JP4582150B2 - Surface acoustic wave device and module device or oscillation circuit using the same - Google Patents

Description

The present invention relates to a surface acoustic wave device using a quartz substrate and having a reduced capacitance ratio and improved frequency controllability.

In recent years, surface acoustic wave (SAW) devices have been widely used as components for mobile communication terminals and in-vehicle devices, and are small in size, high in Q value, and excellent in frequency temperature characteristics. There is a strong demand for it.

As a SAW device that realizes these requirements, there is a SAW device using an ST cut quartz substrate. The ST cut quartz substrate is a cut name of a quartz plate having a plane (XZ ′ plane) obtained by rotating the XZ plane by 42.75 ° counterclockwise from the crystal Z axis with the crystal X axis as the rotation axis. A SAW which is a (P + SV) wave called a propagating Rayleigh wave (hereinafter referred to as ST cut quartz SAW) is used. ST-cut quartz SAW devices have a wide range of applications, such as SAW resonators used as oscillation elements and IF filters arranged between the RF stage and the IC of mobile communication terminals.

The reason why ST-cut quartz SAW devices can realize small devices with high Q values is as follows:
The point which can utilize the reflection of SAW efficiently is mentioned. Hereinafter, the ST cut quartz SAW resonator shown in FIG. 11 will be described as an example. The ST-cut quartz SAW resonator is formed of an ST-cut quartz substrate 1
A comb-shaped electrode (hereinafter referred to as IDT) 102 having a plurality of electrode fingers that are interleaved with each other is disposed on 01, and grating reflectors 103a and 103b for reflecting SAW are disposed on both sides of IDT 102. It is a structure. Since the ST cut quartz SAW is a wave propagating along the surface of the piezoelectric substrate, it is efficiently reflected by the grating reflectors 103a and 103b, and the SAW energy can be sufficiently confined in the IDT 102.
A small device with a high Q value can be obtained.

Further, an important factor in using the SAW device is a frequency temperature characteristic. ST above
In the cut crystal SAW, the first-order temperature coefficient of the frequency temperature characteristic is zero, and the characteristic is 2
It is generally known that it is excellent in frequency stability because it is represented by the following curve and the amount of frequency fluctuation is remarkably reduced when the apex temperature is adjusted to be located at the center of the operating temperature range.

However, the ST cut quartz SAW device has zero primary temperature coefficient, but 2
Since the next temperature coefficient is relatively large as −0.034 (ppm / ° C. ² ), there is a problem that the amount of frequency fluctuation becomes extremely large when the operating temperature range is expanded.

As a technique for solving the problem, there are SAW devices disclosed in Non-Patent Document 1 and Patent Document 1. In this SAW device, as shown in FIG. 12, the cut angle θ of the rotated Y-cut quartz substrate is set in the vicinity of −50 ° rotated counterclockwise from the crystal Z axis, and the SAW propagation direction is set to the crystal X axis. In contrast, the vertical direction (Z′-axis direction) is characteristic. When the above cut angle is displayed in Euler angle, (0 °, θ + 90 °, 90 °) = (0 °, 40 °,
90 °). This SAW device uses an IDT to transmit SH waves that propagate just below the surface of a piezoelectric substrate.
The frequency temperature characteristic becomes a cubic curve, and the amount of frequency fluctuation in the operating temperature range is extremely small, so that a favorable frequency temperature characteristic can be obtained.

However, since the SH wave is basically a wave that travels in the substrate, it is compared with the ST cut quartz SAW that propagates along the surface of the piezoelectric substrate.
The reflection efficiency of AW is bad. Therefore, there is a problem that it is difficult to realize a small and high Q SAW device. Further, although the above-mentioned prior art document discloses the application as a delay line that does not use the SAW reflection, the application to the device using the SAW reflection has not been proposed. It was said that the practical use of was difficult.

In order to solve this problem, in Patent Document 2, as shown in FIG. 13, the cut angle θ of the rotated Y-cut quartz crystal substrate is set to around −50 °, and the SAW propagation direction is perpendicular to the crystal X axis (Z '
A so-called multiple QT is obtained by confining the SAW energy only by the reflection of the IDT 112 itself without using a grating reflector, by forming 800 ± 200 pairs of IDTs 112 on the piezoelectric substrate 111 in the axial direction). An anti-IDT SAW resonator is disclosed.

However, the multi-pair IDT SAW resonator is a SAW provided with a grating reflector.
Since an efficient energy confinement effect cannot be obtained as compared with the resonator, and the IDT logarithm necessary to obtain a high Q value becomes very large as 800 ± 200 pairs, the ST-cut quartz SAW
There is a problem that the device size becomes larger than that of the resonator, and the recent demand for miniaturization cannot be met.

In the SAW resonator disclosed in Patent Document 2, S excited by IDT is used.
When the wavelength of AW is λ, the Q value can be increased by setting the electrode film thickness to 2% λ or more, preferably 4% λ or less. The Q value reaches saturation, but the Q value at that time is only about 20000, and the ST cut crystal S
Even when compared with an AW resonator, only a substantially equivalent Q value can be obtained. This is because the film thickness is 2% λ.
In the range of 4% λ or less, SAW is not sufficiently collected on the surface of the piezoelectric substrate, so that reflection cannot be used efficiently.

Therefore, the present inventor disclosed in Patent Document 3 that the cut angle θ of the rotated Y-cut quartz substrate is −64.0 ° <θ <−49.3 °, preferably −61.4, counterclockwise from the crystal Z axis. ° <θ <-51
. An IDT made of Al or an alloy containing Al as a main component is formed on a quartz plate set in a range of 1 ° and having a surface acoustic wave propagation direction of 90 ° ± 5 ° with respect to the crystal X axis, The electrode film thickness H / λ normalized by the SAW wavelength of the IDT is 0.04 <H / λ <0.12, preferably 0.
. A SAW device with 05 <H / λ <0.10 was invented. According to the invention,
Since the wave traveling under the piezoelectric substrate can be concentrated on the surface of the substrate and SAW reflection can be efficiently used by a grating reflector or the like, the Q-value is smaller than that of a conventional ST-cut quartz SAW device. And a SAW device with excellent frequency temperature characteristics can be realized.

Japanese Examined Patent Publication No. 62-016050 Japanese Patent Publication No. 01-034411 International Publication No. WO2005 / 099089A1 Pamphlet Meirion Lewis, “Surface Skimming Bulk Wave, SSBW”, IEEE Ultrasonics Symp. Proc., Pp. 744–752 (1977)

Incidentally, in SAW devices such as SAW resonators and SAW filters, there is a capacitance ratio γ as an important parameter for determining characteristics. FIG. 14 shows an equivalent circuit of the SAW resonator, and the capacity ratio γ can be expressed by γ = C0 / C1. The smaller the capacitance ratio γ, the easier the oscillation in the oscillation circuit using the SAW resonator, and the greater the variable range of the oscillation frequency.
The AW filter has an advantage that a realizable bandwidth can be widened.

The capacity ratio γ may vary greatly depending on the ratio of the electrode finger width L to the electrode pitch (electrode finger width L + electrode finger space S) of the IDT (hereinafter referred to as the line occupation ratio mr). Therefore, if the IDT line occupancy ratio mr is not properly selected, the capacity ratio γ increases and the desired characteristics may not be obtained. However, in Patent Document 3, the capacity ratio γ is not mentioned, and it is necessary to examine in detail the relationship between the capacity ratio γ and the line occupation ratio mr.

Further, in the SAW device manufacturing process, it is difficult to accurately control the line occupancy ratio mr, and variations occur due to manufacturing errors and measurement errors during electrode formation. If the line occupancy ratio mr varies, frequency fluctuations occur and the manufacturing yield deteriorates. Therefore, it is necessary to appropriately select the line occupation ratio mr excellent in frequency controllability.
Does not mention frequency controllability, and the relationship between the line occupancy ratio mr and frequency controllability needs to be examined in detail.

The present invention has been made to solve the above-described problems, and achieves downsizing, high Q, and excellent frequency temperature characteristics in a SAW device using a quartz substrate as a piezoelectric substrate and utilizing SH waves. At the same time, it is an object to provide a SAW device in which the capacity ratio γ is reduced and the frequency controllability is improved.

In order to solve the above problems, the invention of the application example 1 of the SAW device according to the present invention includes a piezoelectric substrate and an IDT formed on the piezoelectric substrate and made of Al or an alloy containing Al as a main component. Is a surface acoustic wave device having a SH wave, and the piezoelectric substrate has a cut angle θ of the rotated Y-cut quartz substrate of −61.4 ° <θ <−51.1 ° counterclockwise from the crystal Z axis. This is a quartz plate that is set to a range and the propagation direction of the surface acoustic wave is 90 ° ± 5 ° with respect to the crystal X axis, and the wavelength of the exciting surface acoustic wave is λ, and the reference is the wavelength of the IDT. The electrode thickness H / λ is 0.04 <H / λ <0.12, and the line occupation ratio mr of the electrode fingers constituting the IDT is electrode finger width / (electrode finger width + electrode finger space). When the line occupancy rate mr is 0.53 ≦ mr ≦ 0.65, And butterflies.
Further, the piezoelectric substrate is rotated such that the cut angle θ is a rotation angle of the crystal Z axis with the crystal X axis as the rotation axis, and the cut angle θ is negative in the direction of rotation from the crystal + Z axis to the crystal + Y axis side. Rotational Y-cut consisting of a quartz plate with a direction set in the range of −61.4 ° <θ <−51.1 ° and the propagation direction of the surface acoustic wave being 90 ° ± 5 ° with respect to the crystal X axis It may be a quartz substrate.
According to a certain form, in application example 1, −8.04489 × 10 ⁻⁵ × θ ³ −1.40981 × 10 ⁻² × θ ² −0.825038 × θ−16.0737 <H / λ × mr <−6.15517 × 10 ⁻⁵ × θ ³ −1.03943 × 10 ⁻² × θ ² −0.586564 × θ-11.0052, and −8.66762 × 10 ⁻⁵ × θ ³ −1.504014 × 10 ⁻² × θ ² −0.870514 × θ−16.7678 <H / λ × mr <−5.992554 × 10 ⁻⁵ × θ ³ −1.02183 × 10 ⁻² × θ ² The range satisfying −0.588704 × θ−11.2768 is excluded.
According to Application Example 1, the cut angle θ of the rotated Y-cut quartz substrate is set in the range of −61.4 ° <θ <−51.1 ° counterclockwise from the crystal Z axis, and the surface acoustic wave An IDT made of Al or an alloy containing Al as a main component is formed on a quartz plate whose propagation direction is 90 ° ± 5 ° with respect to the crystal X axis, and the electrode thickness H is normalized by the SAW wavelength of the IDT. In a SAW device in which / λ is 0.04 <H / λ <0.12, the capacitance ratio γ can be reduced by setting the line occupation ratio mr of the IDT to 0.53 ≦ mr ≦ 0.65. It is. As a result, downsizing, high Q, and excellent frequency temperature characteristics can be realized, and the bandwidth that can be realized with a SAW filter can be widened, and an oscillation circuit using a SAW resonator can easily oscillate. There are effects such as a large variable frequency range. Further, since the cut angle θ is set in the range of −61.4 <θ <−51.1, the vertex temperature Tp (° C.) can be set in a practical temperature range.

The invention of Application Example 2 is a surface acoustic wave device including a piezoelectric substrate and an IDT formed on the piezoelectric substrate and made of Al or an alloy containing Al as a main component, and an excitation wave is an SH wave. In the piezoelectric substrate, the cut angle θ of the rotated Y-cut quartz substrate is set in the range of −61.4 ° <θ <−51.1 ° counterclockwise from the crystal Z axis, and the propagation direction of the surface acoustic wave is set A crystal flat plate with 90 ° ± 5 ° with respect to the crystal X axis, where the wavelength of the surface acoustic wave to be excited is λ, the electrode film thickness H / λ normalized by the wavelength of the IDT is 0.04 <H /Λ<0.12 and when line occupancy ratio mr of electrode fingers constituting the IDT is electrode finger width / (electrode finger width + inter-electrode finger space), the line occupancy ratio mr is 0.55 ≦ mr. It is characterized in that ≦ 0.68.
Further, the piezoelectric substrate is rotated such that the cut angle θ is a rotation angle of the crystal Z axis with the crystal X axis as the rotation axis, and the cut angle θ is negative in the direction of rotation from the crystal + Z axis to the crystal + Y axis side. Rotational Y-cut consisting of a quartz plate with a direction set in the range of −61.4 ° <θ <−51.1 ° and the propagation direction of the surface acoustic wave being 90 ° ± 5 ° with respect to the crystal X axis It may be a quartz substrate.
According to a certain form, in application example 2, −8.04489 × 10 ⁻⁵ × θ ³ −1.40981 × 10 ⁻² × θ ² −0.825038 × θ−16.0737 <H / λ × mr <−6.15517 × 10 ⁻⁵ × θ ³ −1.03943 × 10 ⁻² × θ ² −0.586564 × θ-11.0052, and −8.66762 × 10 ⁻⁵ × θ ³ −1.504014 × 10 ⁻² × θ ² −0.870514 × θ−16.7678 <H / λ × mr <−5.992554 × 10 ⁻⁵ × θ ³ −1.02183 × 10 ⁻² × θ ² The range satisfying −0.588704 × θ−11.2768 is excluded.
According to Application Example 2, the cut angle θ of the rotated Y-cut quartz substrate is set in the range of −61.4 ° <θ <−51.1 ° counterclockwise from the crystal Z axis, and the surface acoustic wave An IDT made of Al or an alloy containing Al as a main component is formed on a quartz plate whose propagation direction is 90 ° ± 5 ° with respect to the crystal X axis, and the electrode thickness H is normalized by the SAW wavelength of the IDT. In the SAW device in which / λ is 0.04 <H / λ <0.12, the line occupancy ratio mr of the IDT is 0.55 ≦ mr ≦ 0.68, so that the frequency controllability can be improved. As a result, even if the line occupancy ratio mr varies during the manufacture of the SAW device, the frequency fluctuation amount can be suppressed, so that it is possible to reduce the manufacturing difficulty and the manufacturing cost of the SAW device. Further, since the cut angle θ is set in the range of −61.4 <θ <−51.1, the vertex temperature Tp (° C.) can be set in a practical temperature range.

The invention of application example 3 is a surface acoustic wave device including a piezoelectric substrate and an IDT formed on the piezoelectric substrate and made of Al or an alloy containing Al as a main component, and an excitation wave is an SH wave. In the piezoelectric substrate, the cut angle θ of the rotated Y-cut quartz substrate is set in the range of −61.4 ° <θ <−51.1 ° counterclockwise from the crystal Z axis, and the propagation direction of the surface acoustic wave is set A crystal flat plate with 90 ° ± 5 ° with respect to the crystal X axis, where the wavelength of the surface acoustic wave to be excited is λ, the electrode film thickness H / λ normalized by the wavelength of the IDT is 0.04 <H /Λ<0.12 and when line occupancy ratio mr of electrode fingers constituting the IDT is electrode finger width / (electrode finger width + inter-electrode finger space), the line occupancy ratio mr is 0.55 ≦ mr. It is characterized by being ≦ 0.65.
Further, the piezoelectric substrate is rotated such that the cut angle θ is a rotation angle of the crystal Z axis with the crystal X axis as the rotation axis, and the cut angle θ is negative in the direction of rotation from the crystal + Z axis to the crystal + Y axis side. Rotational Y-cut consisting of a quartz plate with a direction set in the range of −61.4 ° <θ <−51.1 ° and the propagation direction of the surface acoustic wave being 90 ° ± 5 ° with respect to the crystal X axis It may be a quartz substrate.
According to a certain form, in application example 3, −8.04489 × 10 ⁻⁵ × θ ³ −1.40981 × 10 ⁻² × θ ² −0.825038 × θ−16.0737 <H / λ × mr <−6.15517 × 10 ⁻⁵ × θ ³ −1.03943 × 10 ⁻² × θ ² −0.586564 × θ-11.0052, and −8.66762 × 10 ⁻⁵ × θ ³ −1.504014 × 10 ⁻² × θ ² −0.870514 × θ−16.7678 <H / λ × mr <−5.992554 × 10 ⁻⁵ × θ ³ −1.02183 × 10 ⁻² × θ ² The range satisfying −0.588704 × θ−11.2768 is excluded.
According to Application Example 3, the cut angle θ of the rotated Y-cut quartz substrate is set in the range of −61.4 ° <θ <−51.1 ° counterclockwise from the crystal Z axis, and the surface acoustic wave An IDT made of Al or an alloy containing Al as a main component is formed on a quartz plate whose propagation direction is 90 ° ± 5 ° with respect to the crystal X axis, and the electrode thickness H is normalized by the SAW wavelength of the IDT. In the SAW device in which / λ is 0.04 <H / λ <0.12, the line occupation ratio mr of the IDT is 0.55 ≦ H / λ ≦ 0.65, so that the optimum capacity ratio γ and frequency It is possible to provide a SAW device having both controllability. Further, since the cut angle θ is set in the range of −61.4 <θ <−51.1, the vertex temperature Tp (° C.) can be set in a practical temperature range.

The invention of Application Example 4 is characterized in that the electrode film thickness H / λ is set in a range of 0.04 <H / λ ≦ 0.08. It is characterized by being a surface acoustic wave device. According to Application Example 4, the electrode film thickness H / λ is 0.04 <H / λ ≦ 0.0.
By setting the value to 8, the Q value can be further increased.

The invention of application example 5 is a surface acoustic wave device including a piezoelectric substrate and an IDT formed on the piezoelectric substrate and made of Al or an alloy containing Al as a main component, and an excitation wave is an SH wave. In the piezoelectric substrate, the cut angle θ of the rotated Y-cut quartz substrate is set in the range of −64.0 ° <θ <−49.3 ° counterclockwise from the crystal Z axis, and the propagation direction of the surface acoustic wave is set. It is a quartz plate with 90 ° ± 5 ° with respect to the crystal X axis, and when the wavelength of the surface acoustic wave to be excited is λ, the electrode film thickness H / λ normalized by the wavelength of the IDT is 0.05 <H /Λ<0.10, and when the line occupancy ratio mr of the electrode fingers constituting the IDT is electrode finger width / (electrode finger width + inter-electrode finger space), the line occupancy ratio mr is 0.53 ≦ mr. It is characterized by being ≦ 0.65.
Further, the piezoelectric substrate is rotated such that the cut angle θ is a rotation angle of the crystal Z axis with the crystal X axis as the rotation axis, and the cut angle θ is negative in the direction of rotation from the crystal + Z axis to the crystal + Y axis side. Rotation Y cut made of a quartz plate with a direction set in the range of −64.0 ° <θ <−49.3 ° and the propagation direction of the surface acoustic wave being 90 ° ± 5 ° with respect to the crystal X axis It may be a quartz substrate.
According to a certain form, in application example 5, −8.04487 × 10 ⁻⁵ × θ ³ −1.40981 × 10 ⁻² × θ ² −0.825038 × θ−16.0737 <H / λ × mr <−6.15517 × 10 ⁻⁵ × θ ³ −1.03943 × 10 ⁻² × θ ² −0.586564 × θ-11.0052, and −8.66762 × 10 ⁻⁵ × θ ³ −1.504014 × 10 ⁻² × θ ² −0.870514 × θ−16.7678 <H / λ × mr <−5.992554 × 10 ⁻⁵ × θ ³ −1.02183 × 10 ⁻² × θ ² The range satisfying −0.588704 × θ−11.2768 is excluded.
According to Application Example 5, the cut angle θ of the rotated Y-cut quartz substrate is set in the range of −64.0 ° <θ <−49.3 ° counterclockwise from the crystal Z axis, and the surface acoustic wave An IDT made of Al or an alloy containing Al as a main component is formed on a quartz plate whose propagation direction is 90 ° ± 5 ° with respect to the crystal X axis, and the electrode thickness H is normalized by the SAW wavelength of the IDT. In the SAW device where / λ is 0.05 <H / λ <0.10, the capacity ratio γ can be reduced because the line occupation ratio mr of the IDT is 0.53 ≦ mr ≦ 0.65. As a result, downsizing, high Q, and excellent frequency temperature characteristics can be realized, and the bandwidth that can be realized with a SAW filter can be widened, and an oscillation circuit using a SAW resonator can easily oscillate. There are effects such as a large variable frequency range. Further, the Q value can be further increased by setting the electrode film thickness H / λ to 0.05 <H / λ <0.10.

The invention of application example 6 is a surface acoustic wave device including a piezoelectric substrate and an IDT formed on the piezoelectric substrate and made of Al or an alloy containing Al as a main component, and an excitation wave is an SH wave. In the piezoelectric substrate, the cut angle θ of the rotated Y-cut quartz substrate is set in the range of −64.0 ° <θ <−49.3 ° counterclockwise from the crystal Z axis, and the propagation direction of the surface acoustic wave is set. It is a quartz plate with 90 ° ± 5 ° with respect to the crystal X axis, and when the wavelength of the surface acoustic wave to be excited is λ, the electrode film thickness H / λ normalized by the wavelength of the IDT is 0.05 <H /Λ<0.10, and when the line occupancy ratio mr of electrode fingers constituting the IDT is electrode finger width / (electrode finger width + inter-electrode finger space), the line occupancy ratio mr is 0.55 ≦ mr. It is characterized in that ≦ 0.68.
Further, the piezoelectric substrate is rotated such that the cut angle θ is a rotation angle of the crystal Z axis with the crystal X axis as the rotation axis, and the cut angle θ is negative in the direction of rotation from the crystal + Z axis to the crystal + Y axis side. Rotation Y cut made of a quartz plate with a direction set in the range of −64.0 ° <θ <−49.3 ° and the propagation direction of the surface acoustic wave being 90 ° ± 5 ° with respect to the crystal X axis It may be a quartz substrate.
According to a certain form, in application example 6, −8.04489 × 10 ⁻⁵ × θ ³ −1.40981 × 10 ⁻² × θ ² −0.825038 × θ−16.0737 <H / λ × mr <−6.15517 × 10 ⁻⁵ × θ ³ −1.03943 × 10 ⁻² × θ ² −0.586564 × θ-11.0052, and −8.66762 × 10 ⁻⁵ × θ ³ −1.504014 × 10 ⁻² × θ ² −0.870514 × θ−16.7678 <H / λ × mr <−5.992554 × 10 ⁻⁵ × θ ³ −1.02183 × 10 ⁻² × θ ² The range satisfying −0.588704 × θ−11.2768 is excluded.
According to Application Example 6, the cut angle θ of the rotated Y-cut quartz substrate is set in the range of −64.0 ° <θ <−49.3 ° counterclockwise from the crystal Z axis, and the surface acoustic wave An IDT made of Al or an alloy containing Al as a main component is formed on a quartz plate whose propagation direction is 90 ° ± 5 ° with respect to the crystal X axis, and the electrode thickness H is normalized by the SAW wavelength of the IDT. In the SAW device in which / λ is 0.05 <H / λ <0.10, the line occupancy ratio mr of the IDT is 0.55 ≦ mr ≦ 0.68, so that the frequency controllability can be improved. As a result, even if the line occupancy ratio mr varies during the manufacture of the SAW device, the frequency fluctuation amount can be suppressed, so that it is possible to reduce the manufacturing difficulty and the manufacturing cost of the SAW device. Further, the Q value can be further increased by setting the electrode film thickness H / λ to 0.05 <H / λ <0.10.

The invention of application example 7 is a surface acoustic wave device including a piezoelectric substrate and an IDT formed on the piezoelectric substrate and made of Al or an alloy containing Al as a main component, and an excitation wave is an SH wave. In the piezoelectric substrate, the cut angle θ of the rotated Y-cut quartz substrate is set in the range of −64.0 ° <θ <−49.3 ° counterclockwise from the crystal Z axis, and the propagation direction of the surface acoustic wave is set. It is a quartz plate with 90 ° ± 5 ° with respect to the crystal X axis, and when the wavelength of the surface acoustic wave to be excited is λ, the electrode film thickness H / λ normalized by the wavelength of the IDT is 0.05 <H /Λ<0.10, and when the line occupancy ratio mr of electrode fingers constituting the IDT is electrode finger width / (electrode finger width + inter-electrode finger space), the line occupancy ratio mr is 0.55 ≦ mr. It is characterized by being ≦ 0.65.
Further, the piezoelectric substrate is rotated such that the cut angle θ is a rotation angle of the crystal Z axis with the crystal X axis as the rotation axis, and the cut angle θ is negative in the direction of rotation from the crystal + Z axis to the crystal + Y axis side. Rotation Y cut made of a quartz plate with a direction set in the range of −64.0 ° <θ <−49.3 ° and the propagation direction of the surface acoustic wave being 90 ° ± 5 ° with respect to the crystal X axis It may be a quartz substrate.
According to a certain form, in application example 7, −8.04489 × 10 ⁻⁵ × θ ³ −1.40981 × 10 ⁻² × θ ² −0.825038 × θ−16.0737 <H / λ × mr <−6.15517 × 10 ⁻⁵ × θ ³ −1.03943 × 10 ⁻² × θ ² −0.586564 × θ-11.0052, and −8.66762 × 10 ⁻⁵ × θ ³ −1.504014 × 10 ⁻² × θ ² −0.870514 × θ−16.7678 <H / λ × mr <−5.992554 × 10 ⁻⁵ × θ ³ −1.02183 × 10 ⁻² × θ ² The range satisfying −0.588704 × θ−11.2768 is excluded.
According to Application Example 7, the cut angle θ of the rotated Y-cut quartz substrate is set in the range of −64.0 ° <θ <−49.3 ° counterclockwise from the crystal Z axis, and the surface acoustic wave An IDT made of Al or an alloy containing Al as a main component is formed on a quartz plate whose propagation direction is 90 ° ± 5 ° with respect to the crystal X axis, and the electrode thickness H is normalized by the SAW wavelength of the IDT. In the SAW device in which / λ is 0.05 <H / λ <0.10, since the line occupation ratio mr of the IDT is 0.55 ≦ H / λ ≦ 0.65, the optimum capacitance ratio γ and frequency It is possible to provide a SAW device having both controllability. Further, the Q value can be further increased by setting the electrode film thickness H / λ to 0.05 <H / λ <0.10.

The invention of application example 8 is characterized in that the electrode film thickness H / λ is set in a range of 0.05 <H / λ ≦ 0.08. It is characterized by being a surface acoustic wave device. According to Application Example 8, the electrode film thickness H / λ is 0.05 <H / λ ≦ 0.0.
By setting the value to 8, the Q value can be further increased.

Inventions 9 and 10 are module devices or oscillation circuits characterized by using the surface acoustic wave device according to any one of claims 1 to 8.
According to Application Examples 9 and 10, since the SAW device is used for a module device or an oscillation circuit, a small and high-performance module device or an oscillation circuit can be provided.

Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings. FIG. 1A is a plan view of a SAW resonator according to the present invention. An IDT 2 in which a positive electrode finger and a negative electrode finger are inserted on a piezoelectric substrate 1 and a SAW on both sides of the IDT 2 are shown. The grating reflectors 3a and 3b for reflecting the light are disposed. And the input / output pad 4a of the IDT 2
4b and the input / output terminals of the package 6 are electrically connected by metal wires 5a and 5b,
The opening of the package 6 is hermetically sealed with a lid. In the piezoelectric substrate 1, the cut angle θ of the rotated Y-cut quartz substrate is set in the vicinity of −50 ° rotated counterclockwise from the crystal Z axis, and the SAW propagation direction is substantially perpendicular to the crystal X axis (90 ° ± The SAW to be excited is a SH wave. Note that the electrode materials of the IDT 2 and the grating reflectors 3a and 3b are Al or an alloy containing Al as a main component. FIG. 1B shows a cross-sectional view of the IDT 2. In the embodiment shown below, when the wavelength of the SAW excited on the IDT 2 is λ, the electrode thickness is normalized by the wavelength H / λ. The line occupancy ratio mr is represented by electrode finger width L / (electrode finger width L + electrode finger space S).

In the present invention, the electrode film thickness H / λ is set larger than in the past in view of the conventional drawbacks, so that the SAW can be concentrated on the surface of the piezoelectric substrate and the reflection of the SAW can be efficiently utilized by the grating reflector. The device size was reduced by confining the SAW energy in the IDT even with a small number of IDT logarithms and the number of grating reflectors.

In general, the optimum design of a SAW resonator is important in that it has excellent frequency temperature characteristics, a high Q and a small capacitance ratio γ, that is, a large figure of merit (Q / γ). Here, various characteristics of the SAW resonator of the present invention were examined. FIG. 2 shows a resonance frequency of the SAW resonator shown in FIG. 1 using a -51 ° rotated Y-cut 90 ° X propagation quartz substrate (Eulerian angle display (0 °, 39 °, 90 °)) as the piezoelectric substrate 1. Is 315 MHz, the electrode thickness H / λ is 0.06, the logarithm of IDT2 is 100 pairs, and the number of grating reflectors 3a and 3b is 1 each.
The characteristics of the resonator in the case of 00 are shown. (A) shows the Q value, figure of meri
t The secondary temperature coefficient is shown in (b), and the frequency temperature characteristic is shown on the basis of the actual prototype results. For comparison, various characteristics of an ST cut quartz SAW resonator having the same piezoelectric substrate size are also shown as conventional products.

FIG. 2 shows a comparison between the SAW resonator of the present invention and the conventional ST-cut quartz crystal SAW resonator.
The Q value is a little over 1.8 times and the figure of merit is about twice as large. As for the frequency temperature characteristics, it was confirmed that the apex temperature Tp was about + 25 ° C., which is a normal temperature, and the secondary temperature coefficient was reduced to about 0.6 times the conventional temperature coefficient.

Furthermore, the SAW resonator of the present invention can reduce the size of the piezoelectric substrate while maintaining a better Q value than the conventional ST cut quartz SAW resonator. This is because the increase in SAW reflection amount at the IDT or grating reflector with respect to the increase in the electrode film thickness H / λ of the SAW resonator of the present invention is
This is because it is significantly larger than the ST cut quartz SAW resonator. That is, S of the present invention
By increasing the electrode film thickness H / λ, the AW resonator can realize a high Q value with a smaller number of IDT pairs or grating reflectors than the ST-cut quartz SAW resonator.

FIG. 3 (a) shows the relationship between the electrode film thickness H / λ and the Q value in the SAW resonator of the present invention, and the resonator design conditions are the same as described above. From the figure, it can be seen that a value exceeding the Q value (= 15000) of the ST cut quartz SAW resonator can be obtained in the range of 0.04 <H / λ <0.12. Furthermore, 2000 is set by setting 0.05 <H / λ <0.10.
A high Q value of 0 or more can be obtained.

Further, when comparing the Q values of the many-pair IDT SAW resonator in Patent Document 2 and the SAW resonator of the present invention, the Q value obtained in Patent Document 2 is a value at a resonance frequency of 207.561 (MHz). When this is converted to the resonance frequency 315 (MHz) applied in the present embodiment, the Q value is about 15000, which is almost equivalent to the ST-cut quartz SAW resonator. Further, when comparing the sizes of the resonators, the many-to-one IDT SAW resonator disclosed in Patent Document 2 is 800 ± 20.
The logarithm of 0 pairs is required, whereas in the present invention, both IDT and grating reflectors are 20
Since the size of 0 pairs is sufficient, the size can be significantly reduced. Therefore, the electrode film thickness is 0.04 <H.
/Λ<0.12, preferably 0.05 <H / λ <0.10, and a grating reflector is provided to efficiently reflect SAW, so that the Vs. I
A SAW device that is smaller and has a higher Q value than a DT type SAW resonator can be realized.

FIG. 3B shows the relationship between the electrode film thickness H / λ and the secondary temperature coefficient in the SAW resonator of the present invention, and the resonator design conditions are the same as described above. From the figure, it is possible to obtain a high Q value.
. The secondary temperature coefficient of ST cut quartz SAW resonator in the range of 04 <H / λ <0.12−
It can be seen that a value better than 0.034 (ppm / ° C. ² ) can be obtained.

From the above, by setting the electrode film thickness H / λ in the range of 0.04 <H / λ <0.12, S
It was confirmed that a SAW device having a smaller size, a higher Q value, and excellent frequency stability than the T-cut quartz SAW device and the SAW device disclosed in Patent Document 2 can be provided.

Although only the case where the cut angle θ is set to −51 ° has been shown so far, in the SAW resonator of the present invention, the film thickness dependency does not change greatly even when the cut angle θ is changed, and from −51 °. The electrode film thickness is 0.04 <H / λ <0.12, preferably 0 even at a cut angle shifted by several degrees.
. It was confirmed that a good Q value and a secondary temperature coefficient were obtained by setting in the range of 05 <H / λ <0.10.

By the way, the apex temperature Tp of the frequency temperature characteristic of the SAW resonator varies depending on the electrode film thickness H / λ and the cut angle θ of the piezoelectric substrate. Therefore, even if the frequency temperature characteristic is excellent, if the apex temperature Tp is out of the operating temperature range, the frequency stability is significantly deteriorated, so that excellent frequency stability is realized in a practical operating temperature range. Therefore, it is necessary to examine not only the secondary temperature coefficient but also the apex temperature Tp in detail.

FIG. 4 shows the top temperature T in the SAW resonator based on the results of various prototype experiments described above.
FIG. 6 shows simulation results for calculating the relationship between the crystal substrate cut angle θ and the electrode film thickness H / λ when p (° C.) is Tp = −50, 0, +70, +125, and approximates each Tp characteristic. The formula is as follows.
Tp = −50 (° C.): H / λ≈−1.02586 × 10 ⁻⁴ × θ ³ −1.73238 × 10 ⁻² × θ ² −0.977607 ×
θ-18.3420
Tp = 0 (° C.): H / λ≈−9.87591 × 10 ⁻⁵ × θ ³ −1.70304 × 10 ⁻² × θ ² −0.981173 × θ
−18.7946
Tp = + 70 (° C.): H / λ≈−1.44605 × 10 ⁻⁴ × θ ³ −2.50690 × 10 ⁻² × θ ² −1.45086 ×
θ-27.9464
Tp = + 125 (° C.): H / λ≈−1.34082 × 10 ⁻⁴ × θ ³ −2.34969 × 10 ⁻² × θ ² −1.3750
6 × θ−26.7895

From FIG. 4, in order to set the apex temperature Tp (° C.) to a practical range of −50 ≦ Tp ≦ + 125, the region surrounded by the curves of Tp = −50 ° C. and Tp = + 125 ° C., that is, − 1.34082
× 10 ^-4 × θ ³ −2.34969 × 10 ⁻² × θ ² −1.37506 × θ−26.7895 <H / λ <−1.02586 × 10 ^-4 ×
It can be seen that the cut angle θ and the electrode film thickness H / λ may be set so that θ ³ −1.73238 × 10 ⁻² × θ ² −0.977607 × θ−18.3420. Note that the range of the electrode film thickness H / λ at this time is 0.04 <H / λ <0.12 in which characteristics superior to those of the conventional ST-cut quartz crystal device can be obtained, and the range of the cut angle θ is as shown in FIG. It is assumed that -64.0 ° <θ <−49.3 ° in the range shown from point A to point B.

Further, considering more optimal conditions, it is desirable to set the vertex temperature Tp (° C.) to 0 ≦ Tp ≦ + 70, which is a more practical use temperature range. In order to set Tp (° C.) within the aforementioned range, the region surrounded by the curves of Tp = 0 ° C. and Tp = + 70 ° C. shown in FIG.
44605 × 10 ⁻⁴ × θ ³ −2.50690 × 10 ⁻² × θ ² −1.45086 × θ−27.9464 <H / λ <−9.87591 × 1
The cut angle θ and the electrode film thickness H / λ may be set so that 0 ⁻⁵ × θ ³ −1.70304 × 10 ⁻² × θ ² −0.981173 × θ−18.7946. The electrode film thickness H / λ is preferably in the range of 0.05 <H / λ <0.10 where a Q value of 20000 or more can be obtained. The electrode film thickness is in the above range, and the apex temperature Tp (° C.). Is set within the range of 0 ≦ Tp ≦ + 70, the cut angle θ is set to the point C in FIG.
To −61.4 ° <θ <−51.1 ° in the range indicated by point D.

As a result of detailed examination, the rotated Y-cut quartz substrate having a cut angle θ in the range of −64.0 ° <θ <−49.3 °, preferably −61.4 ° <θ <−51.1 °. The electrode material of the IDT and the grating reflector is made of Al or an alloy mainly composed of Al, using the SH wave excited with the SAW propagation direction substantially perpendicular to the X axis, and the electrode film Thickness H /
By setting λ to 0.04 <H / λ <0.12, preferably 0.05 <H / λ <0.10, temperature characteristics with a larger Q value than ST-cut quartz SAW devices can be obtained. It has been confirmed that the apex temperature Tp can be set within a practical use temperature range.

Next, the relationship between the line occupation ratio mr of the SAW resonator and the capacity ratio γ was examined. As described above, the smaller the capacity ratio γ, the higher the performance of the device becomes possible.
It varies depending on the value of the line occupation ratio mr of DT. Therefore, it is necessary to select the line occupation rate mr of the IDT so that the optimum capacity ratio γ can be obtained.

FIG. 5A shows the relationship between the line occupancy mr of the SAW resonator and the capacitance ratio γ.
This figure shows experimental values. In the experiment, the cut angle θ of the quartz substrate was set to −52.0 °, and the electrode thickness H /
λ is changed in increments of 0.01 from 0.04 to 0.08, and the line occupation ratio mr of the IDT is 0.
. It was changed in increments of 0.1 from 4 to 0.8. Note that the line occupancy of the grating reflector at this time is changed in the same manner as in the IDT. From the figure, it can be seen that the capacity ratio γ shows a downwardly convex quadratic curve tendency with respect to the line occupation ratio mr.

FIG. 5B shows the value of the line occupancy ratio mr at which the capacity ratio γ is minimized under the conditions of each electrode film thickness H / λ, and the electrode film thickness H / λ is 0.04 ≦ H / λ. When ≦ 0.08, it was confirmed that the capacity ratio γ becomes almost the minimum value by setting the line occupation ratio mr to 0.58 ≦ mr ≦ 0.60. It should be noted that the line occupation ratio mr is actually set to 0. 0 from the curve of FIG.
By setting the range 53 ≦ mr ≦ 0.65, the capacity ratio γ can be sufficiently reduced.

As described above, in the SAW device of the present invention, the line occupation rate mr of the IDT is 0.53 ≦ m
It was confirmed that, by setting r ≦ 0.65, a small and high Q value and an excellent frequency temperature characteristic can be realized, and the capacitance ratio γ can be reduced.

By the way, the line occupation ratio mr is difficult to control accurately because of manufacturing errors and the like. If the line occupancy ratio mr varies, there is a problem that the manufacturing yield deteriorates because the frequency fluctuates. Therefore, it is desirable to select a line occupancy mr that has a small amount of frequency fluctuation even if the line occupancy mr varies, that is, excellent in frequency controllability. Hereinafter, the line occupation ratio mr and frequency controllability were examined.

FIG. 6A shows the relationship between the line occupation ratio mr of the SAW resonator and the resonance frequency f. This figure shows experimental values, the cut angle θ of the quartz substrate is −52.0 °, and the electrode film thickness H / λ is 0.
. The IDT line occupancy mr is changed from 0.4 to 0.08 in increments of 0.01, and is changed from 0.4 to 0.8 in increments of 0.1. Note that the line occupancy of the grating reflector at this time is changed in the same manner as in the IDT. From FIG. 6A, it can be seen that the resonance frequency f exhibits a downwardly convex quadratic curve tendency with respect to the line occupation ratio mr.

FIG. 6B shows the value of the line occupancy ratio mr that takes the minimum value of the resonance frequency f under the condition of each electrode film thickness H / λ, and the electrode film thickness H / λ is 0.04 ≦ H / λ. When λ ≦ 0.08, it was confirmed that there was a minimum value of the resonance frequency f in the range of the line occupation ratio mr of 0.60 ≦ mr ≦ 0.63. It should be noted that if the line occupancy ratio mr is actually set within the range of 0.55 ≦ mr ≦ 0.68 from the curve of FIG. 6A, the amount of frequency fluctuation can be suppressed, and resonance occurs even if the line occupancy ratio mr varies. Since the frequency f does not vary so much, a SAW device having excellent frequency controllability can be provided.

From the above, the cut angle θ of the rotated Y-cut quartz substrate is −64.0 counterclockwise from the crystal Z axis.
Using a quartz substrate with an angle <θ <−49.3 °, preferably −61.4 ° <θ <−51.1 °, the SAW is propagated in a direction perpendicular to the X axis. SAW constitutes a SAW device which is an SH wave propagating near the substrate surface, and its IDT is made of Al or an alloy mainly containing Al, and the electrode film thickness H / λ normalized by the SAW wavelength is 0.04 < H / λ <0.1
2, preferably 0.05 <H / λ <0.10, or 0.04 ≦ H / λ ≦ 0.08, so that a high Q value and good frequency temperature characteristics can be obtained. mr is 0.53
By setting in the range of ≦ mr ≦ 0.65, the capacity ratio γ can be reduced, and the line occupation ratio mr
It was confirmed that excellent frequency controllability can be obtained by setting the value in the range of 0.55 ≦ mr ≦ 0.68.

Further, the range of line occupancy mr that can reduce the capacity ratio γ is 0.53 ≦ mr ≦ 0.65,
If the line occupancy ratio mr is set to 0.55 ≦ mr ≦ 0.65, a range where the line occupancy ratio mr range 0.55 ≦ mr ≦ 0.68, which provides excellent frequency controllability, is optimal. A SAW device having both the capacity ratio γ and excellent frequency controllability can be realized.

Note that it is difficult to accurately match the line occupancy ratio mr in actually manufacturing a SAW device, and it is considered that a variation of about ± 0.05 may occur when manufacturing errors and measurement errors are taken into consideration. In the SAW device of the present invention, an effect equivalent to that described above can be obtained with such a variation.

So far, only the one-port SAW resonator as shown in FIG. 1 has been mentioned, but the present invention can be applied to other SAW devices. Hereinafter, the structures of various SAW devices will be described.

FIG. 7 shows a 2-port SAW resonator in which IDTs 32 and 33 are arranged on the piezoelectric substrate 31 along the SAW propagation direction, and grating reflectors 34a and 34b are arranged on both sides thereof. Similarly, a high Q value can be realized.

FIG. 8 shows a dual mode SAW (DMS) filter using acoustic coupling of a SAW resonator as one method of the resonator filter. FIG. 8A shows a SAW resonator 4 on a piezoelectric substrate 41.
2 is a laterally coupled DMS filter that is arranged close to and parallel to the propagation direction, and FIG.
This is a 2-port vertically coupled DMS filter in which a SAW resonator made of IDT 52 is arranged on 1 along the SAW propagation direction. The laterally coupled DMS filter uses acoustic coupling in a direction perpendicular to the propagation direction, and the longitudinally coupled DMS filter uses acoustic coupling in the horizontal direction with respect to the propagation direction. These DMS filters are characterized by a flat passband and a good out-of-band suppression. The longitudinally coupled DMS filter may be connected to a SAW resonator in order to make the vicinity of the pass band highly attenuated. In addition, multi-mode SA using higher-order modes
W filter or multiple mode S acoustically coupled both vertically and horizontally to the propagation direction
It can also be applied to AW filters.

FIG. 9 shows another type of resonator filter, a ladder-type SAW filter in which a plurality of 1-port SAW resonators 62 are arranged in series, in parallel, in series and in a ladder form on a piezoelectric substrate 61. Is shown. The ladder-type SAW filter has a filter characteristic having a steep attenuation gradient in the vicinity of the pass band as compared with the DMS filter.

FIG. 10 shows a transversal SAW filter. FIG. 10A shows a transversal SAW filter in which an input IDT 72 and an output IDT 73 are arranged on the piezoelectric substrate 71 along a SAW propagation direction with a predetermined gap. is there. The IDTs 72 and 73 propagate SAW in both directions. In addition, the shield electrode 74 is used to prevent the influence of direct waves between the input and output terminals.
In some cases, a sound absorbing material 75 is applied to both ends of the piezoelectric substrate 71 in order to suppress unnecessary reflected waves from the substrate end surface. The transversal SAW filter can be designed separately for amplitude characteristics and phase characteristics, and is frequently used as an IF filter because of its high out-of-band suppression.

In the transversal SAW filter, since the SAW propagates equally to the left and right along the propagation direction, there is a problem that the insertion loss of the filter increases. As a technique for solving this problem, as shown in FIG. 10B, the so-called single direction in which SAW excitation is made unidirectional by weighting SAW excitation and reflection by changing the electrode finger arrangement and electrode finger width. There is a transversal SAW filter in which single phase unidirectional electrodes (SPUD) 82 and 83 are arranged. Since SAW excitation is unidirectional, low-loss filter characteristics can be obtained. As another structure, there is a so-called reflection bank type transversal SAW filter in which a grating reflector is disposed between the excitation electrodes of the IDT.

In the various SAW devices described above, the cut angle θ of the rotated Y-cut quartz substrate is −64.0 ° <θ <−49.3 °, preferably −61.4 ° <θ <, counterclockwise from the crystal Z axis. -5
Using a quartz substrate of 1.1 °, the SAW propagation direction is perpendicular to the X axis, and the excited SAW constitutes a SAW device that is an SH wave propagating near the substrate surface.
T is made of Al or an alloy mainly containing Al, and the electrode film thickness H / λ normalized by the SAW wavelength.
0.04 <H / λ <0.12, preferably 0.05 <H / λ <0.10, a high Q value and good frequency temperature characteristics can be obtained. mr = 0.5
By setting in the range of 3 ≦ mr ≦ 0.65, the capacity ratio γ can be reduced, and the line occupation ratio m
It is clear that excellent frequency controllability can be obtained by setting r in the range of 0.55 ≦ mr ≦ 0.68.

Further, in the above-described SAW device, a protective film such as SiO ₂ or anodized Al is formed on the IDT or the grating reflector, an adhesion layer or an improvement in power resistance is provided above or below the Al electrode. Even when another metal thin film is formed for the purpose, it is obvious that the same effect as the present invention can be obtained. Needless to say, the SAW device of the present invention can be applied to a sensor device, a module device, an oscillation circuit, and the like. Voltage control SAW
If the SAW device of the present invention is used for an oscillator (VCSO) or the like, the capacitance ratio γ can be reduced, so that the frequency variable width can be increased.

Further, the SAW device of the present invention may have a structure other than the structure in which the SAW chip and the package are wire bonded as shown in FIG. 1, and flip chip bonding (FCB) in which the electrode pad of the SAW chip and the terminal of the package are connected by metal bumps. Structure and S on the wiring board
CSP with flip-chip bonding of AW chip and resin sealing around SAW chip (
Chip Size Package (WCSP) (Wafer Level Chip Size Package) that eliminates the need for a package or wiring board by forming a metal film or resin layer on a SAW chip
It may be a structure or the like. Furthermore, an AQP (All Quartz Package) structure in which a quartz crystal device is sandwiched between quartz or glass substrates and sealed. Since the AQP structure is simply sandwiched between crystal or glass substrates, a package is not required and the thickness can be reduced. If it is sealed with a low melting point glass or directly joined, outgas due to the adhesive is reduced and aging characteristics are achieved. Excellent effect.

It is a figure explaining the SAW resonator which concerns on this invention, (a) is a top view, (b) is sectional drawing of IDT. The comparison between the SAW resonator according to the present invention and the conventional product is shown, in which (a) is a comparison of the Q value and the figure of merit and the secondary temperature coefficient, and (b) is a comparison of the frequency temperature characteristics. The relationship between the electrode film thickness H / λ and the Q value of the SAW resonator according to the present invention is shown in (a), and the relationship between the electrode film thickness H / λ and the secondary temperature coefficient is shown in (b). The relationship between the cut angle θ and the electrode film thickness H / λ when the apex temperature Tp (° C.) of the SAW resonator according to the present invention is Tp = −50, 0, +70, +125 is shown. The relationship between the line occupation ratio mr and the capacity ratio γ when the electrode film thickness H / λ of the SAW resonator according to the present invention is changed is shown in FIG. The minimum value of the line occupation ratio mr is shown in (b). The relationship between the line occupancy ratio mr and the resonance frequency f when the electrode film thickness H / λ of the SAW resonator according to the present invention is changed is shown in FIG. The value of the line occupancy ratio mr taking the minimum value is shown in (b). It is a figure explaining the 2 port SAW resonator which concerns on this invention. It is a figure explaining the DMS filter which concerns on this invention, (a) shows a lateral coupling type DMS filter, (b) shows a vertical coupling type DMS filter. It is a figure explaining the ladder type SAW filter concerning the present invention. It is a figure explaining the transversal SAW filter which concerns on this invention, (a) arrange | positioned transversal SAW filter which arrange | positioned SAW bi-directionally, and (b) arranged IDT which excites SAW in one direction 2 shows a transversal SAW filter. It is a figure explaining the conventional ST cut quartz crystal SAW resonator. It is a figure explaining a -50 degree rotation Y cut 90 degree X propagation quartz substrate. It is a figure explaining the conventional many-pair IDT type SAW resonator. The equivalent circuit diagram of a SAW resonator is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric substrate, 2 ... IDT, 3a, 3b ... Grating reflector, 4a, 4b ... Input / output pad, 5a, 5b ... Metal wire, 6 ... Package, 31 ... Piezoelectric substrate 32, 33 ... ID
T, 34a, 34b grating reflector, 41... Piezoelectric substrate, 42... SAW resonator, 51
... Piezoelectric substrate, 52 ... IDT, 61 ... Piezoelectric substrate, 62 ... 1-port SAW resonator, 71 ... Piezoelectric substrate, 72 ... Input IDT, 73 ... Output IDT, 74 ... Shield electrode, 75 ... Sound absorbing material,
82, 83 ... Unidirectional electrodes.

Claims (10)

A surface acoustic wave device comprising a piezoelectric substrate and an IDT formed on the piezoelectric substrate and made of Al or an alloy containing Al as a main component, wherein the excitation wave is an SH wave,
In the piezoelectric substrate, the cut angle θ is the rotation angle of the crystal Z axis with the crystal X axis as the rotation axis, and the direction of rotation from the crystal + Z axis to the crystal + Y axis side is the rotation direction in which the cut angle θ is negative. , -61.4 ° <θ <set in the range of -51.1 °, and the rotation Y cut quartz substrate composed of quartz flat plate where the surface acoustic wave propagation direction and 90 ° ± 5 ° with respect to the crystal X-axis And
When the wavelength of the surface acoustic wave to be excited is λ, the electrode film thickness H / λ normalized by the wavelength of the IDT is 0.04 <H / λ <0.12,
When the line occupancy ratio mr of electrode fingers constituting the IDT is defined as electrode finger width / (electrode finger width + inter-electrode finger space), the line occupancy ratio mr is set to 0.53 ≦ mr ≦ 0.65. Characteristic surface acoustic wave device (provided that −8.04489 × 10 ⁻⁵ × θ ³ −1.40981 × 10 ⁻² × θ ² −0.825038 × θ−16.0737 <H / λ × mr <− 6.155517 × 10 ⁻⁵ × θ ³ −1.03943 × 10 ⁻² × θ ² −0.586564 × θ-11.0052, and −8.66762 × 10 ⁻⁵ × θ ³ −1. 50414 × 10 ⁻² × θ ² −0.870514 × θ−16.7678 <H / λ × mr <−5.992554 × 10 ⁻⁵ × θ ³ −1.02183 × 10 ⁻² × θ ² −0. And a range satisfying 588704 × θ-11.768) . A surface acoustic wave device comprising a piezoelectric substrate and an IDT formed on the piezoelectric substrate and made of Al or an alloy containing Al as a main component, wherein the excitation wave is an SH wave,
In the piezoelectric substrate, the cut angle θ is the rotation angle of the crystal Z axis with the crystal X axis as the rotation axis, and the direction of rotation from the crystal + Z axis to the crystal + Y axis side is the rotation direction in which the cut angle θ is negative. , -61.4 ° <θ <set in the range of -51.1 °, and the rotation Y cut quartz substrate composed of quartz flat plate where the surface acoustic wave propagation direction and 90 ° ± 5 ° with respect to the crystal X-axis And
When the wavelength of the surface acoustic wave to be excited is λ, the electrode film thickness H / λ normalized by the wavelength of the IDT is 0.04 <H / λ <0.12,
When the line occupancy ratio mr of electrode fingers constituting the IDT is defined as electrode finger width / (electrode finger width + inter-electrode finger space), the line occupancy ratio mr is set to 0.55 ≦ mr ≦ 0.68. Characteristic surface acoustic wave device (provided that −8.04489 × 10 ⁻⁵ × θ ³ −1.40981 × 10 ⁻² × θ ² −0.825038 × θ−16.0737 <H / λ × mr <− 6.155517 × 10 ⁻⁵ × θ ³ −1.03943 × 10 ⁻² × θ ² −0.586564 × θ-11.0052, and −8.66762 × 10 ⁻⁵ × θ ³ −1. 50414 × 10 ⁻² × θ ² −0.870514 × θ−16.7678 <H / λ × mr <−5.992554 × 10 ⁻⁵ × θ ³ −1.02183 × 10 ⁻² × θ ² −0. And a range satisfying 588704 × θ-11.768) . A surface acoustic wave device comprising a piezoelectric substrate and an IDT formed on the piezoelectric substrate and made of Al or an alloy containing Al as a main component, wherein the excitation wave is an SH wave,
In the piezoelectric substrate, the cut angle θ is the rotation angle of the crystal Z axis with the crystal X axis as the rotation axis, and the direction of rotation from the crystal + Z axis to the crystal + Y axis side is the rotation direction in which the cut angle θ is negative. , -61.4 ° <θ <set in the range of -51.1 °, and the rotation Y cut quartz substrate composed of quartz flat plate where the surface acoustic wave propagation direction and 90 ° ± 5 ° with respect to the crystal X-axis And
When the wavelength of the surface acoustic wave to be excited is λ, the electrode film thickness H / λ normalized by the wavelength of the IDT is 0.04 <H / λ <0.12,
When the line occupation ratio mr of the electrode fingers constituting the IDT is defined as electrode finger width / (electrode finger width + inter-electrode finger space), the line occupation ratio mr is set to 0.55 ≦ mr ≦ 0.65. Characteristic surface acoustic wave device (provided that −8.04489 × 10 ⁻⁵ × θ ³ −1.40981 × 10 ⁻² × θ ² −0.825038 × θ−16.0737 <H / λ × mr <− 6.155517 × 10 ⁻⁵ × θ ³ −1.03943 × 10 ⁻² × θ ² −0.586564 × θ-11.0052, and −8.66762 × 10 ⁻⁵ × θ ³ −1. 50414 × 10 ⁻² × θ ² −0.870514 × θ−16.7678 <H / λ × mr <−5.992554 × 10 ⁻⁵ × θ ³ −1.02183 × 10 ⁻² × θ ² −0. And a range satisfying 588704 × θ-11.768) .   4. The surface acoustic wave device according to claim 1, wherein the electrode film thickness H / λ is set in a range of 0.04 <H / λ ≦ 0.08. 5. A surface acoustic wave device comprising a piezoelectric substrate and an IDT formed on the piezoelectric substrate and made of Al or an alloy containing Al as a main component, wherein the excitation wave is an SH wave,
In the piezoelectric substrate, the cut angle θ is the rotation angle of the crystal Z axis with the crystal X axis as the rotation axis, and the direction of rotation from the crystal + Z axis to the crystal + Y axis side is the rotation direction in which the cut angle θ is negative. , -64.0 ° <θ <set in the range of -49.3 °, and the rotation Y cut quartz substrate composed of quartz flat plate where the surface acoustic wave propagation direction and 90 ° ± 5 ° with respect to the crystal X-axis And
When the wavelength of the surface acoustic wave to be excited is λ, the electrode film thickness H / λ normalized by the wavelength of the IDT is 0.05 <H / λ <0.10,
When the line occupancy ratio mr of electrode fingers constituting the IDT is defined as electrode finger width / (electrode finger width + inter-electrode finger space), the line occupancy ratio mr is set to 0.53 ≦ mr ≦ 0.65. Characteristic surface acoustic wave device (provided that −8.04489 × 10 ⁻⁵ × θ ³ −1.40981 × 10 ⁻² × θ ² −0.825038 × θ−16.0737 <H / λ × mr <− 6.155517 × 10 ⁻⁵ × θ ³ −1.03943 × 10 ⁻² × θ ² −0.586564 × θ-11.0052, and −8.66762 × 10 ⁻⁵ × θ ³ −1. 50414 × 10 ⁻² × θ ² −0.870514 × θ−16.7678 <H / λ × mr <−5.992554 × 10 ⁻⁵ × θ ³ −1.02183 × 10 ⁻² × θ ² −0. And a range satisfying 588704 × θ-11.768) . A surface acoustic wave device comprising a piezoelectric substrate and an IDT formed on the piezoelectric substrate and made of Al or an alloy containing Al as a main component, wherein the excitation wave is an SH wave,
In the piezoelectric substrate, the cut angle θ is the rotation angle of the crystal Z axis with the crystal X axis as the rotation axis, and the direction of rotation from the crystal + Z axis to the crystal + Y axis side is the rotation direction in which the cut angle θ is negative. , -64.0 ° <θ <set in the range of -49.3 °, and the rotation Y cut quartz substrate composed of quartz flat plate where the surface acoustic wave propagation direction and 90 ° ± 5 ° with respect to the crystal X-axis And
When the wavelength of the surface acoustic wave to be excited is λ, the electrode film thickness H / λ normalized by the wavelength of the IDT is 0.05 <H / λ <0.10,
When the line occupancy ratio mr of electrode fingers constituting the IDT is defined as electrode finger width / (electrode finger width + inter-electrode finger space), the line occupancy ratio mr is set to 0.55 ≦ mr ≦ 0.68. Characteristic surface acoustic wave device (provided that −8.04489 × 10 ⁻⁵ × θ ³ −1.40981 × 10 ⁻² × θ ² −0.825038 × θ−16.0737 <H / λ × mr <− 6.155517 × 10 ⁻⁵ × θ ³ −1.03943 × 10 ⁻² × θ ² −0.586564 × θ-11.0052, and −8.66762 × 10 ⁻⁵ × θ ³ −1. 50414 × 10 ⁻² × θ ² −0.870514 × θ−16.7678 <H / λ × mr <−5.992554 × 10 ⁻⁵ × θ ³ −1.02183 × 10 ⁻² × θ ² −0. And a range satisfying 588704 × θ-11.768) . A surface acoustic wave device comprising a piezoelectric substrate and an IDT formed on the piezoelectric substrate and made of Al or an alloy containing Al as a main component, wherein the excitation wave is an SH wave,
In the piezoelectric substrate, the cut angle θ is the rotation angle of the crystal Z axis with the crystal X axis as the rotation axis, and the direction of rotation from the crystal + Z axis to the crystal + Y axis side is the rotation direction in which the cut angle θ is negative. , -64.0 ° <θ <set in the range of -49.3 °, and the rotation Y cut quartz substrate composed of quartz flat plate where the surface acoustic wave propagation direction and 90 ° ± 5 ° with respect to the crystal X-axis And
When the wavelength of the surface acoustic wave to be excited is λ, the electrode film thickness H / λ normalized by the wavelength of the IDT is 0.05 <H / λ <0.10,
When the line occupation ratio mr of the electrode fingers constituting the IDT is defined as electrode finger width / (electrode finger width + inter-electrode finger space), the line occupation ratio mr is set to 0.55 ≦ mr ≦ 0.65. Characteristic surface acoustic wave device (provided that −8.04489 × 10 ⁻⁵ × θ ³ −1.40981 × 10 ⁻² × θ ² −0.825038 × θ−16.0737 <H / λ × mr <− 6.155517 × 10 ⁻⁵ × θ ³ −1.03943 × 10 ⁻² × θ ² −0.586564 × θ-11.0052, and −8.66762 × 10 ⁻⁵ × θ ³ −1. 50414 × 10 ⁻² × θ ² −0.870514 × θ−16.7678 <H / λ × mr <−5.992554 × 10 ⁻⁵ × θ ³ −1.02183 × 10 ⁻² × θ ² −0. And a range satisfying 588704 × θ-11.768) .   8. The surface acoustic wave device according to claim 5, wherein the electrode film thickness H / λ is set in a range of 0.05 <H / λ ≦ 0.08. 9.   A module apparatus using the surface acoustic wave device according to claim 1.   An oscillation circuit comprising the surface acoustic wave device according to claim 1.

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