angle may be used without regard to notation by Euler angles.

Thus, in the quartz substrate in which the cut angle and the surface acoustic wave propagation direction are (0 °, 0 ° ≦ θ ≦ 180 °, 9 ° ≦ | ψ | ≦ 46 °), the propagation direction of the surface acoustic wave is the quartz substrate. The crystal can be moved away from the symmetrical position of the crystal, and the upper limit mode of the stopband of the surface acoustic wave can be excited using the single type IDT electrode.
Further, in the case where the ST cut quartz substrate is used in the quartz substrate in which the cut angle and the surface acoustic wave propagation direction are (0 °, 0 ° ≦ θ ≦ 180 °, 9 ° ≦ | ψ | ≦ 46 °) from FIG. The amount of frequency fluctuation can be further reduced. Further, in a quartz substrate in which the cut angle and the surface acoustic wave propagation direction are (0 °, 95 ° ≦ θ ≦ 155 °, 33 ° ≦ | ψ | ≦ 46 °), an in-plane rotated ST-cut quartz substrate is used, and a lower limit mode is used. It can be seen that the amount of frequency fluctuation is smaller than when using.

FIG. 10 is a graph showing temperature characteristics when the logarithm of the IDT electrode of the surface acoustic wave device that excites the upper limit mode of the stop band using the in-plane rotated ST-cut quartz substrate is changed.
Specifically, in FIG. 10, a single-type IDT electrode is formed using a Euler angle display (0 °, 123 °, 41 °) substrate as an in-plane rotated ST-cut quartz substrate, and the thickness H of the electrode finger is set to a wavelength λ. The normalized electrode thickness H / λ = 0.10 divided by ## EQU10 ## The normalized electrode width η (d / P) = 0.7 obtained by dividing the electrode finger width d by the electrode finger pitch P. When width = 32λ (λ = 10 μm), the temperature characteristics of IDT electrodes are 50, 70, 90, 150, and 265 pairs. In the graph of FIG. 10, the vertical axis indicates the frequency deviation based on the frequency at 20 ° C., and the horizontal axis indicates the temperature.

  According to FIG. 10, the logarithm of each IDT electrode shows a temperature characteristic of a cubic function. When the logarithm of the IDT electrode decreases, the temperature characteristic curve appears as if it is rotated clockwise. This corresponds to a decrease in the first-order temperature coefficient when the temperature characteristic curve is developed by Taylor. For example, when the number of IDT electrode pairs is 265, the primary temperature coefficient is almost 0, whereas when the number is 90 pairs, the primary temperature coefficient has a negative value. At this time, if the operating temperature range of the surface acoustic wave device is −40 ° C. to 90 ° C., the frequency variation amount is about 67 ppm when the number of IDT electrodes is 90 pairs and about 10 ppm when the number of IDT electrodes is 265 pairs. can get.

Thus, the temperature characteristic can be adjusted by changing the logarithm of the IDT electrode to adjust the first-order temperature coefficient of the cubic function. In a surface acoustic wave device that uses this in-plane rotating ST-cut quartz substrate and uses an upper limit mode of a stop surface wave of a surface acoustic wave provided with a single type IDT electrode, the temperature characteristics change according to the logarithm of the IDT electrode. It was not known.
By utilizing this fact, the temperature characteristics of the surface acoustic wave device can be adjusted by considering the logarithm of the IDT electrode in the design of the surface acoustic wave device.
Further, the cut angle of this quartz substrate (0 °, 95 ° ≦ θ ≦ 155 °, 33 ° ≦ | ψ | ≦ 46 °) is compared with the lower limit mode of the stop band using the in-plane rotation ST cut quartz substrate. Thus, it is possible to reduce the amount of frequency fluctuation with respect to temperature, and to provide a surface acoustic wave device having excellent temperature characteristics.

Next, a description will be given of a method for adjusting the temperature characteristics in the manufacturing process after forming the IDT electrodes by utilizing the fact that the temperature characteristics change depending on the logarithm of the IDT electrodes described above.
The surface acoustic wave device used in the present embodiment has the same configuration as that of the surface acoustic wave device 30 described in FIG. 5 of the first embodiment, and only the cut angle of the crystal substrate 31 is different.
The surface acoustic wave device 30 of the present embodiment has the cut angle and surface acoustic wave propagation direction of the quartz substrate 31 set to (0 °, 0 ° ≦ θ ≦ 180 °, 9 ° ≦ | ψ | ≦ 46 °), and the stop. Excites the upper band mode.

A procedure for adjusting temperature characteristics using such a surface acoustic wave device 30 will be described.
FIG. 11 is a flowchart for explaining the procedure of the temperature characteristic adjusting method in the surface acoustic wave device. Further, FIGS. 7 and 8 that describe the temperature characteristic adjusting method in the first embodiment will be described with reference to FIGS. Here, the temperature characteristic adjusting method will be described with reference to FIGS. 7 and 8 according to the flowchart of FIG.

First, in step S11, the temperature characteristics of the surface acoustic wave device 30 are measured. Next, in step S12, it is confirmed whether the primary temperature coefficient of the temperature characteristic is within a desired range based on the measured temperature characteristic. If the primary temperature coefficient of the temperature characteristic is not within the desired range, the process proceeds to step S13, and it is determined whether or not the measured primary temperature coefficient of the temperature characteristic is smaller than the desired range. If the primary temperature coefficient is larger than the desired range, the process proceeds to step S14 and the work for cutting the IDT electrode 32 is started.
Here, as shown in FIG. 7A, the IDT electrode 32 is cut from the both sides of the IDT electrode 32 along the cutting lines BB and CC along a desired logarithmic IDT electrode. In cutting the IDT electrode 32, the laser bars are irradiated to the bus bars 32a and 32c of the IDT electrode 32 to cut the bus bars 32a and 32c. By this cutting, the comb-shaped electrodes 41 and 42 having the electrode fingers connected to the bus bars 41a, 41c, 42a, and 42c are separated from the IDT electrode 32.
In order to maintain left-right symmetry about the IDT electrode 32 of the surface acoustic wave device 30, it is preferable to separate the same logarithm from both sides of the IDT electrode 32.

Next, it returns to step S11 and a temperature characteristic is measured again. Steps S12, S13, and S14 are repeated until the primary temperature coefficient falls within the desired range. When the primary temperature coefficient falls within the desired range at step S12, the temperature characteristics of the surface acoustic wave device are adjusted. Is completed and the process proceeds to step S16, and the operation of connecting the comb electrodes to the reflectors 33 and 34 is started.
As shown in FIG. 7B, the operation of connecting the comb electrodes to the reflectors 33 and 34 is performed by first adding a solution containing conductive particles between the reflector 33 and the bus bars 36a and 36c of the comb electrode 36 by an ink jet method. A droplet 45 made of is applied. Subsequently, a droplet 45 is applied between the bus bars 36a and 36c of the comb electrode 36 and the bus bars 35a and 35c of the comb electrode 35 by an ink jet method. Then, a droplet 45 is applied between the bus bars 35a and 35c of the comb electrode 35 and the bus bars 41a and 41c of the comb electrode 41 by an ink jet method.
Similarly, in the connection between the reflector 34 and the comb-shaped electrodes 38, 37, and 42, the droplet 45 is applied between the respective bus bars by the ink jet method.
After applying the droplet 45, the droplet 45 is dried, whereby the reflector 33 and the comb electrodes 36, 35, and 41 and the reflector 34 and the comb electrodes 38, 37, and 42 are connected. Complete.

If the first-order temperature coefficient is smaller than the desired range in step S13 of FIG. 11, the process proceeds to step S15 and the operation of connecting the comb electrode to the IDT electrode 32 is started.
The operation of connecting the comb electrodes is an operation of connecting the comb electrodes corresponding to the desired logarithm of the IDT electrodes to the IDT electrodes 32. As shown in FIG. 8A, first, a droplet 45 made of a solution containing conductive particles is applied between the bus bars 32a and 32c of the IDT electrode 32 and the bus bars 35a and 35c of the comb electrode 35 by an ink jet method. Next, a droplet 45 is applied between the bus bars 32 a and 32 c of the IDT electrode 32 and the bus bars 37 a and 37 c of the comb electrode 37 by an ink jet method. Thereafter, the droplet 45 is dried, whereby the IDT electrode 32 and the comb-shaped electrodes 35 and 37 are connected, and electrical conduction is made.
In order to maintain left-right symmetry about the IDT electrode 32 of the surface acoustic wave device 30, it is preferable to connect comb-shaped electrodes having the same logarithm from both sides of the IDT electrode 32.

  Next, it returns to step S11 and a temperature characteristic is measured again. Steps S11, S12, S13, and S15 are repeated until the primary temperature coefficient enters the desired range. When the primary temperature coefficient enters the desired range in step S12, the temperature characteristic adjustment of the surface acoustic wave device is completed. Then, the process proceeds to step S16, and the operation of connecting the comb electrodes to the reflectors 33 and 34 is started. As shown in FIG. 8B, the operation of connecting the comb electrodes to the reflectors 33 and 34 is as follows. First, a solution containing conductive particles between the reflector 33 and the bus bars 36a and 36c of the comb electrode 36 by an ink jet method. A droplet 45 made of is applied. Next, similarly, a droplet 45 is applied between the reflector 34 and the bus bars 38a, 38c of the comb-shaped electrode 38 by an ink jet method. Thereafter, by drying the droplet 45, the reflector 33 and the comb electrode 36 and the reflector 34 and the comb electrode 38 are connected, and the surface acoustic wave device 30 is completed.

As described above, in this embodiment, in the manufacturing process after forming the IDT electrode 32, the IDT electrode 32 is cut to reduce the logarithm of the IDT electrode 32, thereby reducing the primary temperature coefficient of the temperature characteristics. Then, the temperature characteristic curve can be adjusted to rotate right, and the temperature characteristic curve can be adjusted to rotate counterclockwise by increasing the first-order temperature coefficient of the temperature characteristic by connecting a comb electrode to the IDT electrode 32. can do.
Thus, the surface acoustic wave device 30 that uses the in-plane rotation ST-cut quartz substrate 31 and includes the single type IDT electrode 32 and excites the upper limit mode of the stopband of the surface acoustic wave is not conventionally known. The primary temperature coefficient of the temperature characteristic can be adjusted by changing the logarithm of the IDT electrode 32, and the temperature characteristic of the surface acoustic wave device 30 can be adjusted. Accordingly, variations in temperature characteristics in the manufacturing process can be suppressed, and a more stable surface acoustic wave device 30 can be obtained.
Further, by irradiating the IDT electrode 32 with laser light, the IDT electrode 32 can be easily cut, and the number of electrode fingers of the IDT electrode 32 can be reduced. Furthermore, the IDT electrode 32 and the comb electrode can be easily connected by applying a conductive material between the IDT electrode 32 and the comb electrode by an ink jet method.
Then, by connecting the comb electrodes to the reflectors 33 and 34, the comb electrodes can be used as a reflector, so that the reflection coefficient of the reflector can be increased, and the surface acoustic wave device 30 having good characteristics can be obtained. Can do.
Further, if the cut angle and surface acoustic wave propagation direction of the quartz substrate are (0 °, 95 ° ≦ θ ≦ 155 °, 33 ° ≦ | ψ | ≦ 46 °), the in-plane rotation ST-cut quartz substrate is used to stop. Compared with the case where the lower limit mode of the band is used, the amount of frequency fluctuation with respect to temperature can be reduced, and a surface acoustic wave device having excellent temperature characteristics can be provided.
(Third embodiment)

Next, a method for manufacturing the surface acoustic wave device will be described.
FIG. 12 is a flowchart for explaining the manufacturing process of the surface acoustic wave device.
In the method of manufacturing the surface acoustic wave device, first, a metal film such as Al is formed on the surface of the quartz substrate with a predetermined thickness, and the shape of the IDT electrode and the reflector is formed on the metal film using a photolithography technique. (Step S21). Next, the frequency of the surface acoustic wave device is adjusted by etching the electrode of the IDT electrode or etching the quartz substrate around the IDT electrode (step S22). Subsequently, the temperature characteristic of the surface acoustic wave device is adjusted by the temperature characteristic adjusting method described in the first embodiment and the second embodiment (step S23). In this way, the surface acoustic wave device is manufactured by flowing through each process.

  As described above, according to the method for manufacturing the surface acoustic wave device of this embodiment, the lower limit mode or the upper limit of the stop band of the surface acoustic wave using the in-plane rotating ST-cut quartz substrate and the single type IDT electrode is provided. In a surface acoustic wave device that excites a mode, by changing the logarithm of an IDT electrode that has not been known in the past, the apex temperature of the temperature characteristic or the first-order temperature coefficient of the temperature characteristic of a cubic function is adjusted, and the surface acoustic wave device The temperature characteristics of can be adjusted. In addition, with this crystal substrate cut angle, the amount of frequency fluctuation with respect to temperature can be reduced compared to the case of using an ST cut crystal substrate, and a method of manufacturing a surface acoustic wave device having excellent temperature characteristics is provided. it can.

  The present invention can be used for a SAW resonator or a resonator type surface acoustic wave filter as a surface acoustic wave device.

The figure for demonstrating Euler angle. It is explanatory drawing explaining the structure of a surface acoustic wave apparatus, (a) is a schematic plan view of a surface acoustic wave apparatus, (b) is a schematic cross section along the AA disconnection of the same figure (a). The graph which shows a temperature characteristic when using the ST cut quartz substrate and changing the logarithm of the IDT electrode. The graph which shows a temperature characteristic when using the in-plane rotation ST cut quartz substrate and changing the logarithm of the IDT electrode which excites a lower limit mode. It is a schematic diagram which shows the structure of the surface acoustic wave apparatus which concerns on 1st Embodiment, (a) is a schematic plan view, (b) is a schematic cross section along the AA disconnection of the same figure (a). The flowchart figure which shows the procedure of the temperature characteristic adjustment method which concerns on 1st Embodiment. The schematic plan view explaining the temperature characteristic adjustment method of 1st and 2nd embodiment. The schematic plan view explaining the temperature characteristic adjustment method of 1st and 2nd embodiment. The graph which shows the amount of frequency fluctuations of the surface acoustic wave apparatus in 2nd Embodiment, and board | substrate cutting-out angle (theta) and (psi). The graph which shows a temperature characteristic when using the in-plane rotation ST cut quartz substrate and changing the logarithm of the IDT electrode which excites the upper limit mode. The flowchart figure which shows the procedure of the temperature characteristic adjustment method which concerns on 2nd Embodiment. The flowchart figure explaining the manufacturing method of the surface acoustic wave apparatus in 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 30 ... Surface acoustic wave device, 31 ... Quartz substrate, 32 ... IDT electrode, 32b, 32d ... Electrode finger, 33, 34 ... Reflector, 35, 36, 37, 38 ... Comb electrode, 45 ... Liquid containing a conductive material drop.

Claims (21)

A single-type IDT electrode having a quartz substrate with Euler angles (0 °, 113 ° ≦ θ ≦ 135 °, 40 ° ≦ | ψ | ≦ 49 °) provided with a number of electrode fingers for exciting Rayleigh surface acoustic waves; A method of adjusting the temperature characteristics of a surface acoustic wave device comprising reflectors on both sides of the IDT electrode and exciting a lower limit mode of a stop band of the surface acoustic wave,
A temperature characteristic adjusting method for a surface acoustic wave device, wherein the logarithm of the IDT electrode is changed to adjust the apex temperature of the temperature characteristic in the surface acoustic wave device. In the temperature characteristic adjustment method of the surface acoustic wave device according to claim 1,
The surface acoustic wave device further includes a comb electrode between the IDT electrode and the reflector,
The IDT electrode is cut to reduce the number of IDT electrodes, or the IDT electrode is connected to the comb-shaped electrode to increase the number of IDT electrodes, thereby changing the number of IDT electrodes. Method for adjusting temperature characteristics of surface wave device. In the temperature characteristic adjustment method of the surface acoustic wave device according to claim 2,
Cutting the IDT electrode by irradiating a part of the IDT electrode with laser light,
A method of adjusting temperature characteristics of a surface acoustic wave device, wherein the number of electrode fingers of the IDT electrode is reduced. In the temperature characteristic adjustment method of the surface acoustic wave device according to claim 2,
A method for adjusting temperature characteristics of a surface acoustic wave device, wherein the IDT electrode and the comb electrode are connected by applying a conductive material by an ink jet method. A single-type IDT electrode in which a large number of electrode fingers for exciting Rayleigh surface acoustic waves are provided on a quartz substrate having an Euler angle (0 °, 0 ° ≦ θ ≦ 180 °, 9 ° ≦ | ψ | ≦ 46 °); A method for adjusting the temperature characteristics of a surface acoustic wave device comprising reflectors on both sides of the IDT electrode and exciting an upper limit mode of a stop band of the surface acoustic wave,
A temperature characteristic adjusting method for a surface acoustic wave device, wherein the logarithm of the IDT electrode is changed to adjust a first-order temperature coefficient of a temperature characteristic of a cubic function in the surface acoustic wave device. In the temperature characteristic adjustment method of the surface acoustic wave device according to claim 5,
A temperature characteristic adjusting method for a surface acoustic wave device, wherein the surface acoustic wave device has a Euler angle of (0 °, 95 ° ≦ θ ≦ 155 °, 33 ° ≦ | ψ | ≦ 46 °). In the temperature characteristic adjustment method of the surface acoustic wave device according to claim 5 or 6,
The surface acoustic wave device further includes a comb electrode between the IDT electrode and the reflector,
The IDT electrode is cut to reduce the number of IDT electrodes, or the IDT electrode is connected to the comb-shaped electrode to increase the number of IDT electrodes, thereby changing the number of IDT electrodes. Method for adjusting temperature characteristics of surface wave device. In the temperature characteristic adjustment method of the surface acoustic wave device according to claim 7,
Cutting the IDT electrode by irradiating a part of the IDT electrode with laser light,
A method for adjusting temperature characteristics of a surface acoustic wave device, wherein the logarithm of the IDT electrode is reduced. In the temperature characteristic adjustment method of the surface acoustic wave device according to claim 7,
A method for adjusting temperature characteristics of a surface acoustic wave device, wherein the IDT electrode and the comb electrode are connected by applying a conductive material by an ink jet method.   A surface acoustic wave device manufactured by the method for adjusting a temperature characteristic of a surface acoustic wave device according to any one of claims 1 to 9. The surface acoustic wave device according to claim 10,
A single type IDT electrode for exciting a Rayleigh type surface acoustic wave on a quartz substrate, a plurality of comb electrodes formed on both sides of the IDT electrode independently of the IDT electrodes, and a reflection formed on the outside of the comb electrode And equipped with
A surface acoustic wave device, wherein the IDT electrode and at least one of the comb electrodes are connected by a conductive material. The surface acoustic wave device according to claim 10,
A single type IDT electrode for exciting a Rayleigh type surface acoustic wave on a quartz substrate, a plurality of comb electrodes formed on both sides of the IDT electrode independently of the IDT electrodes, and a reflection formed on the outside of the comb electrode And equipped with
The surface acoustic wave device, wherein the reflector and at least one of the comb electrodes are connected by a conductive material. A single-type IDT electrode having a quartz substrate with Euler angles (0 °, 113 ° ≦ θ ≦ 135 °, 40 ° ≦ | ψ | ≦ 49 °) provided with a number of electrode fingers for exciting Rayleigh surface acoustic waves; A method of manufacturing a surface acoustic wave device that includes a step of forming reflectors disposed on both sides of the IDT electrode, and excites a lower limit mode of a stop band of the surface acoustic wave,
A method of manufacturing a surface acoustic wave device, comprising: a temperature characteristic adjusting step of adjusting a vertex temperature of a temperature characteristic in the surface acoustic wave device by changing a logarithm of the IDT electrode. In the manufacturing method of the surface acoustic wave device according to claim 13,
The surface acoustic wave device has a comb electrode between the IDT electrode and the reflector,
The temperature characteristic adjustment process changes the logarithm of the IDT electrode by cutting the IDT electrode and reducing the logarithm of the IDT electrode, or connecting the comb electrode to the IDT electrode and increasing the logarithm of the IDT electrode. A method for producing a surface acoustic wave device, characterized in that the method comprises: In the manufacturing method of the surface acoustic wave device according to claim 14,
The temperature characteristic adjusting step is a step of cutting the IDT electrode by irradiating a part of the IDT electrode with a laser beam to reduce the number of electrode fingers of the IDT electrode. Manufacturing method. In the manufacturing method of the surface acoustic wave device according to claim 14,
The method of manufacturing a surface acoustic wave device, wherein the temperature characteristic adjusting step is a step of connecting the IDT electrode and the comb electrode by applying a conductive material by an ink jet method. A single-type IDT electrode in which a large number of electrode fingers for exciting Rayleigh surface acoustic waves are provided on a quartz substrate having an Euler angle (0 °, 0 ° ≦ θ ≦ 180 °, 9 ° ≦ | ψ | ≦ 46 °); A method of manufacturing a surface acoustic wave device that includes a step of forming reflectors disposed on both sides of the IDT electrode, and excites an upper limit mode of a stop band of the surface acoustic wave,
A method of manufacturing a surface acoustic wave device, comprising: a temperature characteristic adjustment step of adjusting a first-order temperature coefficient of a temperature characteristic of a cubic function in the surface acoustic wave device by changing the logarithm of the IDT electrode. In the manufacturing method of the surface acoustic wave device according to claim 17,
A method of manufacturing a surface acoustic wave device, wherein the surface acoustic wave device has a Euler angle (0 °, 95 ° ≦ θ ≦ 155 °, 33 ° ≦ | ψ | ≦ 46 °). In the manufacturing method of the surface acoustic wave device according to claim 17 or 18,
The surface acoustic wave device has a comb electrode between the IDT electrode and the reflector,
The temperature characteristic adjustment process changes the logarithm of the IDT electrode by cutting the IDT electrode and reducing the logarithm of the IDT electrode, or connecting the comb electrode to the IDT electrode and increasing the logarithm of the IDT electrode. A method for producing a surface acoustic wave device, characterized in that the method comprises: In the manufacturing method of the surface acoustic wave device according to claim 19,
The temperature characteristic adjusting step is a step of cutting the IDT electrode by irradiating a part of the IDT electrode with laser light to reduce the logarithm of the IDT electrode. Method. In the manufacturing method of the surface acoustic wave device according to claim 19,
The method of manufacturing a surface acoustic wave device, wherein the temperature characteristic adjusting step is a step of connecting the IDT electrode and the comb electrode by applying a conductive material by an ink jet method.

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