KR100839789B1 - Surface acoustic wave device - Google Patents

Abstract

It is an object of the present invention to provide a surface acoustic wave device in which an insulator layer is formed so as to cover an IDT electrode, and the surface of the insulator layer is flattened, and the reflection coefficient of the electrode can be sufficiently large. .

According to the structure of the surface acoustic wave device of the present invention, a plurality of grooves 1b are formed on the upper surface of the piezoelectric plate 1, and the electrode film 3 constituting the IDT electrode is filled with electrode material in these grooves 1b. ) Is formed, and an insulating layer 4 such as a SiO ₂ film is formed to cover the electrode film 3 formed in the piezoelectric plate 1 and the groove 1b, and the surface of the insulating layer 4 is flat. It is supposed to be done.

Surface acoustic wave device, IDT electrode, groove, insulation layer, piezoelectric plate, electrode film

Description

Surface acoustic wave device {SURFACE ACOUSTIC WAVE DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface acoustic wave device used for a resonator, a band pass filter, and the like, and a method of manufacturing the same. More particularly, the surface acoustic wave device having a structure in which an insulator layer is formed to cover an IDT electrode and a manufacturing method thereof It is about a method.

In a duplexer (DPX) and an RF filter used in a mobile communication system, both broadband and good temperature characteristics are required to be satisfied. Conventionally, the DPX and is used for RF filters on surface acoustic wave device, a piezoelectric substrate is used consisting of 36 ° ~50 ° rotation Y plate X-propagation LiTaO _3. This piezoelectric plate had a frequency temperature coefficient of about -45 to -35 ppm / 占 폚. In order to improve the temperature characteristic, a method of forming a SiO ₂ film having a positive frequency temperature coefficient is known so as to cover an IDT electrode on a piezoelectric plate.

However, in the structure in which the SiO ₂ film was formed to cover the IDT electrode, a step was generated in the portion where the electrode-fingers of the IDT electrode existed and the portion where the electrode-fingers did not exist. In other words, the height of the surface of the SiO ₂ film was inevitably different between the portion where the IDT electrode was present and the portion where the IDT electrode was not present. Therefore, there is a problem that insertion loss deteriorates due to irregularities on the surface of the SiO ₂ film.

In addition, as the film thickness of the IDT electrode increases, the unevenness is inevitably increased. Therefore, the film thickness of IDT electrode could not be thickened.

As a solution to this problem, Patent Document 1 below forms a SiO ₂ film so as to cover the IDT electrode and the first insulator layer after forming the first insulator layer having the same thickness as the electrode between the electrode fingers of the IDT electrode. A method is disclosed. Here, since the base of the SiO ₂ film becomes flat, the surface of the SiO ₂ film is flattened. In the surface acoustic wave device described in Patent Literature 1, the IDT electrode is composed of a metal having a higher density than Al, an alloy containing the metal as a main component, a metal having a higher density than Al, or an alloy containing the metal as a main component and another metal. It is comprised by the laminated film, and the density of an electrode is 1.5 times or more of the 1st insulator layer.

On the other hand, Patent Literature 2 below discloses a surface acoustic wave device in which an IDT electrode is formed by forming a groove in one surface of a LiTaO ₃ substrate or a LiNbO ₃ substrate and filling Al into the groove.

Patent Document 1: Japanese Patent Application Laid-Open No. 2004-112748

Patent Document 2: Japanese Patent Application Laid-Open No. 9-83030

However, in the surface acoustic wave device described in Patent Literature 1, since an electrode heavier than Al is used, the reflection coefficient of the electrode is large when the sound velocity and frequency deviation are large with respect to the variation in the electrode thickness, and the electrode made of Al is actually formed. Is considerably low, indicating that sufficient characteristics cannot be obtained as a surface acoustic wave resonator or surface acoustic wave filter.

In the surface acoustic wave device described in Patent Document 2, an electrode is formed by filling Al into a groove formed in a LiTaO ₃ substrate or a LiNbO ₃ substrate. Therefore, the surface of the material layer in which the material layer is laminated to cover the electrode can be flattened. However, when the surface acoustic wave resonator constituted the surface acoustic wave filter, sufficient characteristics still could not be obtained.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art, wherein an insulator layer made of SiO ₂ or the like is formed to cover the IDT electrode, and the surface of the SiO ₂ film is flattened, whereby the insertion loss is sufficiently small. In addition, even when the electrode is formed of Al or the like, the reflection coefficient is sufficiently large, and therefore, a surface acoustic wave device capable of obtaining good resonance characteristics, filter characteristics, and the like is provided.

According to one broad aspect of the first invention, a plurality of grooves are formed on a LiTaO ₃ substrate having an upper surface, an IDT electrode formed by filling Al into the grooves, and a SiO ₂ formed to cover the LiTaO ₃ substrate and the IDT electrode. A layer, the upper surface of the SiO ₂ layer is flat, the wavelength of the surface acoustic wave is λ, and the Euler angle of the LiTaO ₃ substrate is in one of the ranges shown in Table 1 below. The film thickness of is in the range where the Euler angle of the LiTaO ₃ substrate and the Euler angle shown in Table 1 correspond to the position, and the thickness of the SiO ₂ layer corresponds to the film thickness of the IDT electrode and the Al thickness shown in Table 1 A surface acoustic wave device is provided, which is in a range shown at a position.

In addition, in the following notation, H represents a film thickness. The normalized film thickness is a value obtained by dividing the film thickness H by the surface wave wavelength λ.

α = 0.05 or less θ of Euler angles (0, θ, 0) 0.125≤SiO ₂ layer thickness≤0.2 0.02≤Al thickness <0.04 (0, 114 ° to 142 °, 0) 0.04≤Al thickness <0.06 (0, 115 ° to 143 °, 0) 0.06≤Al thickness <0.1 (0, 113 ° to 145 °, 0) 0.1≤Al thickness≤0.14 (0, 112 ° to 146 °, 0) 0.2 <SiO ₂ layer thickness≤0.275 0.02≤Al thickness <0.04 (0, 113 ° to 140 °, 0) 0.04≤Al thickness <0.06 (0, 113 ° to 140 °, 0) 0.06≤Al thickness <0.1 (0, 111 ° to 140 °, 0) 0.1≤Al thickness≤0.14 (0, 111 ° to 140 °, 0) 0.275 <SiO ₂ layer thickness≤0.35 0.02≤Al thickness <0.04 (0, 111 ° to 137 °, 0) 0.04≤Al thickness <0.06 (0, 111 ° to 137 °, 0) 0.06≤Al thickness <0.1 (0, 109 ° to 136 °, 0) 0.1≤Al thickness≤0.14 (0, 107 ° to 136 °, 0)

Both SiO ₂ layer thickness and Al thickness are standardized film thickness H / λ

In one specific aspect of the surface acoustic wave device according to the first invention, the Euler angle of the LiTaO ₃ substrate is in any one of the ranges shown in Table 2 below, and the film thickness of the IDT electrode is the Euler of the LiTaO ₃ substrate. angle in the range shown in the Euler angle corresponding to a position shown in Table 2, the thickness of the SiO ₂ layer is in a range shown in a position at which the Al thickness according to the thickness shown in Table 2 of the IDT electrode response.

θ of Euler angle (0, θ, 0) of α = 0.025 or less 0.125≤SiO ₂ layer thickness≤0.2 0.02≤Al thickness <0.04 (0, 118 ° to 137 °, 0) 0.04≤Al thickness <0.06 (0, 117 ° to 139 °, 0) 0.06≤Al thickness <0.1 (0, 117 ° to 141 °, 0) 0.1≤Al thickness≤0.14 (0, 116 ° to 141 °, 0) 0.2 <SiO ₂ layer thickness≤0.275 0.02≤Al thickness <0.04 (0, 115 ° to 137 °, 0) 0.04≤Al thickness <0.06 (0, 115 ° to 138 °, 0) 0.06≤Al thickness <0.1 (0, 115 ° to 138 °, 0) 0.1≤Al thickness≤0.14 (0, 114 ° to 136 °, 0) 0.275 <SiO ₂ layer thickness≤0.35 0.02≤Al thickness <0.04 (0, 113 ° to 137 °, 0) 0.04≤Al thickness <0.06 (0, 113 ° to 137 °, 0) 0.06≤Al thickness <0.1 (0, 111 ° to 136 °, 0) 0.1≤Al thickness≤0.14 (0, 112 ° to 133 °, 0)

Both SiO ₂ layer thickness and Al thickness are standardized film thickness H / λ

According to another broad aspect of the surface acoustic wave device according to the second aspect of the present invention, there is provided a LiTaO ₃ substrate having a plurality of grooves formed on an upper surface thereof, an IDT electrode formed by filling Al into the grooves, and the LiTaO ₃ substrate and IDT electrode. An SiO ₂ layer formed so as to cover the upper surface of the SiO ₂ layer, wherein the wavelength of the surface acoustic wave is?, And the Euler angle of the LiTaO ₃ substrate is in any one of the ranges shown in Table 3 below. The film thickness of the IDT electrode is in a range where the Euler angles of the LiTaO ₃ substrate and the Euler angles described in Table 3 are shown in corresponding positions, and the thickness of the SiO ₂ layer is set to the film thickness of the IDT electrode and Table 3 A surface acoustic wave device is provided, wherein the Al thickness described in the above is in a range shown at a corresponding position.

α = 0.05 or less θ of Euler angles (0, θ, 0) 0.125≤SiO ₂ layer thickness≤0.20 0.02≤Al thickness <0.04 (0, 119 ° to 152 °, 0) 0.04≤Al thickness <0.06 (0, 120 ° to 153 °, 0) 0.06≤Al thickness <0.1 (0, 124 ° to 158 °, 0) 0.1≤Al thickness≤0.14 (0, 128 ° to 155 °, 0) 0.20 <SiO ₂ layer thickness≤0.275 0.02≤Al thickness <0.04 (0, 123 ° to 152 °, 0) 0.04≤Al thickness <0.06 (0, 124.5 ° to 153 °, 0) 0.06≤Al thickness <0.1 (0, 123.5 ° to 154 °, 0) 0.1≤Al thickness≤0.14 (0, 119 ° to 157 °, 0) 0.275 <SiO ₂ layer thickness≤0.35 0.02≤Al thickness <0.04 (0, 124 ° to 150 °, 0) 0.04≤Al thickness <0.06 (0, 124 ° to 146 °, 0) 0.06≤Al thickness <0.1 (0, 114 ° to 149 °, 0) 0.1≤Al thickness≤0.14 (0, 103 ° to 148 °, 0)

Both SiO ₂ layer thickness and Al thickness are standardized film thickness H / λ

In one specific aspect of the second invention, the Euler angle of the LiTaO ₃ substrate is in any of the ranges shown in Table 4 below, and the film thickness of the IDT electrode is in the Euler angle of the LiTaO ₃ substrate and in Table 4 above. The Euler angle described is in the range indicated at the corresponding position, and the thickness of the SiO ₂ layer is in the range indicated at the position where the film thickness of the IDT electrode and the Al thickness described in Table 4 correspond.

θ of Euler angle (0, θ, 0) of α = 0.025 or less 0.125≤SiO ₂ layer thickness≤0.20 0.02≤Al thickness <0.04 (0, 123 ° to 148 °, 0) 0.04≤Al thickness <0.06 (0, 127 ° to 149 °, 0) 0.06≤Al thickness <0.1 (0, 127.5 ° to 154 °, 0) 0.1≤Al thickness≤0.14 (0, 131 ° to 158 °, 0) 0.20 <SiO ₂ layer thickness≤0.275 0.02≤Al thickness <0.04 (0, 127 ° to 148 °, 0) 0.04≤Al thickness <0.06 (0, 128 ° to 149 °, 0) 0.06≤Al thickness <0.1 (0, 128 ° to 149 °, 0) 0.1≤Al thickness≤0.14 (0, 124 ° to 155 °, 0) 0.275 <SiO ₂ layer thickness≤0.35 0.02≤Al thickness <0.04 (0, 128 ° to 146 °, 0) 0.04≤Al thickness <0.06 (0, 128 ° to 146 °, 0) 0.06≤Al thickness <0.1 (0, 119 ° to 146 °, 0) 0.1≤Al thickness≤0.14 (0, 110 ° to 145 °, 0)

Both SiO ₂ layer thickness and Al thickness are standardized film thickness H / λ

In another specific aspect of the surface acoustic wave device according to the first invention, the Euler angles of the LiTaO ₃ substrate satisfy the Euler angles shown in Table 1 and Table 3 above in common.

More preferably, the Euler angles satisfy the Euler angles shown in Tables 1 and 4 described above in common.

In another specific aspect of the first invention, the Euler angles of the LiTaO ₃ substrate satisfy the Euler angles shown in Tables 2 and 3 above, and more preferably, the Euler angles shown in Tables 2 and 4 Satisfy in common.

In another specific aspect of the surface acoustic wave device according to the present invention, the upper surface of the IDT electrode and the upper surface of the LiTaO ₃ substrate are coplanar.

In another specific aspect of the surface acoustic wave device according to the present invention, the groove is surrounded by an inner bottom surface, a pair of inner surfaces connecting the inner bottom surface and the upper surface of the LiTaO ₃ substrate, and the inner surface. And the inner angle of the groove formed by the upper surface of the piezoelectric plate are in the range of 45 ° to 90 °.

According to another broad aspect of the surface acoustic wave device according to the third aspect of the present invention, there is provided a LiNbO ₃ substrate having a plurality of grooves formed on an upper surface thereof, an IDT electrode formed by filling Al with the grooves, the LiNbO ₃ substrate, and an IDT electrode. A SiO ₂ layer formed so as to cover, the top surface of the SiO ₂ layer is flat, the wavelength of the surface acoustic wave is?, And the standardized film thickness of the IDT electrode is 0.04 to 0.16, and the SiO ₂ layer is standardized. The film thickness is 0.2 to 0.4, and the surface acoustic wave device is provided, wherein the Euler angle of the LiNbO ₃ substrate is in any one of the ranges shown in Table 5 below.

Θ of Euler angles (0 °, θ, 0 °) (0 °, 85 ° to 120 °, 0 °) (0 °, 125 ° to 141 °, 0 °) (0 °, 145 ° to 164 °, 0 °) (0 °, 160 ° ~ 180 °, 0 °)

In one specific aspect of the third invention, the Euler angle of the LiNbO ₃ substrate is in one of the ranges shown in Table 6 below.

Θ of Euler angles (0 °, θ, 0 °) (0 °, 90 ° to 110 °, 0 °) (0 °, 125 ° to 136 °, 0 °) (0 °, 149 ° to 159 °, 0 °) (0 °, 165 ° to 175 °, 0 °)

In another specific aspect of the third invention, the standardized film thickness of the IDT electrode is 0.06 to 0.12.

In another specific aspect of the third invention, the normalized film thickness of the SiO ₂ layer is 0.25 to 0.3.

In still another specific aspect of the third invention, the upper surface of the IDT electrode and the upper surface of the LiNbO ₃ substrate are coplanar.

In another specific aspect of the third invention, the groove is surrounded by an inner bottom surface and a pair of inner surfaces connecting the inner bottom surface and the upper surface of the LiNbO ₃ substrate, and the inner surface and the upper surface of the piezoelectric plate are The inner angle of the groove is in the range of 45 ° to 90 °.

The inside angle of the groove is preferably in the range of 50 ° to 80 °.

In another specific aspect of the surface acoustic wave device according to the present invention, in addition to the electrode layer made of Al, the IDT electrode is made of a metal or alloy having a higher density than Al, and further includes an adhesion layer laminated on the electrode layer made of Al. Equipped.

In another specific aspect of the surface acoustic wave device according to the present invention, the IDT electrode further comprises an adhesion layer made of a metal having a higher density than Al and laminated on an electrode layer made of Al.

In the surface acoustic wave device according to the first aspect of the invention, a plurality of grooves are formed on the upper surface of the LiTaO ₃ substrate, and Al is filled in the grooves to form an IDT electrode. Therefore, in the SiO ₂ layer formed to cover the LiTaO ₃ substrate and the IDT electrode, since the IDT electrode is formed by Al filling in the groove, the top surface of the SiO ₂ layer is flattened. Therefore, deterioration of insertion loss is unlikely to occur. In addition, as apparent from the specific experimental example described later, since Al is filled in the groove to form the electrode, the reflection coefficient of the IDT electrode is sufficiently large. Therefore, good resonance characteristics and filter characteristics can be obtained.

In addition, while the frequency temperature coefficient of the LiTaO ₃ substrate is negative, the frequency temperature coefficient of the SiO ₂ layer is positive. Accordingly, it is possible to provide a surface acoustic wave device having good frequency temperature characteristics in which the frequency temperature coefficient is close to zero as a whole.

Further, the Euler angle of the LiTaO ₃ substrate is in any of the ranges shown in Table 1 above, and the thickness of Al and the thickness of the SiO ₂ layer constituting the IDT electrode are described in the Euler angle range shown in Table 1 Since it is in the specific range which exists, it becomes possible to raise a resonance characteristic and a filter characteristic further.

In particular, when the Euler angle of a LiTaO ₃ substrate is in the range shown in Table 2, and the Al thickness of the IDT electrode and the thickness of the SiO ₂ layer are in a specific range corresponding to the Euler angle range as shown in Table 2 In the above, the layer resonance characteristic and the filter characteristic can be further improved.

Also in the second invention of the present application, a plurality of grooves are formed on the upper surface of the LiTaO ₃ substrate, and since the IDT electrode is formed by filling Al in the grooves, it is possible to flatten the upper surface of the SiO ₂ layer. . Therefore, deterioration of insertion loss is unlikely to occur.

In addition, as apparent from the experimental example described later, since Al is filled in the groove to form the electrode, the reflection coefficient of the IDT electrode is sufficiently large. In addition, the one range in which the Euler angles of the LiTaO ₃ substrate shown in Table 3, since the thickness and, SiO thickness of the _second layer of Al which constitute the IDT electrode is in a specific range as shown in Table 3, resonance It is possible to further improve characteristics and filter characteristics. In particular, when the Euler angle is any of the ranges shown in Table 4, and the thickness of Al and the thickness of SiO ₂ are in the specific ranges shown in Table 4, the layer resonance characteristics and the filter characteristics can be further improved. .

In the first invention, when the Euler angle of the LiTaO ₃ substrate is not only in one of the ranges shown in Table 1, but also in any of the Euler angle ranges shown in Table 3, the resonance characteristics and the filter are satisfied. The characteristic can be further improved.

More preferably, when not only one Euler angle range shown in Table 1 is satisfied but also any Euler angle range shown in Table 4, a resonance characteristic and a filter characteristic can be improved further. have.

In the first invention, when the Euler angle range satisfies any one of the ranges shown in Table 2 and also satisfies any Euler angle range shown in Table 3, the resonance characteristics and the filter characteristics are changed. Further improvement can be achieved, and in particular, when the Euler angle ranges shown in Table 2 and Table 4 are satisfied in common, the layer filter characteristics and the resonance characteristics can be further improved.

In the case where the IDT electrode has an adhesion layer made of a metal or alloy having a higher density than Al in addition to the electrode layer made of Al, the bonding strength between the IDT electrode and the LiTaO ₃ substrate or the LiNbO ₃ substrate is increased, and the resistance against stress migration and the like is increased. Power can be improved. Therefore, it becomes possible to improve the electric power resistance of the surface acoustic wave device.

On the other hand, metals having a higher density than Al include Ti, Cu, W, Cr, Ni, and the like, and alloys having higher density than Al include alloys of Al such as AlCu and metals having higher density than Al, or NiCr. As described above, an alloy mainly composed of a plurality of metals having a higher density than Al and the like can be given.

In particular, since the LiTaO ₃ substrate is an Euler angle LiTaO ₃ substrate in any one of the ranges shown in Table 1, not only is the temperature characteristic good but the attenuation constant α is reduced to 0.05 (dB / λ) or less. Therefore, a better resonance characteristic or filter characteristic can be obtained. More preferably, when the Euler angle is in any of the ranges in Table 2, the attenuation constant α becomes 0.025 (dB / λ) or less, more preferably.

When the LiTaO ₃ substrate is an Euler angle LiTaO ₃ substrate in any of the ranges shown in Table 3, the attenuation constant α is 0.05 (dB / λ) or less, and more preferably in any one of Table 4 In the range, the attenuation constant α is 0.025 (dB / λ) or less. Therefore, not only good temperature characteristics and sufficient reflection coefficients are obtained, but also the damping constant is sufficiently small, so that even better resonance characteristics or filter characteristics can be obtained.

Moreover, when the thickness of Al or Al alloy which comprises the said IDT electrode is set to the film thickness corresponding to the Euler angle shown in the said Table 1-Table 4, the temperature characteristic becomes a more favorable resonance characteristic by this, or Filter characteristics can be obtained.

In the surface acoustic wave device according to the third invention, a LiNbO ₃ substrate is used, and a plurality of grooves are formed on the upper surface of the LiNbO ₃ substrate. Al is filled in these grooves to form an IDT electrode. Further, the SiO ₂ layer is formed so as to cover the LiNbO ₃ substrate and the IDT electrode, and the top surface of the SiO ₂ layer is flat. Therefore, deterioration of insertion loss is unlikely to occur.

In addition, since Al is charged and the electrode is formed, the reflection coefficient of the IDT electrode is sufficiently large. Therefore, good resonance characteristics and filter characteristics can be obtained.

In addition, while the frequency temperature coefficient of the LiNbO ₃ substrate is negative, the frequency temperature coefficient of the SiO ₂ layer is positive. Accordingly, it is possible to provide a surface acoustic wave device having good frequency temperature characteristics.

Further, since the Euler angle of the LiNbO ₃ substrate is in any of the ranges shown in Table 5, the resonance characteristic and the filter characteristic can be further improved.

In particular, when the Euler angle of the LiNbO ₃ substrate is in the range shown in Table 6, and the Al thickness of the IDT electrode and the thickness of the SiO ₂ layer are in the specific range corresponding to the Euler angle range as shown in Table 6, Therefore, the resonance characteristics and the filter characteristics can be further improved.

In the third invention, when the standardized film thickness of the IDT electrode is in the range of 0.06 to 0.12, the frequency temperature characteristic can be further improved.

In the third invention, in the case where the standardized film thickness of the SiO ₂ layer is in the range of 0.25 to 0.3, the frequency temperature characteristic can be further improved in the same manner.

In the present invention, when the upper surface of the electrode and the upper surface of the piezoelectric plate are coplanar, the surface of the insulator layer can be reliably flattened even if the insulator layer is formed by a conventional film forming method. Can be. In addition, in this invention, the upper surface of an electrode and the upper surface of a piezoelectric plate do not necessarily need to be coplanar. The upper surface of the electrode may slightly protrude upward from the upper surface of the piezoelectric plate, or may be slightly retracted from the upper surface of the piezoelectric plate.

In the present invention, when the inside angle of the groove is in the range of 45 ° to 90 °, more preferably in the range of 50 ° to 80 °, the groove angle is not affected by any variation in the inside angle of the groove. Due to the small change in the electromechanical coupling coefficient, variations in the characteristics of the surface acoustic wave device can be reduced. That is, even if the groove angle of the groove is slightly changed at the time of manufacture, the surface acoustic wave device having stable characteristics can be provided.

1A to 1F are front sectional views for explaining the method for manufacturing a surface acoustic wave device according to the first embodiment of the present invention.

FIG. 2 is a schematic plan view showing the electrode structure of a surface acoustic wave resonator as a surface acoustic wave device obtained in the embodiment shown in FIG.

3 is a diagram showing a change in the electromechanical coupling coefficient when the electrode film thickness is changed in the surface acoustic wave resonators of Example and Comparative Example 1. FIG.

FIG. 4 is a diagram showing a change in the reflection coefficient when the electrode film thickness is changed in the surface acoustic wave resonators of Examples and the surface acoustic wave resonators of Comparative Examples 1 and 2. FIG.

5A to 5D are schematic front sectional views for explaining the second example of the method for manufacturing the surface acoustic wave device of the present invention.

6 is a normalized film thickness of an electrode made of Al and a normalized film of an SiO ₂ layer using a LiTaO ₃ substrate of (0 °, 126 °, 0 °) in the surface acoustic wave resonators of Example and Comparative Example 1; It is a figure which shows the change of the reflection coefficient in the case of changing thickness.

7 is a normalized film thickness of an electrode made of Al and a normalized film of an SiO ₂ layer using a LiTaO ₃ substrate of (0 °, 126 °, 0 °) in the surface acoustic wave resonators of Examples and Comparative Examples 1 It is a figure which shows the change of the electromechanical coupling coefficient in the case of changing thickness.

Fig. 8 shows the surface acoustic wave device of the embodiment in which the Euler angle of the LiTaO ₃ substrate is varied, the standardized film thickness of the electrode made of Al is 0.06, and the standardized film thickness of the SiO ₂ layer is variously changed. It is a figure which shows the change of the frequency temperature coefficient TCF in the case.

Fig. 9 shows the surface acoustic wave device according to the embodiment, in which the Euler angle of the LiTaO ₃ substrate is varied, the standardized film thickness of the electrode made of Al is 0.08, and the standardized film thickness of the SiO ₂ layer is variously changed. It is a figure which shows the change of the frequency temperature coefficient TCF in the case.

Fig. 10 shows the surface acoustic wave device of the embodiment in which the Euler angle of the LiTaO ₃ substrate is varied, the standardized film thickness of the electrode made of Al is 0.1, and the standardized film thickness of the SiO ₂ layer is variously changed. It is a figure which shows the change of the frequency temperature coefficient TCF in the case.

Fig. 11 shows the resonant frequency when the standardized film thickness of the SiO ₂ film is 0.15 in the surface acoustic wave device of the embodiment, and the standardized film thickness of the electrode composed of Al and θ of the Euler angle of the LiTaO ₃ substrate is varied. It is a figure which shows the change of the damping constant in the side.

In the Figure 12 embodiment, the surface acoustic wave device, SiO ₂ film, the resonant frequency of the case and of the Euler angle θ of normalized to 0.25, and LiTaO ₃ substrate to the film thickness, which changes in the normalized film thickness of electrode made of Al by a number of It is a figure which shows the change of the damping constant in the side.

Fig. 13 shows a resonant frequency when the standardized film thickness of an SiO ₂ film is 0.35 in the surface acoustic wave device of the embodiment, and the standardized film thickness of an electrode composed of Al and the Euler angle of the LiTaO ₃ substrate is varied. It is a figure which shows the change of the damping constant in the side.

Fig. 14 shows the anti-resonance when the standardized film thickness of the SiO ₂ film is 0.15 in the surface acoustic wave device of the embodiment, and the standardized film thickness of the electrode composed of Al and θ of the Euler angle of the LiTaO ₃ substrate is varied. It is a figure which shows the change of the attenuation constant in the frequency side.

Figure 15 is an embodiment the elastic at the surface wave device, SiO ₂ film and the Euler angle θ of normalized to 0.25, and LiTaO ₃ substrate to the film thickness, anticommunist cases for changing the normalized film thickness of electrode made of Al by a number of binary It is a figure which shows the change of the attenuation constant in the frequency side.

Fig. 16 shows the anti-resonance when the standardized film thickness of the SiO ₂ film is 0.35 in the surface acoustic wave device of the example, and the standardized film thickness of the electrode composed of Al and the Euler angle of the LiTaO ₃ substrate is varied. It is a figure which shows the change of the attenuation constant in the frequency side.

17A and 17B are cross-sectional views each partially showing the structure of an IDT electrode formed in a multilayer structure between an electrode layer containing Al as a main component and an electrode layer having higher electric power resistance than Al.

Fig. 18 is a schematic plan view showing the electrode structure of a two-port surface acoustic wave resonator as another embodiment of the present invention.

19 is a schematic plan view showing an electrode structure of a ladder filter as another example of the electrode structure of the surface acoustic wave device to which the present invention is applied.

20 is a schematic plan view showing an electrode structure of a lattice type surface acoustic wave filter as still another example of the electrode structure of the surface acoustic wave device to which the present invention is applied.

Fig. 21 is a schematic front sectional view for explaining the cabinet angle of the groove in the surface acoustic wave device of the present invention.

Fig. 22 shows electromechanical coupling normalized to the electromechanical coupling coefficient when the internal angle X of the groove is 90 ° when the standardized film thickness of the electrode made of Al constituting the IDT electrode is changed. It is a figure which shows a change of a coefficient.

Fig. 23 shows that the thickness of SiO ₂ is 0.20 lambda, and the inside angle X of the groove when the normalized film thickness of the electrode made of Al constituting the IDC electrode and the cabinet of the groove of the surface acoustic wave device is changed to 90 °. A diagram showing a change in the electromechanical coupling coefficient normalized to the electromechanical coupling coefficient of.

Fig. 24 is an electric machine when the internal angle X of the groove is 90 ° when θ = 120 ° and the standardized film thickness of the electrode made of Al constituting the IDT electrode and the inner corner of the groove of the surface acoustic wave device. It is a figure which shows the change of the electromechanical coupling coefficient normalized by the coupling coefficient.

Fig. 25 shows the normalized film thickness of an electrode made of Al of 0.08, and is normalized to an electromechanical coupling coefficient when the internal angle X of the groove is 90 ° when the internal angle of the groove of the surface acoustic wave device and the Euler angle of LiTaO ₃ are changed. It is a figure which shows the change of the electromechanical coupling coefficient.

Fig. 26 shows SiO in the surface acoustic wave device according to the embodiment in which the Euler angles of the LiNbO ₃ substrate were (0 °, 170 °, 0 °), and the electrode normalized film thicknesses made of Al were 0.02, 0.06, 0.1, 0.16. _It is a figure which shows the change of TCF when the normalized film thickness of ₂ is changed.

Fig. 27 shows the Euler angle of the LiNbO ₃ substrate as (0 °, 105 °, 0 °) in the surface acoustic wave device of the example, and the standard film thickness of SiO ₂ is made of Al for the case of 0.2, 0.3, and 0.4. and changes in electromechanical coefficient K ² of when the electrode normalized film thickness is changed, a view given the change in electromechanical coupling coefficient K ² of the copper (同) condition of a conventional surface acoustic wave device.

FIG. 28 shows that the Euler angle of the LiNbO ₃ substrate is (0 °, 105 °, 0 °) in the surface acoustic wave device of the embodiment, and Al is made of SiO _{2 for} the standardized film thicknesses of 0.2, 0.3, and 0.4. It is a figure which shows the change of the reflection coefficient at the time of changing the electrode normalized film thickness, and the change of the reflection coefficient in the same conditions of the conventional surface acoustic wave device.

FIG. 29 shows that the Euler angle of the LiNbO ₃ substrate is (0 °, 131 °, 0 °) in the surface acoustic wave device of the embodiment, and Al is made of 0.2, 0.3, and 0.4 for the normalized film thickness of SiO ₂ . changes in the electromechanical coupling factor K ² when the electrode normalized film thickness is changed with a view given the change in electromechanical coupling coefficient K ² in the same conditions of the conventional surface acoustic wave device.

FIG. 30 shows that the Euler angle of the LiNbO ₃ substrate is (0 °, 131 °, 0 °) in the surface acoustic wave device of the embodiment, and Al is made of SiO _{2 for} the standardized film thicknesses of 0.2, 0.3, and 0.4. It is a figure which shows the change of the reflection coefficient at the time of changing the electrode normalized film thickness, and the change of the reflection coefficient in the same conditions of the conventional surface acoustic wave device.

31 shows that the Euler angle of the LiNbO ₃ substrate is (0 °, 154 °, 0 °) in the surface acoustic wave device of the embodiment, and Al is made of SiO _{2 for} the standardized film thicknesses of 0.2, 0.3, and 0.4. changes in the electromechanical coupling factor K ² when the electrode normalized film thickness is changed with a view given the change in electromechanical coupling coefficient K ² in the same conditions of the conventional surface acoustic wave device.

32 is for the case of the embodiment of the Euler angles of the LiNbO ₃ substrate in the surface acoustic wave device (0 °, 154 °, 0 °) to a, the normalized film thickness of the SiO ₂ 0.2, 0.3, 0.4, consisting of Al It is a figure which shows the change of the reflection coefficient at the time of changing the electrode normalized film thickness, and the change of the reflection coefficient in the same conditions of the conventional surface acoustic wave device.

Fig. 33 shows the Euler angles of the LiNbO ₃ substrates (0 °, 170 °, 0 °) in the surface acoustic wave device of the example, and the standardized film thicknesses of SiO ₂ are made of Al in the case of 0.2, 0.3, and 0.4. changes in the electromechanical coupling factor K ² when the electrode normalized film thickness is changed with a view given the change in electromechanical coupling coefficient K ² in the same conditions of the conventional surface acoustic wave device.

Fig. 34 shows that the Euler angle of the LiNbO ₃ substrate is (0 °, 170 °, 0 °) in the surface acoustic wave device of the example, and Al is made of SiO _{2 for} the standardized film thicknesses of 0.2, 0.3, and 0.4. It is a figure which shows the change of the reflection coefficient at the time of changing the electrode normalized film thickness, and the change of the reflection coefficient in the same conditions of the conventional surface acoustic wave device.

FIG. 35 shows that in the surface acoustic wave device of the example, when the IDT electrode is formed of Au, the normalized film thickness of SiO ₂ is 0.3, the Euler angle of the LiNbO ₃ substrate is changed, and the Au electrode normalized film thickness is changed. Is a diagram showing a change in the electromechanical coefficient K ² .

36 shows an IDT electrode made of Au, a standardized film thickness of SiO ₂ of 0.3, an Euler angle of a LiNbO ₃ substrate, and an Au electrode standardized film thickness in the surface acoustic wave device of the embodiment. Is a diagram showing a change in the reflection coefficient.

<Description of the code>

1: LiTaO ₃ Substrate 1a: Top

1b: groove 2: photoresist layer

2A: photoresist pattern 3: electrode film

4: SiO ₂ 11: surface acoustic wave resonator

12, 13: reflector 21: inorganic material thin film

21A: inorganic material thin film pattern 22: photoresist layer

22A: photoresist pattern 31: surface acoustic wave resonator filter

32: piezoelectric plate 33a, 33b: IDT electrode

34a, 34b: Reflector 48: 2-port surface acoustic wave resonator

48a, 48b: IDT electrode 48c, 48d: reflector

49a: ladder filter 49b: grid filter

51: Ti electrode layer 52: First electrode layer

53: substrate 54: SiO ₂ layer

55: second electrode layer 61: piezoelectric plate

61a: upper 61b: home

61c: inner bottom 61d, 61e: inner side

EMBODIMENT OF THE INVENTION Hereinafter, this invention is made clear by demonstrating specific Example and experimental example of this invention, referring drawings.

1 and 2, a method for manufacturing a surface acoustic wave device according to an embodiment of the present invention will be described.

As shown in FIG. 1A and FIG. 1B, first, a LiTaO ₃ substrate is prepared.

In this embodiment, more specifically, a LiTaO ₃ substrate of (0 °, 126 °, 0 °) is used as the LiTaO ₃ substrate 1 at 36 ° rotating Y plate X propagation and Euler angles. However, about an Euler angle, it can change variously as mentioned later. On the other hand, the relationship of θ = rotation cut angle + 90 ° of Euler angles (φ, θ, ψ) or (φ, θ, ψ) = (60 ° + φ, -θ, ψ) = (60 ° -φ, -θ , 180 ° -ψ) = (φ, 180 ° + θ, 180 ° -ψ) = (φ, θ, 180 ° + ψ).

Next, the photoresist layer 2 is formed on the entire surface 1a of the LiTaO ₃ substrate 1. As the photoresist layer 2, a suitable photoresist material capable of withstanding reactive ion etching (RIE) to be performed later can be used. In the present Example, Clariant Japan company make, positive resist, and item number: AZ-1500 were used. In addition, in the present Example, the thickness of the said photoresist layer 2 was 2 micrometers.

Next, by photosensitive and washing the photoresist layer, as shown in FIG. 1B, the photoresist layer 2 was patterned to form a photoresist pattern 2A. In this photoresist pattern 2A, the photoresist layer is removed at the portion where the IDT electrode is formed later.

Thereafter, reactive ion etching was performed to form a plurality of grooves 1b having a desired depth on the upper surface 1a of the LiTaO ₃ substrate 1 as shown in FIG. 1C. This desired depth is the same dimension as the film thickness of the IDT electrode formed later. However, the depth of the etching may be slightly larger or smaller than the dimension of the film thickness of the IDT electrode.

Next, an Al film was formed into a film by vapor deposition or sputtering. As a result, as shown in FIG. 1D, the Al film, that is, the electrode film 3 is filled in the groove 1b. On the other hand, the Al film is formed on the upper surface of the remaining photoresist pattern 2A.

Thereafter, the LiTaO ₃ substrate was immersed in a peeling solution such as acetone to remove the Al film on the photoresist pattern 2A and the photoresist pattern 2A. Thus, as shown in Figure 1e, and the electrode film (3) is filled in the groove (1b), the upper surface is substantially, flat LiTaO ₃ to give a substrate (1).

Then, as shown in FIG. 1F, a SiO ₂ film 4 was formed on the upper surface. The surface of the SiO ₂ film is planarized. This is because the upper surface 1a of the LiTaO ₃ substrate 1 serving as the base and the upper surface of the electrode film 3 are almost coplanar and almost planarized. Thus, when a SiO ₂ film is formed by a conventional film forming method, the SiO ₂ film is formed. This is because the surface of the _second film can be reliably flattened.

On the other hand, SiO ₂ film formation method is not particularly limited, and may be done by any suitable method such as printing, vapor deposition or sputtering.

1A to 1F, the manufacturing method of the surface acoustic wave device of the present embodiment was explained by only representing the electrode portions. More specifically, the one-port surface acoustic wave shown in plan view in FIG. The resonator 11 was obtained.

On the other hand, the one-port surface acoustic wave resonator 11 includes reflectors 12 and 13 on both sides of the surface acoustic wave propagation direction of the electrode film 3 constituting the IDT electrode. The reflectors 12 and 13 are also formed by the same process as the electrode film 3 which is IDT electrode.

Although the LiTaO ₃ substrate was used in the method of manufacturing the surface acoustic wave device of the present embodiment described above with reference to FIGS. 1A to 1F and the one-port surface acoustic wave resonator 11 shown in plan view in FIG. 2, a LiNbO ₃ substrate was used. Even when a substrate is used, the same configuration can be provided.

Experimental Example 1

For the sake of comparison, a plurality of surface acoustic wave resonators formed in the same manner as in the above-described examples were produced in the following manner, except that they were obtained according to the production method described in Patent Document 1. In Experimental Example 1, a LiTaO ₃ substrate was used.

That is, as the surface acoustic wave resonators of the above-described examples and comparative examples, a plurality of surface acoustic wave resonators were obtained with different electrode film thicknesses. On the other hand, SiO ₂ film normalized film thickness H / λ was set to 0.25. On the other hand, the electrodes in the present specification or the SiO ₂ normalized film thickness of the film, the film thickness when the wavelength of H, IDT in λ, is a value represented by H / λ. The electromechanical coefficient of the surface acoustic wave resonator manufactured as described above was measured. The results are shown in FIG.

3 shows the result of an Example, and a broken line shows the result of a comparative example.

As is apparent from Fig. 3, according to the above embodiment, it can be seen that an electromechanical coupling coefficient equal to or greater than that of the surface acoustic wave resonator of the comparative example is obtained. In particular, in the range where the standardized film thickness H / λ of the electrode is in the range of 0.06 to 0.12, it can be seen that the electromechanical coupling coefficient is about 0.03 higher than that of the surface acoustic wave resonator of the comparative example.

Experimental Example 2

Next, in addition to the surface acoustic wave resonator of the above-mentioned embodiment and the surface acoustic wave resonator of Comparative Example 1, a conventional surface acoustic wave resonator having a non-flat surface of SiO ₂ film was prepared as the surface acoustic wave resonator of Comparative Example 2. In each surface acoustic wave resonator, the Euler angle of the LiTaO ₃ substrate and the standardized film thickness of the SiO ₂ film were the same as those obtained in the results shown in FIG. 3.

Also in Experimental Example 2, a plurality of types of surface acoustic wave resonators were produced by varying the normalized film thickness H / λ of the electrode, and the reflection coefficients were obtained. The results are shown in FIG.

As apparent from Fig. 4, it is understood that the surface acoustic wave resonator of Comparative Example 1 does not increase the reflection coefficient even when the electrode normalized film thickness is increased. In contrast, in the surface acoustic wave resonator of the embodiment, it can be seen that the reflection coefficient becomes sufficiently large as the electrode normalized film thickness increases. In particular, the surface acoustic wave resonator of Comparative Example 2 having unevenness in the surface of the SiO ₂ film had a large insertion loss. have.

Accordingly, it can be seen from the results of FIGS. 3 and 4 that according to the embodiment, the electromechanical coupling coefficient is sufficiently large and the reflection coefficient of sufficient size can be obtained by increasing the electrode film thickness.

(Example of other manufacturing method)

On the other hand, in the above embodiment, the surface acoustic wave resonator 11 is manufactured in accordance with the manufacturing method shown in Figs. 1A to 1F, but the manufacturing method for obtaining the surface acoustic wave device of the present invention is similar to the manufacturing method shown in Fig. It is not limited.

5A to 5D are respective schematic front cross-sectional views for illustrating a second example for manufacturing the surface acoustic wave device of the present invention.

In this manufacturing method, as shown in Figure 5a, first, on the LiTaO ₃ substrate 1, for example to form an inorganic material thin film 21 made of an inorganic material such as SiN or ZnO. Next, a photoresist layer 22 is formed over the entire surface of the inorganic material thin film 21.

Thereafter, the photoresist layer 22 is exposed and developed to pattern the photoresist layer 22 and the inorganic material thin film 21 under the photoresist layer 22. In this way, as shown in FIG. 5B, the inorganic material thin film pattern 21A and the photoresist pattern 22A are obtained.

Then, the photoresist pattern 22A is removed using a solvent. In this way, there can be obtained a structure in the upper surface thereof, the inorganic material thin film pattern (21A) is formed of a piezoelectric substrate as a LiTaO ₃ substrate 1, as shown in Figure 5c.

Then, by reactive ion etching, as shown in FIG. 5D, the region where the inorganic material thin film pattern 21A is not formed is etched. In this way, a plurality of grooves 1b are formed.

Then, an Al film is formed by vapor deposition or sputtering. Thereby, similarly to the structure shown in FIG. 1D, Al is filled in the plurality of grooves, an electrode film is formed, and the electrode film is attached onto the inorganic material thin film pattern 22A. Thereafter, the LiTaO ₃ substrate is immersed in a peeling solution to peel off the inorganic material thin film pattern 21A and the electrode film remaining thereon. In this way, the same structure as that shown in FIG. 1E can be obtained. Therefore, when a SiO ₂ film is formed next, a SiO ₂ film having a flat surface can be formed similarly to the structure shown in FIG. 1F.

Experimental Example 3

Next, in the surface acoustic wave resonator shown in FIG. 2, the Euler angle of the LiTaO ₃ substrate is set to (0 °, 126 °, 0 °), and the standardized film thickness H / λ of the electrode made of Al is variously different. Further, the surface acoustic wave resonators of plural types of examples were fabricated by varying the normalized film thickness of the SiO ₂ film. For comparison, also in the surface acoustic wave resonators of Comparative Example 1 described above, similarly, the electrode normalized film thickness and the normalized film thickness of SiO ₂ were changed to produce a plurality of surface acoustic wave resonators. The reflection coefficients and electromechanical coupling coefficients of the surface acoustic wave resonators thus obtained were obtained. The results are shown in FIGS. 6 and 7, respectively.

6 and 7, solid lines show the results of the examples, and broken lines show the results of the surface acoustic wave resonators of Comparative Example 1. FIG.

As is apparent from Fig. 6, in the surface acoustic wave resonator of the embodiment, a larger reflection coefficient is obtained regardless of the electrode film thickness made of Al and the film thickness of the SiO ₂ film as compared with the surface acoustic wave resonator of Comparative Example 1. I can see your luggage.

As is apparent from FIG. 7, in the surface acoustic wave resonator of the embodiment, regardless of the film thickness of the SiO ₂ film and the film thickness of the electrode made of Al, the electric machine equivalent to or more than the surface acoustic wave resonator of Comparative Example 1 It can also be seen that the binding coefficient is obtained. In particular, even in the region where the standardized film thickness H / λ of the SiO ₂ film is 0.3 or more, according to the embodiment, it can be seen that a sufficient electromechanical coupling coefficient is obtained.

Next, a SiO ₂ film having various standardized film thicknesses was fabricated by using various Euler angle LiTaO ₃ substrates and varying the standardized film thickness H / λ of Al made of 0.06, 0.08 or 0.1. The surface acoustic wave resonators of several types of examples were produced, and the frequency temperature coefficient TCF was measured. The results are shown in FIGS. 8 to 10.

On the other hand, TCF is defined by the following equation.

TCF = ((frequency at 80 ° C)-(frequency at -20 ° C)) / (100 x (frequency at 25 ° C))

From the results in FIGS. 8 to 10, regardless of the electrode normalized film thickness of Al, the film thickness of the SiO ₂ film is increased, thereby shifting the frequency temperature coefficient TCF from the negative value to the positive value side, and also positive. It can be seen that the area can be enlarged. This is because the SiO ₂ film has a positive frequency temperature coefficient.

8 to 10, in the case of using various Euler angle LiTaO ₃ substrates, in any case, by increasing the film thickness of the SiO ₂ film, the frequency temperature coefficient can be increased, and due to the difference in the Euler angle You can see that there are very few cars. Preferably, when the normalized film thickness H / λ of the SiO ₂ film is in the range of 0.15 to 0.4, more preferably in the range of 0.2 to 0.35, the absolute value of the frequency temperature coefficient TCF is 15 ppm / 占 폚 or less, and 10 ppm /, respectively. It can be seen that the temperature can be reduced to less than or equal to ° C, so that good frequency temperature characteristics are obtained.

Next, in the surface acoustic wave resonator of the embodiment, the Euler angle of the LiTaO ₃ substrate to be used is changed in various ways, and the electrode normalized film thickness and the normalized film thickness of the SiO ₂ film are changed in various ways, thereby providing a plurality of types of elasticity. A surface wave resonator was fabricated. The attenuation constant α of the obtained surface acoustic wave resonator was measured. The results are shown in FIGS. 11 to 16.

11 to 13 show a change in the attenuation constant α at the resonance frequency of the surface acoustic wave resonator, and FIGS. 14 to 16 show a change in the attenuation constant α at the anti-resonant frequency. Therefore, when a filter is formed, if the attenuation constant α shown in Figs. 11 to 13 is made small, the steepness at the low pass side of the filter characteristic can be increased. Further, it can be seen that if the attenuation constant α shown in Figs. 14 to 16 can be made small, the steepness at the high pass side of the filter can be increased.

As is apparent from Figs. 11 to 13, the attenuation constant α is remarkably small by being not affected by the electrode film thickness made of Al or the film thickness of the SiO ₂ film, but rather by setting the θ of the Euler angle of the LiTaO ₃ substrate to an appropriate range. It can be seen that. That is, from FIG. 11 to FIG. 13, when it is desired to increase the steepness at the passband low pass side of the filter, the Euler angle in any one of the ranges shown in Table 7 below, more preferably any one shown in Table 8 It was found that the range should be.

α = 0.05 or less θ of Euler angles (0, θ, 0) 0.125≤SiO ₂ layer thickness≤0.2 0.02≤Al thickness <0.04 (0, 114 ° to 142 °, 0) 0.04≤Al thickness <0.06 (0, 115 ° to 143 °, 0) 0.06≤Al thickness <0.1 (0, 113 ° to 145 °, 0) 0.1≤Al thickness≤0.14 (0, 112 ° to 146 °, 0) 0.2 <SiO ₂ layer thickness≤0.275 0.02≤Al thickness <0.04 (0, 113 ° to 140 °, 0) 0.04≤Al thickness <0.06 (0, 113 ° to 140 °, 0) 0.06≤Al thickness <0.1 (0, 111 ° to 140 °, 0) 0.1≤Al thickness≤0.14 (0, 111 ° to 140 °, 0) 0.275 <SiO ₂ layer thickness≤0.35 0.02≤Al thickness <0.04 (0, 111 ° to 137 °, 0) 0.04≤Al thickness <0.06 (0, 111 ° to 137 °, 0) 0.06≤Al thickness <0.1 (0, 109 ° to 136 °, 0) 0.1≤Al thickness≤0.14 (0, 107 ° to 136 °, 0)

Both SiO ₂ layer thickness and Al thickness are standardized film thickness H / λ

θ of Euler angle (0, θ, 0) of α = 0.025 or less 0.125≤SiO ₂ layer thickness≤0.2 0.02≤Al thickness <0.04 (0, 118 ° to 137 °, 0) 0.04≤Al thickness <0.06 (0, 117 ° to 139 °, 0) 0.06≤Al thickness <0.1 (0, 117 ° to 141 °, 0) 0.1≤Al thickness≤0.14 (0, 116 ° to 141 °, 0) 0.2 <SiO ₂ layer thickness≤0.275 0.02≤Al thickness <0.04 (0, 115 ° to 137 °, 0) 0.04≤Al thickness <0.06 (0, 115 ° to 138 °, 0) 0.06≤Al thickness <0.1 (0, 115 ° to 138 °, 0) 0.1≤Al thickness≤0.14 (0, 114 ° to 136 °, 0) 0.275 <SiO ₂ layer thickness≤0.35 0.02≤Al thickness <0.04 (0, 113 ° to 137 °, 0) 0.04≤Al thickness <0.06 (0, 113 ° to 137 °, 0) 0.06≤Al thickness <0.1 (0, 111 ° to 136 °, 0) 0.1≤Al thickness≤0.14 (0, 112 ° to 133 °, 0)

Both SiO ₂ layer thickness and Al thickness are standardized film thickness H / λ

14 to 16, when increasing the steepness of the high frequency side of the filter waveform, the Euler angle in any one of the ranges shown in Table 9 below, more preferably in any one of Table 10 You can see that by selecting the range.

α = 0.05 or less θ of Euler angles (0, θ, 0) 0.125≤SiO ₂ layer thickness≤0.20 0.02≤Al thickness <0.04 (0, 119 ° to 152 °, 0) 0.04≤Al thickness <0.06 (0, 120 ° to 153 °, 0) 0.06≤Al thickness <0.1 (0, 124 ° to 158 °, 0) 0.1≤Al thickness≤0.14 (0, 128 ° to 155 °, 0) 0.20 <SiO ₂ layer thickness≤0.275 0.02≤Al thickness <0.04 (0, 123 ° to 152 °, 0) 0.04≤Al thickness <0.06 (0, 124.5 ° to 153 °, 0) 0.06≤Al thickness <0.1 (0, 123.5 ° to 154 °, 0) 0.1≤Al thickness≤0.14 (0, 119 ° to 157 °, 0) 0.275 <SiO ₂ layer thickness≤0.35 0.02≤Al thickness <0.04 (0, 124 ° to 150 °, 0) 0.04≤Al thickness <0.06 (0, 124 ° to 146 °, 0) 0.06≤Al thickness <0.1 (0, 114 ° to 149 °, 0) 0.1≤Al thickness≤0.14 (0, 103 ° to 148 °, 0)

Both SiO ₂ layer thickness and Al thickness are standardized film thickness H / λ

θ of Euler angle (0, θ, 0) of α = 0.025 or less 0.125≤SiO ₂ layer thickness≤0.20 0.02≤Al thickness <0.04 (0, 123 ° to 148 °, 0) 0.04≤Al thickness <0.06 (0, 127 ° to 149 °, 0) 0.06≤Al thickness <0.1 (0, 127.5 ° to 154 °, 0) 0.1≤Al thickness≤0.14 (0, 131 ° to 158 °, 0) 0.20 <SiO ₂ layer thickness≤0.275 0.02≤Al thickness <0.04 (0, 127 ° to 148 °, 0) 0.04≤Al thickness <0.06 (0, 128 ° to 149 °, 0) 0.06≤Al thickness <0.1 (0, 128 ° to 149 °, 0) 0.1≤Al thickness≤0.14 (0, 124 ° to 155 °, 0) 0.275 <SiO ₂ layer thickness≤0.35 0.02≤Al thickness <0.04 (0, 128 ° to 146 °, 0) 0.04≤Al thickness <0.06 (0, 128 ° to 146 °, 0) 0.06≤Al thickness <0.1 (0, 119 ° to 146 °, 0) 0.1≤Al thickness≤0.14 (0, 110 ° to 145 °, 0)

Both SiO ₂ layer thickness and Al thickness are standardized film thickness H / λ

On the other hand, in the present invention, preferably, the IDT electrode is formed by a multilayer structure of an electrode layer containing Al as a main component and an electrode layer having higher electric power resistance than Al. 17A and 17B are partial cutaway cross-sectional views for explaining such a multilayer IDT electrode.

In FIG. 17A, an electrode layer 52 containing Al as a main component is formed on a Ti electrode layer 51 having a film thickness of 50 nm as an electrode layer having higher electric power resistance than Al. Here, the thickness of the electrode layer 52 is thicker than the thickness of the Ti electrode layer 51, and the upper surface of the electrode layer 52 is coplanar with the upper surface of the substrate 53. On the other hand, the SiO ₂ layer 54 is formed so as to cover the substrate 53 and the IDT electrode.

In addition, in FIG. 17B, the electrode layer 52 containing Al as a main component is formed on the Ti electrode layer 51 having a film thickness of 50 nm as the second electrode layer having a higher density than Al. Further, another second electrode layer 55 made of Ti having a film thickness of 50 nm is formed on the first electrode layer 52. The upper surface of the second electrode layer 55 is coplanar with the upper surface of the substrate 53. Thus, the IDT electrode may be formed of a laminated film in which two or three or more electrode layers are laminated. In addition, as is apparent from the present embodiment, in the laminated film, the second electrode layer having a higher density than Al, which is laminated on the first electrode layer made of Al or an alloy containing Al as a main component, does not necessarily have to be a single layer. It may be a plurality of layers. In the case of using a plurality of second electrode layers, as in the present embodiment, the first electrode layer may be sandwiched between the plurality of second electrode layers, and the second electrode layer is provided only on one side of the first electrode layer. You may laminate.

As shown in FIGS. 17A and 17B, the IDT electrode is formed of a laminated film having a first electrode layer containing Al or Al as a main component and a second electrode layer having a higher density than Al, thereby forming an IDT electrode with a piezoelectric plate. It is possible to increase the bonding strength, to prevent deterioration of the IDT electrode due to stress migration, and to improve the power resistance of the IDT electrode.

On the other hand, in FIG. 17B, although the 2nd electrode layers 51 and 55 which consist of Ti were laminated | stacked on and under the 1st electrode layer 52 which has Al or Al as a main component, the 2nd electrode layer which consists of Ti is Al or It is good also as a structure which pinches | interposes between a pair of 1st electrode layer which has Al as a main component. Even in that case, the electric power resistance can be improved. Alternatively, the first electrode layer containing Al or Al as a main component and the second electrode layer may be alternately stacked to form an IDT electrode having a multilayer structure of four or more layers.

On the other hand, in FIG. 17A and FIG. 17B, although the 2nd electrode layer which consists of Ti was shown as a 2nd electrode layer with a higher density than Al, metals, such as Cu, W, Cr, etc. which are metals with a higher density than Al other than Ti are shown. You may use it. As with AlCu, an alloy of Al and a metal having a higher density than Al may be used, or an alloy mainly composed of a plurality of metals having a higher density than Al, such as NiCr. Also in these cases, the same effects as in the case of the above embodiment can be obtained.

The present invention can be applied to various surface acoustic wave devices. An example of such a surface acoustic wave device is shown in FIG. 18. 18 is a schematic plan view of the two-port surface acoustic wave resonator 48. Here, IDTs 48a and 48b and reflectors 48c and 48d are formed on the piezoelectric substrate. Further, the longitudinally coupled type surface acoustic wave resonator filter may be configured using the same electrode structure as the two-port surface acoustic wave resonator 48 shown in FIG.

19 and 20 are schematic plan views showing the electrode structures of the ladder filter and the lattice filter, respectively. By forming electrode structures such as the ladder filter 49a and the lattice filter 49b shown in Figs. 19 and 20 on the piezoelectric plate, the ladder filter and the lattice filter can be configured according to the present invention.

However, the present invention is not limited to the surface acoustic wave device having the electrode structure shown in FIGS. 18 to 20, and can be applied to various surface acoustic wave devices.

In the surface acoustic wave device according to the present invention, a surface acoustic wave device using a leaky acoustic wave is preferably configured. Japanese Laid-Open Patent Publication No. 6-164306 discloses a surface acoustic wave device having an electrode made of a heavy metal such as Au, and a surface acoustic wave device using a love wave without propagation attenuation. Here, by using a heavy metal as an electrode, the sound velocity of the surface acoustic wave propagates is slower than the slow transverse bulk wave of the substrate, whereby the leakage component disappears, and the love wave as the surface acoustic wave is used.

In the surface acoustic wave device according to the present invention, an IDT electrode is formed by filling electrode materials in a plurality of grooves formed in a piezoelectric plate. Here, Preferably, the inside angle of the said groove | channel is 90 degrees or less, More preferably, it is the range of 50 degrees-80 degrees. This will be described with reference to FIGS. 21 and 22.

Fig. 21 is a schematic front sectional view for explaining the cabinet of the groove formed in the piezoelectric plate. That is, a plurality of grooves 61b are formed in the upper surface 61a of the piezoelectric substrate 61. The groove 61b is surrounded by an inner bottom surface 61c and a pair of inner surfaces 61d and 61e connecting the inner bottom surface 61c and the upper surface 61a. Metal is filled in this groove 61b, for example, the IDT electrode 3 shown in FIG. 1E is formed. Here, the internal angle X of the groove 61b is an angle formed by the upper surface 61a of the piezoelectric plate 61 and the inner surface 61d or 61e, and is an angle located in the groove 61b. On the other hand, in the piezoelectric plate 1 shown in FIG. 1E, the inner angle of the groove is 90 degrees. In FIG. 21, the cabinet X is at an angle smaller than 90 ° as shown.

Fig. 22 is the same as that of the first embodiment, except that the electromechanical coupling coefficient in the case where the grooves of various cabinets are formed in the LiTaO ₃ substrate, and the IDT electrode made of Al is formed in the grooves in various thicknesses. It is a figure which shows a change.

In addition, 22 of the vertical axis shows the value of the electromechanical coupling coefficient K ² to normalized based on the value of the electromechanical coupling coefficient when the cabinet of the groove is 90 °. The electromechanical coupling coefficient is required to be 0.04 or more if necessary. On the other hand, when the internal angle of the surface acoustic wave device and the groove of the above embodiment is 90 °, the electromechanical coupling coefficient is 0.05. Therefore, when the electromechanical coupling coefficient of FIG. 22 is 0.8 or more, it can be seen that the electromechanical coupling coefficient is 0.04 or more. As is apparent from Fig. 22, when the internal angle X of the groove is in the range of 45 ° to 90 °, that is, 90 ° or less, the normalized film thickness of Al is in the range of 0.04 to 0.12, regardless of the film thickness. It can be seen that the mechanical coupling coefficient is 0.87 or more, so that an electromechanical coupling coefficient of sufficient size is obtained.

On the other hand, at the time of manufacture of a surface acoustic wave device, a deviation may arise in the cabinet X of the said groove for manufacturing reasons. However, as is apparent from Fig. 22, it can be seen that the electromechanical coupling coefficient can be made large enough, regardless of the film thickness of the IDT electrode, in the groove angle of 90 ° or less. In particular, since the minimum value of the electromechanical coupling coefficient exists around the internal angle X of the groove at around 60 ° to 70 °, the internal angle X of the groove is set at around this minimum value, i.e., around 50 ° to 80 °. It can be seen that even if the cabinet of the groove fluctuates, the variation of the electromechanical coupling coefficient can be made very small. Therefore, it turns out that the dispersion | variation in the characteristic of the surface acoustic wave device as a product can be made small.

On the other hand, even when not only Al but also when IDT electrode is formed using the alloy which has Al as a main component, or when IDT electrode which consists of a laminated film as mentioned above is formed, the internal angle X of a groove | channel is 60 degrees-70 degrees. In the vicinity, since there exists a minimum value of the standardized electromechanical coupling coefficient, it is likewise preferable that the inside angle X of the groove is set to 90 ° or less, more preferably 50 ° to 80 °.

FIG. 23 is a diagram showing a change in the electromechanical coefficient K ² when the internal angle X of the groove obtained in the same manner as in FIG. 22 is changed except that the film thickness of the SiO ₂ film is changed to 0.2λ. As is apparent from FIG. 23, even when the standardized film thickness of the SiO ₂ film is changed to 0.2, it tends to be almost the same as in the case of FIG. 22, and the electromechanical coupling coefficient K ² is in the range of the groove angle of 50 ° to 80 °. It can be seen that the deviation can be made small.

FIG. 24 is a diagram showing a relationship between the internal angle X and the electromechanical coupling coefficient K ² obtained in the same manner as in FIG. 22 except that θ of the Euler angle is changed from 126 ° to 120 °. As is apparent from Fig. 24, even when the Euler angle θ is changed, the deviation of the electromechanical coupling coefficient K ² becomes smaller when the inner angle X of the groove exhibiting the same tendency as in Fig. 22 is in the range of 50 to 80 °. It can be seen that there is a point.

Fig. 25 is a view showing a change in the electromechanical coupling coefficient with respect to the inner angle of the groove when the film thickness of the IDT is fixed and θ of the Euler angle is 120 °, 126 ° and 132 °. Also in FIG. 25, the same tendency as in the case of FIG. 22 is shown. When the angle of the groove is in the range of 50 to 80 °, even if the angle of the groove varies, the variation of the electromechanical coupling coefficient can be made very small. It can be seen that there is a point.

Next, an embodiment of a surface acoustic wave device using a LiNbO ₃ substrate as a piezoelectric substrate will be described. In the surface acoustic wave resonator shown in FIG. 2, the Euler angle of the LiNbO ₃ substrate is varied, the standardized film thickness of the electrode made of Al is varied, and the standardized film thickness of the SiO ₂ film is varied. Thus, surface acoustic wave resonators of a plurality of embodiments were created. In addition, the comparative example having the same structure as those discussed as a comparative example in Fig. 3 for comparison were prepared by using a LiNbO ₃ substrate.

Fig. 26 shows changes in the normalized film thickness of the SiO ₂ film when the Euler angle of the LiNbO ₃ substrate is set to (0 °, 170 °, 0 °) and the Al standardized film thickness is 0.02, 0.06, 0.1, 0.16. The change in TCF is shown. As apparent from Fig. 26, when the standardized film thickness of the SiO ₂ film is in the range of 0.2 to 0.4, it can be seen that there is a standardized film thickness of the Al electrode that can make the TCF in the range of ± 30 ppm / 占 폚. In other words, when the standardized film thickness of the SiO ₂ film is small, the standardized film thickness of Al may be reduced. When the standardized film thickness of the SiO ₂ film is large, the standardized film thickness of Al may be increased. When the normalized film thickness of the SiO ₂ film is in the range of 0.25 to 0.3, the TCF can be in the range of ± 30 ppm / ° C in all the ranges in which the Al standardized film thickness is from 0.02 to 0.16. Also in other Euler angles, it shows a good TCF by the SiO ₂ film normalized film thickness in the above range.

Fig. 27 shows the electromechanical coupling coefficient K when the Al standardized film thickness is varied in various normalized film thicknesses of the SiO ₂ film when the Euler angle of the LiNbO ₃ substrate is (0 °, 105 °, 0 °). ^It is a figure which shows the change of ² in parallel with the said comparative example and this Example.

Similarly, FIG. 28 is a diagram showing a change in reflection coefficient under the same conditions as in FIG. 27.

Likewise, FIGS. 29 and 30 show Euler angles (0 °, 131 °, 0 °), FIGS. 31 and 32 show Euler angles (0 °, 154 °, 0 °), FIGS. 33 and 34 Euler Except for setting the angle to (0 °, 170 °, 0 °), the drawings show the change in the electromechanical coupling coefficient K ^{2 and} the change in the reflection coefficient under the same conditions as those in FIGS. 27 and 2, respectively. .

27, 29, 31, and 33, in the region where Al standardized film thickness is 0.04 or more, it can be seen that the electromechanical coefficient K ² of this embodiment is all larger than that of the comparative example. 28, 30, 32, and 34, it can be seen that the reflection coefficients show almost the same values as in the comparative example. In particular, in the region where the standardized film thickness of Al is large, the electromechanical coefficient K ² is sufficiently large and the reflection coefficient is also large compared with the comparative example.

Even when the Euler angle is in the range of (0 °, 85 ° to 120 °, 0 °), the result is almost the same as the result shown in FIGS. 27 and 28, and (0 °, 90 ° to 110 °, 0 °). More preferable results were obtained when it was in a range. Also, when the Euler angle is in the range of (0 °, 125 ° to 141 °, 0 °), the result is almost the same as the result shown in FIGS. 29 and 30, and (0 °, 125 ° to 136 °, 0 °). In the range of), more preferable results were obtained. Even when the Euler angle is in the range of (0 °, 145 ° to 164 °, 0 °), the result is almost the same as the result shown in FIGS. 31 and 32, and (0 °, 149 ° to 159 °, 0 °). More preferable results were obtained when it was in a range. Even when the Euler angle is in the range of (O °, 160 ° to 180 °, 0 °), the result is almost the same as the result shown in FIGS. 33 and 34, and of (0 °, 165 ° to 175 °, 0 °). More preferable results were obtained when it was in a range.

On the other hand, the present inventors, in the surface acoustic wave device of the embodiment using the LiNbO ₃ substrate, as in the surface acoustic wave device of the above-described embodiment using the LiTaO ₃ substrate, the cabinet of the groove 61b shown in Fig. 1E. As a result of various changes in X, when the cabinet is in the range of 45 ° to 90 °, the electromechanical coefficient is sufficiently large, and in particular, when the angle is set in the range of 50 ° to 80 °, It was confirmed that the variation in the mechanical coupling coefficient can be made very small. That is, similarly to the case of using the LiTaO ₃ substrate, also in the case of using the LiNbO ₃ substrate, by setting the inner angle of the groove to the specific range, the improvement of the electromechanical coupling coefficient and the deviation of the electromechanical coupling coefficient can be similarly reduced Confirmed that it can.

In addition, the inventors of the present application also examined LiNbO ₃ in metals other than Al electrodes. The results are shown in FIGS. 35 and 36. Fig. 35 shows the Au electrode normalized film when the IDT electrode is formed of Au, the normalized film thickness of SiO ₂ is 0.3, and the Euler angle of the LiNbO ₃ substrate is changed in the surface acoustic wave device of the above embodiment. a view showing the change in electromechanical coupling coefficient K ² at the time is changed in thickness. 36 shows the Au electrode in the surface acoustic wave device of the above embodiment, wherein the IDT electrode is formed of Au, the normalized film thickness of SiO ₂ is 0.3, and the Euler angle of the LiNbO ₃ substrate is changed. It is a figure which shows the change of the reflection coefficient when changing a normalized film thickness. In any Euler angle, an electromechanical coupling coefficient K ² equal to or greater than Al is obtained, and the reflection coefficient can obtain a reflection coefficient larger than that of Al. Although the drawings are omitted, the electromechanical coupling coefficient K ² and the reflection coefficient close to Au are obtained also for metals such as Cu, Ni, Mo, Ag, Ta, and W. The temperature characteristics are excellent, and the electromechanical coupling coefficient K ² is obtained. A surface acoustic wave device having a large and large reflection coefficient can be obtained.

Claims (20)

A LiTaO ₃ substrate having a plurality of grooves formed on an upper surface thereof; An IDT electrode formed by filling Al into the groove; A SiO ₂ layer formed to cover the LiTaO ₃ substrate and the IDT electrode, the top surface of the SiO ₂ layer being flat; Let the wavelength of the surface acoustic wave be λ, Euler angles of the LiTaO ₃ substrate is in any one of the ranges shown in Table 11 below. The film thickness of the IDT electrode is in a range where the Euler angles of the LiTaO ₃ substrate and the Euler angles described in Table 11 are shown at corresponding positions. The thickness of the SiO ₂ layer is in the range where the film thickness of the IDT electrode and the Al thickness shown in Table 11 are shown at corresponding positions. α = 0.05 or less θ of Euler angles (0, θ, 0) 0.125≤SiO ₂ layer thickness≤0.2 0.02≤Al thickness <0.04 (0, 114 ° to 142 °, 0) 0.04≤Al thickness <0.06 (0, 115 ° to 143 °, 0) 0.06≤Al thickness <0.1 (0, 113 ° to 145 °, 0) 0.1≤Al thickness≤0.14 (0, 112 ° to 146 °, 0) 0.2 <SiO ₂ layer thickness≤0.275 0.02≤Al thickness <0.04 (0, 113 ° to 140 °, 0) 0.04≤Al thickness <0.06 (0, 113 ° to 140 °, 0) 0.06≤Al thickness <0.1 (0, 111 ° to 140 °, 0) 0.1≤Al thickness≤0.14 (0, 111 ° to 140 °, 0) 0.275 <SiO ₂ layer thickness≤0.35 0.02≤Al thickness <0.04 (0, 111 ° to 137 °, 0) 0.04≤Al thickness <0.06 (0, 111 ° to 137 °, 0) 0.06≤Al thickness <0.1 (0, 109 ° to 136 °, 0) 0.1≤Al thickness≤0.14 (0, 107 ° to 136 °, 0) Both SiO ₂ layer thickness and Al thickness are standardized film thickness H / λ The method of claim 1 wherein in the range of any one shown in Table 12, the Euler angles of the LiTaO ₃ to the substrate, The film thickness of the IDT electrode is in a range where the Euler angles of the LiTaO ₃ substrate and the Euler angles shown in Table 12 are shown at corresponding positions. The surface thickness of the SiO ₂ layer is in the range where the film thickness of the IDT electrode and the Al thickness shown in Table 12 correspond to the corresponding positions. θ of Euler angle (0, θ, 0) of α = 0.025 or less 0.125≤SiO ₂ layer thickness≤0.2 0.02≤Al thickness <0.04 (0, 118 ° to 137 °, 0) 0.04≤Al thickness <0.06 (0, 117 ° to 139 °, 0) 0.06≤Al thickness <0.1 (0, 117 ° to 141 °, 0) 0.1≤Al thickness≤0.14 (0, 116 ° to 141 °, 0) 0.2 <SiO ₂ layer thickness≤0.275 0.02≤Al thickness <0.04 (0, 115 ° to 137 °, 0) 0.04≤Al thickness <0.06 (0, 115 ° to 138 °, 0) 0.06≤Al thickness <0.1 (0, 115 ° to 138 °, 0) 0.1≤Al thickness≤0.14 (0, 114 ° to 136 °, 0) 0.275 <SiO ₂ layer thickness≤0.35 0.02≤Al thickness <0.04 (0, 113 ° to 137 °, 0) 0.04≤Al thickness <0.06 (0, 113 ° to 137 °, 0) 0.06≤Al thickness <0.1 (0, 111 ° to 136 °, 0) 0.1≤Al thickness≤0.14 (0, 112 ° to 133 °, 0) Both SiO ₂ layer thickness and Al thickness are standardized film thickness H / λ A LiTaO ₃ substrate having a plurality of grooves formed on an upper surface thereof; An IDT electrode formed by filling Al into the groove; A SiO ₂ layer formed to cover the LiTaO ₃ substrate and the IDT electrode, the top surface of the SiO ₂ layer being flat; Let the wavelength of the surface acoustic wave be λ, Euler angles of the LiTaO ₃ substrate is in any one of the ranges shown in Table 13 below. The film thickness of the IDT electrode is in a range where the Euler angles of the LiTaO ₃ substrate and the Euler angles described in Table 13 are shown at corresponding positions. The thickness of the SiO ₂ layer is in the range where the film thickness of the IDT electrode and the Al thickness shown in Table 13 are shown at corresponding positions. α = 0.05 or less θ of Euler angles (0, θ, 0) 0.125≤SiO ₂ layer thickness≤0.20 0.02≤Al thickness <0.04 (0, 119 ° to 152 °, 0) 0.04≤Al thickness <0.06 (0, 120 ° to 153 °, 0) 0.06≤Al thickness <0.1 (0, 124 ° to 158 °, 0) 0.1≤Al thickness≤0.14 (0, 128 ° to 155 °, 0) 0.20 <SiO ₂ layer thickness≤0.275 0.02≤Al thickness <0.04 (0, 123 ° to 152 °, 0) 0.04≤Al thickness <0.06 (0, 124.5 ° to 153 °, 0) 0.06≤Al thickness <0.1 (0, 123.5 ° to 154 °, 0) 0.1≤Al thickness≤0.14 (0, 119 ° to 157 °, 0) 0.275 <SiO ₂ layer thickness≤0.35 0.02≤Al thickness <0.04 (0, 124 ° to 150 °, 0) 0.04≤Al thickness <0.06 (0, 124 ° to 146 °, 0) 0.06≤Al thickness <0.1 (0, 114 ° to 149 °, 0) 0.1≤Al thickness≤0.14 (0, 103 ° to 148 °, 0) Both SiO ₂ layer thickness and Al thickness are standardized film thickness H / λ 4. The method of claim 3, in the range of any one shown in Table 14 of the Euler angles of the LiTaO ₃ to the substrate, The film thickness of the IDT electrode is in a range where the Euler angles of the LiTaO ₃ substrate and the Euler angles shown in Table 14 are shown at corresponding positions. The thickness of the SiO ₂ layer is in the range where the film thickness of the IDT electrode and the Al thickness shown in Table 14 are shown at corresponding positions. θ of Euler angle (0, θ, 0) of α = 0.025 or less 0.125≤SiO ₂ layer thickness≤0.20 0.02≤Al thickness <0.04 (0, 123 ° to 148 °, 0) 0.04≤Al thickness <0.06 (0, 127 ° to 149 °, 0) 0.06≤Al thickness <0.1 (0, 127.5 ° to 154 °, 0) 0.1≤Al thickness≤0.14 (0, 131 ° to 158 °, 0) 0.20 <SiO ₂ layer thickness≤0.275 0.02≤Al thickness <0.04 (0, 127 ° to 148 °, 0) 0.04≤Al thickness <0.06 (0, 128 ° to 149 °, 0) 0.06≤Al thickness <0.1 (0, 128 ° to 149 °, 0) 0.1≤Al thickness≤0.14 (0, 124 ° to 155 °, 0) 0.275 <SiO ₂ layer thickness≤0.35 0.02≤Al thickness <0.04 (0, 128 ° to 146 °, 0) 0.04≤Al thickness <0.06 (0, 128 ° to 146 °, 0) 0.06≤Al thickness <0.1 (0, 119 ° to 146 °, 0) 0.1≤Al thickness≤0.14 (0, 110 ° to 145 °, 0) Both SiO ₂ layer thickness and Al thickness are standardized film thickness H / λ The surface acoustic wave device as claimed in claim 1, wherein the Euler angle of the LiTaO ₃ substrate is in a range satisfying the Euler angles shown in Table 11 and Table 15 below. α = 0.05 or less θ of Euler angles (0, θ, 0) 0.125≤SiO ₂ layer thickness≤0.20 0.02≤Al thickness <0.04 (0, 119 ° to 152 °, 0) 0.04≤Al thickness <0.06 (0, 120 ° to 153 °, 0) 0.06≤Al thickness <0.1 (0, 124 ° to 158 °, 0) 0.1≤Al thickness≤0.14 (0, 128 ° to 155 °, 0) 0.20 <SiO ₂ layer thickness≤0.275 0.02≤Al thickness <0.04 (0, 123 ° to 152 °, 0) 0.04≤Al thickness <0.06 (0, 124.5 ° to 153 °, 0) 0.06≤Al thickness <0.1 (0, 123.5 ° to 154 °, 0) 0.1≤Al thickness≤0.14 (0, 119 ° to 157 °, 0) 0.275 <SiO ₂ layer thickness≤0.35 0.02≤Al thickness <0.04 (0, 124 ° to 150 °, 0) 0.04≤Al thickness <0.06 (0, 124 ° to 146 °, 0) 0.06≤Al thickness <0.1 (0, 114 ° to 149 °, 0) 0.1≤Al thickness≤0.14 (0, 103 ° to 148 °, 0) Both SiO ₂ layer thickness and Al thickness are standardized film thickness H / λ The surface acoustic wave device according to claim 1, wherein the Euler angle of the LiTaO ₃ substrate is in a range which satisfies the Euler angles shown in Table 11 and Table 16 below. θ of Euler angle (0, θ, 0) of α = 0.025 or less 0.125≤SiO ₂ layer thickness≤0.20 0.02≤Al thickness <0.04 (0, 123 ° to 148 °, 0) 0.04≤Al thickness <0.06 (0, 127 ° to 149 °, 0) 0.06≤Al thickness <0.1 (0, 127.5 ° to 154 °, 0) 0.1≤Al thickness≤0.14 (0, 131 ° to 158 °, 0) 0.20 <SiO ₂ layer thickness≤0.275 0.02≤Al thickness <0.04 (0, 127 ° to 148 °, 0) 0.04≤Al thickness <0.06 (0, 128 ° to 149 °, 0) 0.06≤Al thickness <0.1 (0, 128 ° to 149 °, 0) 0.1≤Al thickness≤0.14 (0, 124 ° to 155 °, 0) 0.275 <SiO ₂ layer thickness≤0.35 0.02≤Al thickness <0.04 (0, 128 ° to 146 °, 0) 0.04≤Al thickness <0.06 (0, 128 ° to 146 °, 0) 0.06≤Al thickness <0.1 (0, 119 ° to 146 °, 0) 0.1≤Al thickness≤0.14 (0, 110 ° to 145 °, 0) Both SiO ₂ layer thickness and Al thickness are standardized film thickness H / λ The surface acoustic wave device according to claim 2, wherein the Euler angle of the LiTaO ₃ substrate is in a range satisfying the Euler angles shown in Table 12 and Table 17 below. α = 0.05 or less θ of Euler angles (0, θ, 0) 0.125≤SiO ₂ layer thickness≤0.20 0.02≤Al thickness <0.04 (0, 119 ° to 152 °, 0) 0.04≤Al thickness <0.06 (0, 120 ° to 153 °, 0) 0.06≤Al thickness <0.1 (0, 124 ° to 158 °, 0) 0.1≤Al thickness≤0.14 (0, 128 ° to 155 °, 0) 0.20 <SiO ₂ layer thickness≤0.275 0.02≤Al thickness <0.04 (0, 123 ° to 152 °, 0) 0.04≤Al thickness <0.06 (0, 124.5 ° to 153 °, 0) 0.06≤Al thickness <0.1 (0, 123.5 ° to 154 °, 0) 0.1≤Al thickness≤0.14 (0, 119 ° to 157 °, 0) 0.275 <SiO ₂ layer thickness≤0.35 0.02≤Al thickness <0.04 (0, 124 ° to 150 °, 0) 0.04≤Al thickness <0.06 (0, 124 ° to 146 °, 0) 0.06≤Al thickness <0.1 (0, 114 ° to 149 °, 0) 0.1≤Al thickness≤0.14 (0, 103 ° to 148 °, 0) Both SiO ₂ layer thickness and Al thickness are standardized film thickness H / λ The surface acoustic wave device according to claim 2, wherein the Euler angle of the LiTaO ₃ substrate is in a range satisfying the Euler angles shown in Table 12 and Table 18 below. θ of Euler angle (0, θ, 0) of α = 0.025 or less 0.125≤SiO ₂ layer thickness≤0.20 0.02≤Al thickness <0.04 (0, 123 ° to 148 °, 0) 0.04≤Al thickness <0.06 (0, 127 ° to 149 °, 0) 0.06≤Al thickness <0.1 (0, 127.5 ° to 154 °, 0) 0.1≤Al thickness≤0.14 (0, 131 ° to 158 °, 0) 0.20 <SiO ₂ layer thickness≤0.275 0.02≤Al thickness <0.04 (0, 127 ° to 148 °, 0) 0.04≤Al thickness <0.06 (0, 128 ° to 149 °, 0) 0.06≤Al thickness <0.1 (0, 128 ° to 149 °, 0) 0.1≤Al thickness≤0.14 (0, 124 ° to 155 °, 0) 0.275 <SiO ₂ layer thickness≤0.35 0.02≤Al thickness <0.04 (0, 128 ° to 146 °, 0) 0.04≤Al thickness <0.06 (0, 128 ° to 146 °, 0) 0.06≤Al thickness <0.1 (0, 119 ° to 146 °, 0) 0.1≤Al thickness≤0.14 (0, 110 ° to 145 °, 0) Both SiO ₂ layer thickness and Al thickness are standardized film thickness H / λ The surface acoustic wave device according to any one of claims 1 to 8, wherein an upper surface of the IDT electrode and an upper surface of the LiTaO ₃ substrate are coplanar. 9. The groove of claim 1, wherein the groove is surrounded by an inner bottom surface, a pair of inner surfaces connecting the inner bottom surface and the upper surface of the LiTaO ₃ substrate, and the inner surface. A surface acoustic wave device characterized in that the inner angle of the groove formed by the upper surface of the LiTaO ₃ substrate is in the range of 45 ° to 90 °. A LiNbO ₃ substrate having a plurality of grooves formed on an upper surface thereof; An IDT electrode formed by filling Al into the groove; A SiO ₂ layer formed to cover the LiNbO ₃ substrate and the IDT electrode, the top surface of the SiO ₂ layer being flat; Let the wavelength of the surface acoustic wave be λ, The standardized film thickness of the said IDT electrode is 0.04-0.16, The normalized film thickness of the said SiO ₂ layer is 0.2-0.4, The surface acoustic wave device characterized in that the range of any one shown in Table 19 for each of the Euler to the LiNbO ₃ substrate. Θ of Euler angles (0 °, θ, 0 °) (0 °, 85 ° to 120 °, 0 °) (0 °, 125 ° to 141 °, 0 °) (0 °, 145 ° to 164 °, 0 °) (0 °, 160 ° ~ 180 °, 0 °) The surface acoustic wave device as claimed in claim 11, wherein the Euler angle of the LiNbO ₃ substrate is in any one of the ranges shown in Table 20 below. Θ of Euler angles (0 °, θ, 0 °) (0 °, 90 ° to 110 °, 0 °) (0 °, 125 ° to 136 °, 0 °) (0 °, 149 ° to 159 °, 0 °) (0 °, 165 ° to 175 °, 0 °) The surface acoustic wave device according to claim 11 or 12, wherein the standardized film thickness of said IDT electrode is 0.06 to 0.12. The surface acoustic wave device as claimed in claim 11 or 12, wherein the normalized film thickness of said SiO ₂ layer is 0.25 to 0.3. The surface acoustic wave device according to claim 11 or 12, wherein an upper surface of the IDT electrode and an upper surface of the LiNbO ₃ substrate are coplanar. The method of claim 11 or 12, wherein the groove is surrounded by an inner bottom surface, a pair of inner surfaces connecting the inner bottom surface and the upper surface of the LiNbO ₃ substrate, wherein the inner surface and the upper surface of the LiNbO ₃ substrate made The surface acoustic wave device according to claim 1, wherein the groove angle is in a range of 45 ° to 90 °. The surface acoustic wave device as claimed in claim 16, wherein an inner angle of the groove is in a range of 50 degrees to 80 degrees. The surface acoustic wave according to any one of claims 1 to 8, 11 or 12, wherein the IDT electrode is formed of an adhesion layer made of Al and a metal or alloy having a higher density than Al. Device. The surface acoustic wave device as claimed in any one of claims 1 to 7, wherein the IDT electrode has formed an adhesion layer made of a metal having a higher density than Al. The surface acoustic wave device as claimed in claim 10, wherein an inner angle of the groove is in a range of 50 ° to 80 °.

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