WO2014054580A1 - Elastic surface wave device - Google Patents

Elastic surface wave device Download PDF

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Publication number
WO2014054580A1
WO2014054580A1 PCT/JP2013/076540 JP2013076540W WO2014054580A1 WO 2014054580 A1 WO2014054580 A1 WO 2014054580A1 JP 2013076540 W JP2013076540 W JP 2013076540W WO 2014054580 A1 WO2014054580 A1 WO 2014054580A1
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Prior art keywords
idt electrode
acoustic wave
wave device
groove
surface acoustic
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PCT/JP2013/076540
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French (fr)
Japanese (ja)
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門田　道雄
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株式会社村田製作所
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Priority to JP2014539729A priority Critical patent/JP5757369B2/en
Publication of WO2014054580A1 publication Critical patent/WO2014054580A1/en

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02535—Details of surface acoustic wave devices
    • H03H9/02543—Characteristics of substrate, e.g. cutting angles
    • H03H9/02559—Characteristics of substrate, e.g. cutting angles of lithium niobate or lithium-tantalate substrates
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
    • H03H9/14538—Formation

Definitions

  • the present invention relates to a surface acoustic wave device in which an IDT electrode is formed by embedding a metal in a groove formed on one surface of a LiNbO 3 substrate, and more particularly to a surface acoustic wave device using a Love wave.
  • Patent Document 1 discloses a surface acoustic wave device using a LiTaO 3 substrate or a LiNbO 3 substrate.
  • this surface acoustic wave device grooves are formed on a piezoelectric substrate made of a LiTaO 3 substrate or a LiNbO 3 substrate.
  • An IDT electrode is formed by filling the groove with Al.
  • an SiO 2 film is laminated so as to cover the piezoelectric substrate and the IDT electrode. Thereby, an improvement in temperature characteristics and a high reflection coefficient can be obtained.
  • Patent Document 1 also discloses a surface acoustic wave device in which a groove on the upper surface of a LiNbO 3 substrate is filled with Au.
  • the electromechanical coupling coefficient k 2 and the reflection coefficient change by changing the Euler angle of the LiNbO 3 substrate and the film thickness of the Au film.
  • Patent Document 1 shows that when Au is used instead of Al as described above, an electromechanical coupling coefficient k 2 equal to or higher than Al and a reflection coefficient larger than Al are obtained. It ’s just that. Further, it is only described that an electromechanical coupling coefficient k 2 and a reflection coefficient close to Au can be obtained even for metals such as Cu, Ni, Mo, Ag, Ta, and W. Note that Patent Document 1 does not specifically mention a configuration capable of obtaining a wider specific bandwidth.
  • An object of the present invention is to provide a surface acoustic wave device that can obtain a wider specific bandwidth.
  • the surface acoustic wave device has a LiNbO 3 substrate having a groove formed on the upper surface and an Euler angle in the range of (0 °, 80 ° to 130 °, 0 °).
  • a groove provided on the upper surface of the LiNbO 3 substrate is filled with a metal having a density higher than that of aluminum to form an IDT electrode. A Love wave excited by the IDT electrode is used.
  • the groove extends in the direction in which the electrode finger of the IDT electrode extends, the side surface of the groove in the cross section of the groove is inclined, and the angle between the side surface and the extended surface of the bottom of the groove
  • the tilt angle A is in the range of 56 ° to 84 °, and the duty of the IDT electrode is 0.45 or less.
  • the IDT electrode is made of a material mainly composed of Pt, and the duty is 0.2 or more. In this case, a sufficient specific bandwidth of 20% or more can be obtained using an IDT electrode made of Pt. More preferably, when the wavelength determined by the period of the electrode fingers of the IDT electrode is ⁇ , the thickness of the IDT electrode made of Pt is in the range of 0.06 ⁇ to 0.5 ⁇ .
  • the IDT electrode is made of a material mainly composed of Cu, and the duty is 0.25 or more.
  • the duty is 0.25 or more.
  • the thickness of the IDT electrode made of Cu is in the range of 0.16 ⁇ to 0.5 ⁇ . In this case, the specific bandwidth can be more reliably set to 20% or more.
  • the IDT electrode is made of a material mainly composed of Mo, and the duty is 0.35 or more.
  • Mo the thickness of the IDT electrode made of Mo is in the range of 0.16 ⁇ to 0.3 ⁇ . In this case, the specific bandwidth can be more reliably set to 20% or more.
  • the IDT electrode is made of a material mainly containing Ni, and the duty is 0.4 or more.
  • the duty is 0.4 or more.
  • the thickness of the IDT electrode made of Ni is in the range of 0.2 ⁇ to 0.3 ⁇ . In this case, the specific bandwidth can be more reliably set to 20% or more.
  • the IDT electrode is made of a material mainly composed of Ta, and the duty is 0.3 or more.
  • the duty is 0.3 or more.
  • the thickness of the IDT electrode made of Ta is in the range of 0.11 ⁇ to 0.3 ⁇ . In this case, the specific bandwidth can be more reliably set to 20% or more.
  • the IDT electrode is made of a material mainly composed of W, and the duty is 0.3 or more.
  • a surface acoustic wave device having a wide specific bandwidth can be reliably provided by using W as the IDT electrode. More preferably, when the wavelength determined by the period of the electrode fingers of the IDT electrode is ⁇ , the thickness of the IDT electrode made of W is in the range of 0.08 ⁇ or more and 0.3 ⁇ or less. In this case, the specific bandwidth can be more reliably set to 20% or more.
  • the IDT electrode made of a metal having a density higher than that of aluminum is formed by filling the groove with the metal, and the inclination angle A of the groove is 56 ° to 84 °.
  • the duty of the IDT electrode is 0.45 or less
  • the Euler angle of the LiNbO 3 substrate is in the specific range, so that the specific bandwidth of the surface acoustic wave device can be expanded. It becomes. Accordingly, it is possible to provide a broadband resonator and a bandpass filter.
  • FIG. 1A and FIG. 1B are a schematic plan view of a surface acoustic wave device according to an embodiment of the present invention and a partial surface cross-sectional view showing the main part thereof.
  • Euler in structure IDT electrode composed of Cu is LiNbO 3 SAW devices are formed by filling the Cu in the groove of the upper surface of the substrate to form an IDT electrode composed of Cu film LiNbO 3 substrate It is a figure which shows the relationship between (theta) of an angle, and an electromechanical coupling coefficient.
  • FIG. 3 shows a groove inclination angle A in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on an upper surface of a EuN angle (0 °, 112 °, 0 °) LiNbO 3 substrate with Pt. It is a figure which shows the relationship between the duty of IDT electrode, and specific bandwidth (DELTA) f.
  • FIG. 4 shows the thickness of the Pt film (H / H) in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °).
  • FIG. 5 shows a groove inclination angle A in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a EuN angle (0 °, 112 °, 0 °) LiNbO 3 substrate with Cu. It is a figure which shows the relationship between the duty of IDT electrode, and specific bandwidth (DELTA) f.
  • FIG. 5 shows a groove inclination angle A in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a EuN angle (0 °, 112 °, 0 °) LiNbO 3 substrate with Cu.
  • FIG. 6 shows the thickness of a Cu film (H / H) in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °). It is a figure which shows the relationship between (lambda)), the duty of IDT electrode, and specific bandwidth (DELTA) f.
  • FIG. 7 shows a groove inclination angle A in a surface acoustic wave device in which an IDT electrode is formed by filling Mo in a groove on the upper surface of a EuN angle (0 °, 112 °, 0 °) LiNbO 3 substrate.
  • FIG. 8 shows the thickness of the Mo film (H / H) in a surface acoustic wave device in which an IDT electrode is formed by filling Mo in a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °). It is a figure which shows the relationship between (lambda)), the duty of IDT electrode, and specific bandwidth (DELTA) f.
  • FIG. 9 shows a groove inclination angle A in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °). It is a figure which shows the relationship between the duty of IDT electrode, and specific bandwidth (DELTA) f.
  • FIG. 10 shows the thickness of the Ni film (H / H) in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °).
  • FIG. 11 shows an inclination angle A of a groove in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °); It is a figure which shows the relationship between the duty of IDT electrode, and specific bandwidth (DELTA) f.
  • FIG. 11 shows an inclination angle A of a groove in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °); It is a figure which shows the relationship between the duty of IDT electrode, and specific bandwidth (DELTA) f.
  • FIG. 12 shows the thickness (H / H) of a Ta film in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °). It is a figure which shows the relationship between (lambda)), the duty of IDT electrode, and specific bandwidth (DELTA) f.
  • FIG. 13 shows a groove inclination angle A in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °), It is a figure which shows the relationship between the duty of IDT electrode, and specific bandwidth (DELTA) f.
  • FIG. 14 shows the thickness of a W film (H / H) in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °). It is a figure which shows the relationship between (lambda)), the duty of IDT electrode, and specific bandwidth (DELTA) f.
  • a surface acoustic wave device 11 has a LiNbO 3 substrate 1.
  • an IDT electrode 3 and reflectors 12 and 13 disposed on both sides of the IDT electrode 3 in the surface wave propagation direction are formed on a LiNbO 3 substrate 1.
  • a plurality of grooves 1 b are formed on the upper surface 1 a of the LiNbO 3 substrate 1.
  • the groove 1b corresponds to an electrode finger constituent part of the IDT electrode.
  • the groove 1b is filled with a metal having a higher density than Al to form the IDT electrode 3.
  • the reflectors 12 and 13 shown in FIG. 1A are also formed by filling a plurality of grooves with a metal having a density higher than that of Al.
  • the upper surface of the metal filled in the groove 1b and the upper surface 1a of the LiNbO 3 substrate 1 are substantially flush with each other.
  • channel 1b are made into the inclined surface.
  • the electrode fingers of the IDT electrode 3 extend in a direction orthogonal to the elastic wave propagation direction.
  • FIG. 1B a portion corresponding to the cross section of the electrode finger is shown.
  • the side surfaces 1b1 and 1b2 are inclined from the direction orthogonal to the bottom surface 1b3 of the groove 1b. More specifically, the inclination angle A shown in FIG. 1 (b) is in the range of 56 ° to 84 °.
  • the inclination angle A is the angle formed between the side surface 1b1 and the extended portion 1b4 of the bottom surface 1b3, in other words, the angle formed between the side surface 1b1 and the electrode finger upper surface 3a, taking the side surface 1b1 as an example.
  • the duty of the IDT electrode 3 is set to 0.45 or less.
  • the duty is a value represented by a ratio between the upper surface of the groove 1b, that is, the width of the electrode finger upper surface 3a and the value obtained by adding the distance between the electrode finger upper surface 3a and the adjacent electrode finger.
  • the Euler angles of the LiNbO 3 substrate 1 are (0 °, 80 ° to 130 °, 0 °). In the present embodiment, since the above configuration is provided, a large specific bandwidth ⁇ f is obtained. This will be described more specifically below.
  • Euler angles of LiNbO 3 (0 °, ⁇ , 0 °) is a diagram showing a theta of, the relationship between the electromechanical coupling factor k 2.
  • the IDT electrode is made of Cu and has a thickness of 0.1 ⁇ , 0.16 ⁇ , 0.2 ⁇ , or 0.5 ⁇ .
  • ⁇ is the wavelength of the propagating elastic wave.
  • the solid line B in FIG. 2 shows the electromechanical coupling coefficient k 2 of the Love wave in the surface acoustic wave device 11 of the above embodiment when the thickness of Cu is 0.1 [lambda], the thickness of the solid line C is Cu 0.1 [lambda] It shows the change in electromechanical coupling coefficient k 2 of the Rayleigh wave in the case where.
  • a broken line D indicates a Love wave in a structure in which an IDT electrode made of a Cu film having a thickness of 0.1 ⁇ is formed on the upper surface without forming a groove on the upper surface of LiNbO 3 when the thickness of Cu is 0.1 ⁇ . shows the change in electromechanical coupling coefficient k 2, the broken line E shows the change of the electromechanical coupling coefficient k 2 of the Rayleigh wave.
  • the two-dot chain line F, the solid line G, and the one-dot chain line H in FIG. 2 indicate the rub in the surface acoustic wave device 11 of the above embodiment when the Cu thickness is 0.16 ⁇ , 0.2 ⁇ , or 0.5 ⁇ , respectively. It shows the change in electromechanical coupling coefficient k 2 of the waves.
  • the electromechanical coupling coefficient k 2 of the Love wave is It can be seen that it can be increased to 0.3 or more. Therefore, it can be seen that the specific bandwidth can be effectively increased.
  • the Euler angle ⁇ is 80 ° even when another metal having a higher density than Al such as Pt and Au is used as the electrode material. If it is within the range of ⁇ 130 °, it is possible to effectively increase the electromechanical coupling coefficient k 2 of the Love wave.
  • the electrode material is Pt and Cu will be described separately.
  • Pt (In the case of IDT electrode made of Pt) Pt was used as the electrode material.
  • the electrode material only needs to be mainly composed of Pt.
  • Pt is mainly composed of the value of Pt (density ⁇ electrode thickness) and the whole IDT electrode composed of a plurality of types of electrode materials.
  • the ratio of the density of the electrode and the sum of the products of the thicknesses of the electrodes exceeds 0.5.
  • the sum of the product of the density of the entire IDT electrode and the electrode thickness is a value represented by the following equation.
  • ⁇ density
  • T electrode thickness
  • n the number of electrode layers constituting the IDT electrode.
  • the Euler angles of the LiNbO 3 substrate were (0 °, 112 °, 0 °).
  • Various surface acoustic wave devices 11 were manufactured by changing the inclination angle A in the groove 1b in various ways, except that the thickness of the IDT electrode made of Pt was 0.1 ⁇ .
  • FIG. 3 shows the relationship between the groove inclination angle A, the duty, and the love wave specific bandwidth ⁇ f.
  • the specific bandwidth ⁇ f is a value represented by (fa ⁇ fr) / fr where the resonance frequency in the surface acoustic wave device 11 is fr and the antiresonance frequency is fa.
  • the specific bandwidth ⁇ f can be 0.20 or more.
  • FIG. 4 shows the relationship between the Pt thickness (H / ⁇ ) and the specific bandwidth ⁇ f when the Pt film thickness, that is, the groove thickness in the surface acoustic wave device 11 is changed.
  • the inclination angle A of the groove was 78 °.
  • the duty when the duty is in the range of 0.2 to 0.45, a Love wave is excited and a large specific bandwidth ⁇ f is obtained. In this case, when the duty is less than 0.2, the Love wave excitation state is unstable. Therefore, when an IDT electrode made of Pt is used, the duty is desirably 0.2 or more.
  • the thickness H / ⁇ of the Pt film is preferably 0.06 ⁇ or more and 0.5 ⁇ or less within the duty range of 0.2 to 0.45. . Accordingly, it can be seen that the specific bandwidth ⁇ f can be surely set to 0.20 or more, that is, 20% or more. Therefore, the thickness of the Pt film is preferably 0.06 ⁇ or more and 0.5 ⁇ or less. From FIG. 4, the thickness of the Pt film is more preferably 0.08 ⁇ or more.
  • FIG. 5 shows the relationship among the groove inclination angle A, the duty, and the specific bandwidth ⁇ f.
  • the specific bandwidth ⁇ f is a value represented by (fa ⁇ fr) / fr where the resonance frequency in the surface acoustic wave device 11 is fr and the antiresonance frequency is fa.
  • the specific bandwidth ⁇ f can be 0.20 or more.
  • FIG. 6 shows the relationship between the Cu thickness (H / ⁇ ) and the specific bandwidth ⁇ f when the Cu film thickness, that is, the groove thickness in the surface acoustic wave device 11 is changed.
  • the inclination angle A of the groove was 78 °.
  • the duty when the duty is in the range of 0.25 to 0.45, a Love wave is excited and a large specific bandwidth ⁇ f is obtained. More preferably, if the duty is 0.4 or less, it can be seen that ⁇ f can be 20% or more. In this case, when the duty is less than 0.25, the Love wave excitation state is unstable. Therefore, when an IDT electrode made of Cu is used, the duty is desirably 0.25 or more.
  • the thickness H / ⁇ of the Cu film is preferably 0.16 ⁇ or more and 0.5 ⁇ or less within the range of the duty of 0.25 to 0.45. . Accordingly, it can be seen that the specific bandwidth ⁇ f can be surely set to 0.20 or more, that is, 20% or more. Therefore, the thickness of the Cu film is desirably 0.16 ⁇ or more and 0.5 ⁇ or less. Further, more preferably 0.17 ⁇ or more from FIG. It can also be seen that if the duty is in the range of 0.25 to 0.4 and the thickness of the Cu film is 0.16 ⁇ to 0.5 ⁇ , ⁇ f can be 20% or more.
  • FIG. 7 shows the relationship between the groove inclination angle A, the duty, and the specific bandwidth ⁇ f.
  • the specific bandwidth ⁇ f is a value represented by (fa ⁇ fr) / fr where the resonance frequency in the surface acoustic wave device 11 is fr and the antiresonance frequency is fa.
  • the specific bandwidth ⁇ f can be 0.20 or more when the inclination angle A is in the range of 56 ° to 84 ° and the duty is 0.45 or less.
  • FIG. 8 shows the relationship between the Mo thickness (H / ⁇ ) and the specific bandwidth ⁇ f when the Mo film thickness, that is, the groove thickness in the surface acoustic wave device 11 is changed.
  • the inclination angle A of the groove was 78 °.
  • the thickness H / ⁇ of the Mo film is preferably 0.16 ⁇ or more and 0.3 ⁇ or less within a duty range of 0.35 to 0.45. Accordingly, it can be seen that the specific bandwidth ⁇ f can be reliably set to 0.23 or more, that is, 23% or more. Therefore, the thickness of the Mo film is desirably 0.16 ⁇ or more and 0.3 ⁇ or less.
  • FIG. 9 shows the relationship among the groove inclination angle A, the duty, and the specific bandwidth ⁇ f.
  • the specific bandwidth ⁇ f is a value represented by (fa ⁇ fr) / fr where the resonance frequency in the surface acoustic wave device 11 is fr and the antiresonance frequency is fa.
  • the specific bandwidth ⁇ f can be 0.22 or more.
  • FIG. 10 shows the relationship between the Ni thickness (H / ⁇ ) and the specific bandwidth ⁇ f when the Ni film thickness, that is, the groove thickness in the surface acoustic wave device 11 is changed.
  • the inclination angle A of the groove was 78 °.
  • the thickness H / ⁇ of the Ni film is preferably 0.2 ⁇ or more and 0.3 ⁇ or less within the duty range of 0.4 to 0.45. Accordingly, it can be seen that the specific bandwidth ⁇ f can be surely set to 0.22 or more, that is, 22% or more. Therefore, the thickness of the Ni film is preferably 0.2 ⁇ or more and 0.3 ⁇ or less.
  • FIG. 11 shows the relationship between the groove inclination angle A, the duty, and the specific bandwidth ⁇ f.
  • the specific bandwidth ⁇ f is a value represented by (fa ⁇ fr) / fr where the resonance frequency in the surface acoustic wave device 11 is fr and the antiresonance frequency is fa.
  • the specific bandwidth ⁇ f can be 0.23 or more.
  • FIG. 12 shows the relationship between the Ta thickness (H / ⁇ ) and the specific bandwidth ⁇ f when the Ta film thickness, that is, the groove thickness in the surface acoustic wave device 11 is changed.
  • the inclination angle A of the groove was 78 °.
  • ⁇ f can be 23.5% or more when the duty is 0.4 or less.
  • the duty is desirably 0.3 or more.
  • the thickness H / ⁇ of the Ta film is preferably 0.11 ⁇ or more and 0.3 ⁇ or less in the range of duty of 0.3 to 0.45. Accordingly, it can be seen that the specific bandwidth ⁇ f can be reliably set to 0.21 or more, that is, 21% or more. Therefore, the thickness of the Ta film is preferably 0.11 ⁇ or more and 0.3 ⁇ or less.
  • FIG. 13 shows the relationship among the groove inclination angle A, the duty, and the specific bandwidth ⁇ f.
  • the specific bandwidth ⁇ f is a value represented by (fa ⁇ fr) / fr where the resonance frequency in the surface acoustic wave device 11 is fr and the antiresonance frequency is fa.
  • the specific bandwidth ⁇ f can be 0.23 or more.
  • FIG. 14 shows the relationship between the W thickness (H / ⁇ ) and the specific bandwidth ⁇ f when the thickness of the W in the surface acoustic wave device 11, that is, the thickness of the groove is changed.
  • the inclination angle A of the groove was 78 °.
  • the thickness H / ⁇ of the W film is preferably 0.08 ⁇ or more and 0.3 ⁇ or less within a duty range of 0.3 to 0.45. Accordingly, it can be seen that the specific bandwidth ⁇ f can be reliably set to 0.23 or more, that is, 23% or more. Therefore, the thickness of the W film is desirably 0.08 ⁇ or more and 0.3 ⁇ or less.
  • the IDT electrode is mainly composed of Pt, Cu, Mo, Ni, Ta or W.
  • the IDT electrode is composed of a metal having a density higher than that of Al. What is necessary is just to be carried out and it is not limited to said each metal.
  • the one-port surface acoustic wave resonator has been described.
  • the present invention can also be applied to other surface acoustic wave devices such as a resonator type surface acoustic wave filter. it can. Accordingly, the number and arrangement of the IDT electrodes can be appropriately modified according to the function of the surface acoustic wave device.

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)

Abstract

Provided is an elastic surface wave device capable of achieving a wider band. An elastic surface wave device (11), wherein an IDT electrode (3) is formed by filling a groove (1b) in the upper surface (1a) of a LiNbO3 substrate (1) having the groove (1b) formed in the upper surface (1a) and having Euler angles in the range of (0°, 80°-130°, 0°) with metal having a higher density than that of aluminum, the groove (1b) extends in the direction in which the electrode finger of the IDT electrode (3) extends, side surfaces (1b1, 1b2) of the groove (1b) in the cross section of the groove are inclined, an inclination angle (A) that is the angle which the side surface (1b1, 1b2) forms with the extended surface (1b4) of the bottom (1b3) of the groove is in the range of 56°-84°, and the duty of the IDT electrode (3) is 0.45 or less.

Description

弾性表面波装置Surface acoustic wave device
　本発明は、ＬｉＮｂＯ３基板の一方面に形成された溝に金属を埋め込むことによりＩＤＴ電極が形成されている弾性表面波装置に関し、より詳細には、ラブ波を利用した弾性表面波装置に関する。 The present invention relates to a surface acoustic wave device in which an IDT electrode is formed by embedding a metal in a groove formed on one surface of a LiNbO 3 substrate, and more particularly to a surface acoustic wave device using a Love wave.
　従来、移動体通信機のバンドパスフィルタとして弾性表面波装置が広く用いられている。下記の特許文献１には、ＬｉＴａＯ３基板またはＬｉＮｂＯ３基板を用いた弾性表面波装置が開示されている。この弾性表面波装置では、ＬｉＴａＯ３基板やＬｉＮｂＯ３基板からなる圧電基板上に溝が形成されている。この溝にＡｌを充填することによりＩＤＴ電極が形成されている。さらに、圧電基板及びＩＤＴ電極を覆うように、ＳｉＯ２膜が積層されている。それによって、温度特性の改善と、高い反射係数とを得ることができる。 Conventionally, surface acoustic wave devices have been widely used as bandpass filters for mobile communication devices. The following Patent Document 1 discloses a surface acoustic wave device using a LiTaO 3 substrate or a LiNbO 3 substrate. In this surface acoustic wave device, grooves are formed on a piezoelectric substrate made of a LiTaO 3 substrate or a LiNbO 3 substrate. An IDT electrode is formed by filling the groove with Al. Further, an SiO 2 film is laminated so as to cover the piezoelectric substrate and the IDT electrode. Thereby, an improvement in temperature characteristics and a high reflection coefficient can be obtained.
　また、特許文献１では、ＬｉＮｂＯ３基板の上面の溝にＡｕを充填してなる弾性表面波装置も開示されている。ここでは、ＬｉＮｂＯ３基板のオイラー角と、Ａｕ膜の膜厚とを変化させることにより、電気機械結合係数ｋ２及び反射係数が変化することが示されている。 Patent Document 1 also discloses a surface acoustic wave device in which a groove on the upper surface of a LiNbO 3 substrate is filled with Au. Here, it is shown that the electromechanical coupling coefficient k 2 and the reflection coefficient change by changing the Euler angle of the LiNbO 3 substrate and the film thickness of the Au film.
ＷＯ２００６／０１１４１７WO2006 / 011417
　しかしながら、特許文献１では、上記のようにＡｌに代えてＡｕを用いた場合、Ａｌと同等もしくはそれ以上の電気機械結合係数ｋ２及びＡｌよりも大きな反射係数が得られている旨が示されているにすぎない。また、Ｃｕ、Ｎｉ、Ｍｏ、Ａｇ、Ｔａ、Ｗなどの金属においても、Ａｕに近い電気機械結合係数ｋ２と反射係数が得られる旨が述べられているにすぎない。なお、特許文献１には、より広い比帯域幅を得ることができる構成については具体的に言及されていない。 However, Patent Document 1 shows that when Au is used instead of Al as described above, an electromechanical coupling coefficient k 2 equal to or higher than Al and a reflection coefficient larger than Al are obtained. It ’s just that. Further, it is only described that an electromechanical coupling coefficient k 2 and a reflection coefficient close to Au can be obtained even for metals such as Cu, Ni, Mo, Ag, Ta, and W. Note that Patent Document 1 does not specifically mention a configuration capable of obtaining a wider specific bandwidth.
　本発明の目的は、より一層広い比帯域幅を得ることができる弾性表面波装置を提供することにある。 An object of the present invention is to provide a surface acoustic wave device that can obtain a wider specific bandwidth.
　本発明に係る弾性表面波装置は、上面に溝が形成されており、かつオイラー角が（０°，８０°～１３０°，０°）の範囲にあるＬｉＮｂＯ３基板を有する。ＬｉＮｂＯ３基板の上面に設けられている溝に、アルミニウムよりも密度が大きい金属が充填されて、ＩＤＴ電極が形成されている。上記ＩＤＴ電極により励振されたラブ波が利用される。本発明では、前記溝が前記ＩＤＴ電極の電極指の延びる方向に延びており、該溝の横断面における溝の側面が傾斜しており、該側面の前記溝の底部の延長面とのなす角度である傾斜角度Ａが５６°～８４°の範囲内にあり、前記ＩＤＴ電極のデューティが０．４５以下である。 The surface acoustic wave device according to the present invention has a LiNbO 3 substrate having a groove formed on the upper surface and an Euler angle in the range of (0 °, 80 ° to 130 °, 0 °). A groove provided on the upper surface of the LiNbO 3 substrate is filled with a metal having a density higher than that of aluminum to form an IDT electrode. A Love wave excited by the IDT electrode is used. In the present invention, the groove extends in the direction in which the electrode finger of the IDT electrode extends, the side surface of the groove in the cross section of the groove is inclined, and the angle between the side surface and the extended surface of the bottom of the groove The tilt angle A is in the range of 56 ° to 84 °, and the duty of the IDT electrode is 0.45 or less.
　本発明に係る弾性表面波装置のある特定の局面では、前記ＩＤＴ電極がＰｔを主体とする材料からなり、前記デューティが０．２以上である。この場合には、ＰｔからなるＩＤＴ電極を用い、２０％以上の充分な比帯域幅を得ることができる。より好ましくは、前記ＩＤＴ電極の電極指の周期により定まる波長をλとしたときに、ＰｔからなるＩＤＴ電極の厚みが０．０６λ以上、０．５λ以下の範囲とされる。 In a specific aspect of the surface acoustic wave device according to the present invention, the IDT electrode is made of a material mainly composed of Pt, and the duty is 0.2 or more. In this case, a sufficient specific bandwidth of 20% or more can be obtained using an IDT electrode made of Pt. More preferably, when the wavelength determined by the period of the electrode fingers of the IDT electrode is λ, the thickness of the IDT electrode made of Pt is in the range of 0.06λ to 0.5λ.
　本発明に係る弾性表面波装置のさらに他の特定の局面では、前記ＩＤＴ電極がＣｕを主体とする材料からなり、前記デューティが０．２５以上である。この場合には、ＩＤＴ電極としてＣｕを用い、比帯域幅が広い弾性表面波装置を確実に提供することができる。より好ましくは、前記ＩＤＴ電極の電極指の周期により定まる波長をλとしたときに、ＣｕからなるＩＤＴ電極の厚みが０．１６λ以上、０．５λ以下の範囲にある。この場合には、比帯域幅をより一層確実に２０％以上とすることができる。 In still another specific aspect of the surface acoustic wave device according to the present invention, the IDT electrode is made of a material mainly composed of Cu, and the duty is 0.25 or more. In this case, it is possible to reliably provide a surface acoustic wave device having a wide specific bandwidth using Cu as the IDT electrode. More preferably, when the wavelength determined by the period of the electrode fingers of the IDT electrode is λ, the thickness of the IDT electrode made of Cu is in the range of 0.16λ to 0.5λ. In this case, the specific bandwidth can be more reliably set to 20% or more.
　本発明に係る弾性表面波装置のさらに他の特定の局面では、前記ＩＤＴ電極がＭｏを主体とする材料からなり、前記デューティが０．３５以上である。この場合には、ＩＤＴ電極としてＭｏを用い、比帯域幅が広い弾性表面波装置を確実に提供することができる。より好ましくは、前記ＩＤＴ電極の電極指の周期により定まる波長をλとしたときに、ＭｏからなるＩＤＴ電極の厚みが０．１６λ以上、０．３λ以下の範囲にある。この場合には、比帯域幅をより一層確実に２０％以上とすることができる。 In still another specific aspect of the surface acoustic wave device according to the present invention, the IDT electrode is made of a material mainly composed of Mo, and the duty is 0.35 or more. In this case, it is possible to reliably provide a surface acoustic wave device having a wide specific bandwidth by using Mo as the IDT electrode. More preferably, when the wavelength determined by the period of the electrode fingers of the IDT electrode is λ, the thickness of the IDT electrode made of Mo is in the range of 0.16λ to 0.3λ. In this case, the specific bandwidth can be more reliably set to 20% or more.
　本発明に係る弾性表面波装置のさらに他の特定の局面では、前記ＩＤＴ電極がＮｉを主体とする材料からなり、前記デューティが０．４以上である。この場合には、ＩＤＴ電極としてＮｉを用い、比帯域幅が広い弾性表面波装置を確実に提供することができる。より好ましくは、前記ＩＤＴ電極の電極指の周期により定まる波長をλとしたときに、ＮｉからなるＩＤＴ電極の厚みが０．２λ以上、０．３λ以下の範囲にある。この場合には、比帯域幅をより一層確実に２０％以上とすることができる。 In still another specific aspect of the surface acoustic wave device according to the present invention, the IDT electrode is made of a material mainly containing Ni, and the duty is 0.4 or more. In this case, it is possible to reliably provide a surface acoustic wave device having a wide specific bandwidth using Ni as the IDT electrode. More preferably, when the wavelength determined by the period of the electrode fingers of the IDT electrode is λ, the thickness of the IDT electrode made of Ni is in the range of 0.2λ to 0.3λ. In this case, the specific bandwidth can be more reliably set to 20% or more.
　本発明に係る弾性表面波装置のさらに他の特定の局面では、前記ＩＤＴ電極がＴａを主体とする材料からなり、前記デューティが０．３以上である。この場合には、ＩＤＴ電極としてＴａを用い、比帯域幅が広い弾性表面波装置を確実に提供することができる。より好ましくは、前記ＩＤＴ電極の電極指の周期により定まる波長をλとしたときに、ＴａからなるＩＤＴ電極の厚みが０．１１λ以上、０．３λ以下の範囲にある。この場合には、比帯域幅をより一層確実に２０％以上とすることができる。 In still another specific aspect of the surface acoustic wave device according to the present invention, the IDT electrode is made of a material mainly composed of Ta, and the duty is 0.3 or more. In this case, it is possible to reliably provide a surface acoustic wave device having a wide specific bandwidth by using Ta as the IDT electrode. More preferably, when the wavelength determined by the period of the electrode fingers of the IDT electrode is λ, the thickness of the IDT electrode made of Ta is in the range of 0.11λ to 0.3λ. In this case, the specific bandwidth can be more reliably set to 20% or more.
　本発明に係る弾性表面波装置のさらに他の特定の局面では、前記ＩＤＴ電極がＷを主体とする材料からなり、前記デューティが０．３以上である。この場合には、ＩＤＴ電極としてＷを用い、比帯域幅が広い弾性表面波装置を確実に提供することができる。より好ましくは、前記ＩＤＴ電極の電極指の周期により定まる波長をλとしたときに、ＷからなるＩＤＴ電極の厚みが０．０８λ以上、０．３λ以下の範囲にある。この場合には、比帯域幅をより一層確実に２０％以上とすることができる。 In still another specific aspect of the surface acoustic wave device according to the present invention, the IDT electrode is made of a material mainly composed of W, and the duty is 0.3 or more. In this case, a surface acoustic wave device having a wide specific bandwidth can be reliably provided by using W as the IDT electrode. More preferably, when the wavelength determined by the period of the electrode fingers of the IDT electrode is λ, the thickness of the IDT electrode made of W is in the range of 0.08λ or more and 0.3λ or less. In this case, the specific bandwidth can be more reliably set to 20% or more.
　本発明に係る弾性表面波装置によれば、アルミニウムよりも密度が大きい金属からなるＩＤＴ電極が溝に該金属を充填することにより形成されており、該溝の傾斜角度Ａが５６°～８４°の範囲にあり、ＩＤＴ電極のデューティが０．４５以下とされており、さらにＬｉＮｂＯ３基板のオイラー角が上記特定の範囲とされているため、弾性表面波装置の比帯域幅を広げることが可能となる。従って、広帯域の共振子やバンドパスフィルタを提供することができる。 According to the surface acoustic wave device of the present invention, the IDT electrode made of a metal having a density higher than that of aluminum is formed by filling the groove with the metal, and the inclination angle A of the groove is 56 ° to 84 °. In this range, the duty of the IDT electrode is 0.45 or less, and the Euler angle of the LiNbO 3 substrate is in the specific range, so that the specific bandwidth of the surface acoustic wave device can be expanded. It becomes. Accordingly, it is possible to provide a broadband resonator and a bandpass filter.
図１（ａ）及び図１（ｂ）は本発明の一実施形態に係る弾性表面波装置の模式的平面図及びその要部を示す部分表面断面図である。FIG. 1A and FIG. 1B are a schematic plan view of a surface acoustic wave device according to an embodiment of the present invention and a partial surface cross-sectional view showing the main part thereof. 図２は、ＣｕからなるＩＤＴ電極がＬｉＮｂＯ３基板の上面の溝にＣｕを充填することにより形成されている弾性表面波装置、ＬｉＮｂＯ３基板上にＣｕ膜からなるＩＤＴ電極を形成した構造におけるオイラー角のθと、電気機械結合係数との関係を示す図である。2, Euler in structure IDT electrode composed of Cu is LiNbO 3 SAW devices are formed by filling the Cu in the groove of the upper surface of the substrate to form an IDT electrode composed of Cu film LiNbO 3 substrate It is a figure which shows the relationship between (theta) of an angle, and an electromechanical coupling coefficient. 図３は、オイラー角（０°，１１２°，０°）のＬｉＮｂＯ３基板の上面の溝にＰｔを充填してＩＤＴ電極が形成されている弾性表面波装置における、溝の傾斜角度Ａと、ＩＤＴ電極のデューティと、比帯域幅Δｆとの関係を示す図である。FIG. 3 shows a groove inclination angle A in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on an upper surface of a EuN angle (0 °, 112 °, 0 °) LiNbO 3 substrate with Pt. It is a figure which shows the relationship between the duty of IDT electrode, and specific bandwidth (DELTA) f. 図４は、オイラー角（０°，１１２°，０°）のＬｉＮｂＯ３基板の上面の溝にＰｔを充填してＩＤＴ電極が形成されている弾性表面波装置における、Ｐｔ膜の厚み（Ｈ／λ）と、ＩＤＴ電極のデューティと、比帯域幅Δｆとの関係を示す図である。FIG. 4 shows the thickness of the Pt film (H / H) in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °). It is a figure which shows the relationship between (lambda)), the duty of IDT electrode, and specific bandwidth (DELTA) f. 図５は、オイラー角（０°，１１２°，０°）のＬｉＮｂＯ３基板の上面の溝にＣｕを充填してＩＤＴ電極が形成されている弾性表面波装置における、溝の傾斜角度Ａと、ＩＤＴ電極のデューティと、比帯域幅Δｆとの関係を示す図である。FIG. 5 shows a groove inclination angle A in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a EuN angle (0 °, 112 °, 0 °) LiNbO 3 substrate with Cu. It is a figure which shows the relationship between the duty of IDT electrode, and specific bandwidth (DELTA) f. 図６は、オイラー角（０°，１１２°，０°）のＬｉＮｂＯ３基板の上面の溝にＣｕを充填してＩＤＴ電極が形成されている弾性表面波装置における、Ｃｕ膜の厚み（Ｈ／λ）と、ＩＤＴ電極のデューティと、比帯域幅Δｆとの関係を示す図である。FIG. 6 shows the thickness of a Cu film (H / H) in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °). It is a figure which shows the relationship between (lambda)), the duty of IDT electrode, and specific bandwidth (DELTA) f. 図７は、オイラー角（０°，１１２°，０°）のＬｉＮｂＯ３基板の上面の溝にＭｏを充填してＩＤＴ電極が形成されている弾性表面波装置における、溝の傾斜角度Ａと、ＩＤＴ電極のデューティと、比帯域幅Δｆとの関係を示す図である。FIG. 7 shows a groove inclination angle A in a surface acoustic wave device in which an IDT electrode is formed by filling Mo in a groove on the upper surface of a EuN angle (0 °, 112 °, 0 °) LiNbO 3 substrate. It is a figure which shows the relationship between the duty of IDT electrode, and specific bandwidth (DELTA) f. 図８は、オイラー角（０°，１１２°，０°）のＬｉＮｂＯ３基板の上面の溝にＭｏを充填してＩＤＴ電極が形成されている弾性表面波装置における、Ｍｏ膜の厚み（Ｈ／λ）と、ＩＤＴ電極のデューティと、比帯域幅Δｆとの関係を示す図である。FIG. 8 shows the thickness of the Mo film (H / H) in a surface acoustic wave device in which an IDT electrode is formed by filling Mo in a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °). It is a figure which shows the relationship between (lambda)), the duty of IDT electrode, and specific bandwidth (DELTA) f. 図９は、オイラー角（０°，１１２°，０°）のＬｉＮｂＯ３基板の上面の溝にＮｉを充填してＩＤＴ電極が形成されている弾性表面波装置における、溝の傾斜角度Ａと、ＩＤＴ電極のデューティと、比帯域幅Δｆとの関係を示す図である。FIG. 9 shows a groove inclination angle A in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °). It is a figure which shows the relationship between the duty of IDT electrode, and specific bandwidth (DELTA) f. 図１０は、オイラー角（０°，１１２°，０°）のＬｉＮｂＯ３基板の上面の溝にＮｉを充填してＩＤＴ電極が形成されている弾性表面波装置における、Ｎｉ膜の厚み（Ｈ／λ）と、ＩＤＴ電極のデューティと、比帯域幅Δｆとの関係を示す図である。FIG. 10 shows the thickness of the Ni film (H / H) in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °). It is a figure which shows the relationship between (lambda)), the duty of IDT electrode, and specific bandwidth (DELTA) f. 図１１は、オイラー角（０°，１１２°，０°）のＬｉＮｂＯ３基板の上面の溝にＴａを充填してＩＤＴ電極が形成されている弾性表面波装置における、溝の傾斜角度Ａと、ＩＤＴ電極のデューティと、比帯域幅Δｆとの関係を示す図である。FIG. 11 shows an inclination angle A of a groove in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °); It is a figure which shows the relationship between the duty of IDT electrode, and specific bandwidth (DELTA) f. 図１２は、オイラー角（０°，１１２°，０°）のＬｉＮｂＯ３基板の上面の溝にＴａを充填してＩＤＴ電極が形成されている弾性表面波装置における、Ｔａ膜の厚み（Ｈ／λ）と、ＩＤＴ電極のデューティと、比帯域幅Δｆとの関係を示す図である。FIG. 12 shows the thickness (H / H) of a Ta film in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °). It is a figure which shows the relationship between (lambda)), the duty of IDT electrode, and specific bandwidth (DELTA) f. 図１３は、オイラー角（０°，１１２°，０°）のＬｉＮｂＯ３基板の上面の溝にＷを充填してＩＤＴ電極が形成されている弾性表面波装置における、溝の傾斜角度Ａと、ＩＤＴ電極のデューティと、比帯域幅Δｆとの関係を示す図である。FIG. 13 shows a groove inclination angle A in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °), It is a figure which shows the relationship between the duty of IDT electrode, and specific bandwidth (DELTA) f. 図１４は、オイラー角（０°，１１２°，０°）のＬｉＮｂＯ３基板の上面の溝にＷを充填してＩＤＴ電極が形成されている弾性表面波装置における、Ｗ膜の厚み（Ｈ／λ）と、ＩＤＴ電極のデューティと、比帯域幅Δｆとの関係を示す図である。FIG. 14 shows the thickness of a W film (H / H) in a surface acoustic wave device in which an IDT electrode is formed by filling a groove on the upper surface of a LiNbO 3 substrate with Euler angles (0 °, 112 °, 0 °). It is a figure which shows the relationship between (lambda)), the duty of IDT electrode, and specific bandwidth (DELTA) f.
　以下、図面を参照しつつ、本発明の具体的な実施形態を説明することにより、本発明を明らかにする。 Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.
　図１（ａ）に示すように、本発明の一実施形態に係る弾性表面波装置１１は、ＬｉＮｂＯ３基板１を有する。図１（ａ）に示すように、ＬｉＮｂＯ３基板１上に、ＩＤＴ電極３と、ＩＤＴ電極３の表面波伝搬方向両側に配置された反射器１２，１３とが形成されている。図１（ｂ）に示すように、ＬｉＮｂＯ３基板１の上面１ａに複数本の溝１ｂが形成されている。この溝１ｂは、ＩＤＴ電極の電極指構成部分に相当する。溝１ｂに、Ａｌよりも高密度の金属が充填されて、ＩＤＴ電極３が形成されている。図１（ａ）に示した反射器１２，１３も、同様に、複数本の溝にＡｌよりも密度が大きい金属を充填することにより形成されている。 As shown in FIG. 1A, a surface acoustic wave device 11 according to an embodiment of the present invention has a LiNbO 3 substrate 1. As shown in FIG. 1A, an IDT electrode 3 and reflectors 12 and 13 disposed on both sides of the IDT electrode 3 in the surface wave propagation direction are formed on a LiNbO 3 substrate 1. As shown in FIG. 1B, a plurality of grooves 1 b are formed on the upper surface 1 a of the LiNbO 3 substrate 1. The groove 1b corresponds to an electrode finger constituent part of the IDT electrode. The groove 1b is filled with a metal having a higher density than Al to form the IDT electrode 3. Similarly, the reflectors 12 and 13 shown in FIG. 1A are also formed by filling a plurality of grooves with a metal having a density higher than that of Al.
　なお、図１（ｂ）に示すように、上記溝１ｂに充填されている金属の上面と、ＬｉＮｂＯ３基板１の上面１ａとはほぼ面一とされている。 As shown in FIG. 1B, the upper surface of the metal filled in the groove 1b and the upper surface 1a of the LiNbO 3 substrate 1 are substantially flush with each other.
　また、図１（ｂ）に示すように、溝１ｂの側面１ｂ１，１ｂ２は、傾斜面とされている。ＩＤＴ電極３の電極指は、弾性波伝搬方向と直交する方向に延びている。図１（ｂ）では、この電極指の横断面に相当する部分が示されている。側面１ｂ１，１ｂ２は、溝１ｂの底面１ｂ３に対して直交する方向から傾斜されている。より具体的には、図１（ｂ）に示す傾斜角度Ａが、５６°～８４°の範囲内とされている。なお、傾斜角度Ａとは、上記側面１ｂ１を例にとると、側面１ｂ１と上記底面１ｂ３の延長部分１ｂ４とのなす角度、言い換えれば側面１ｂ１と電極指上面３ａとのなす角度である。また、後述するように、ＩＤＴ電極３のデューティは０．４５以下とされている。なお、デューティとは、溝１ｂの上面、すなわち電極指上面３ａの幅と、電極指上面３ａと隣接する電極指との間隔を足し合わせた値との比で表される値である。さらに、上記ＬｉＮｂＯ３基板１のオイラー角は、（０°，８０°～１３０°，０°）とされている。本実施形態では、上記構成を備えるため、大きな比帯域幅Δｆが得られる。これを、以下においてより具体的に説明する。 Moreover, as shown in FIG.1 (b), the side surfaces 1b1 and 1b2 of the groove | channel 1b are made into the inclined surface. The electrode fingers of the IDT electrode 3 extend in a direction orthogonal to the elastic wave propagation direction. In FIG. 1B, a portion corresponding to the cross section of the electrode finger is shown. The side surfaces 1b1 and 1b2 are inclined from the direction orthogonal to the bottom surface 1b3 of the groove 1b. More specifically, the inclination angle A shown in FIG. 1 (b) is in the range of 56 ° to 84 °. Note that the inclination angle A is the angle formed between the side surface 1b1 and the extended portion 1b4 of the bottom surface 1b3, in other words, the angle formed between the side surface 1b1 and the electrode finger upper surface 3a, taking the side surface 1b1 as an example. Further, as described later, the duty of the IDT electrode 3 is set to 0.45 or less. The duty is a value represented by a ratio between the upper surface of the groove 1b, that is, the width of the electrode finger upper surface 3a and the value obtained by adding the distance between the electrode finger upper surface 3a and the adjacent electrode finger. Further, the Euler angles of the LiNbO 3 substrate 1 are (0 °, 80 ° to 130 °, 0 °). In the present embodiment, since the above configuration is provided, a large specific bandwidth Δf is obtained. This will be described more specifically below.
　図２は、ＬｉＮｂＯ３のオイラー角（０°，θ，０°）のθと、電気機械結合係数ｋ２との関係を示す図である。図２では、ＩＤＴ電極はＣｕにより形成されており、その厚みは０．１λ、０．１６λ、０．２λまたは０．５λとされている。ここで、λは伝搬する弾性波の波長である。 2, Euler angles of LiNbO 3 (0 °, θ, 0 °) is a diagram showing a theta of, the relationship between the electromechanical coupling factor k 2. In FIG. 2, the IDT electrode is made of Cu and has a thickness of 0.1λ, 0.16λ, 0.2λ, or 0.5λ. Here, λ is the wavelength of the propagating elastic wave.
　図２の実線Ｂは、Ｃｕの厚みが０．１λである場合の上記実施形態の弾性表面波装置１１におけるラブ波の電気機械結合係数ｋ２を示し、実線ＣはＣｕの厚みが０．１λである場合のレイリー波の電気機械結合係数ｋ２の変化を示す。また、破線Ｄは、Ｃｕの厚みが０．１λである場合のＬｉＮｂＯ３の上面に溝を形成せずに、上面上に厚み０．１λのＣｕ膜からなるＩＤＴ電極を形成した構造におけるラブ波の電気機械結合係数ｋ２の変化を示し、破線Ｅはレイリー波の電気機械結合係数ｋ２の変化を示す。 The solid line B in FIG. 2 shows the electromechanical coupling coefficient k 2 of the Love wave in the surface acoustic wave device 11 of the above embodiment when the thickness of Cu is 0.1 [lambda], the thickness of the solid line C is Cu 0.1 [lambda] It shows the change in electromechanical coupling coefficient k 2 of the Rayleigh wave in the case where. A broken line D indicates a Love wave in a structure in which an IDT electrode made of a Cu film having a thickness of 0.1λ is formed on the upper surface without forming a groove on the upper surface of LiNbO 3 when the thickness of Cu is 0.1λ. shows the change in electromechanical coupling coefficient k 2, the broken line E shows the change of the electromechanical coupling coefficient k 2 of the Rayleigh wave.
　また、図２中の二点鎖線Ｆ，実線Ｇ及び一点鎖線Ｈは、Ｃｕ厚みが、それぞれ、０．１６λ、０．２λまたは０．５λの場合の上記実施形態の弾性表面波装置１１におけるラブ波の電気機械結合係数ｋ２の変化を示す。 Also, the two-dot chain line F, the solid line G, and the one-dot chain line H in FIG. 2 indicate the rub in the surface acoustic wave device 11 of the above embodiment when the Cu thickness is 0.16λ, 0.2λ, or 0.5λ, respectively. It shows the change in electromechanical coupling coefficient k 2 of the waves.
　図２から明らかなように、オイラー角のθが８０°～１３０°の範囲内であれば、溝にＣｕを充填してなる弾性表面波装置１１では、ラブ波の電気機械結合係数ｋ２を０．３以上と大きくし得ることがわかる。従って、比帯域幅を効果的に高め得ることがわかる。 As can be seen from FIG. 2, in the surface acoustic wave device 11 in which the groove is filled with Cu if the Euler angle θ is in the range of 80 ° to 130 °, the electromechanical coupling coefficient k 2 of the Love wave is It can be seen that it can be increased to 0.3 or more. Therefore, it can be seen that the specific bandwidth can be effectively increased.
　なお、図２では、電極材料としてＣｕを用いた場合を示したが、電極材料としてＰｔ、ＡｕなどのＡｌよりも密度が大きい他の金属を用いた場合においても、オイラー角のθが８０°～１３０°の範囲内であれば、ラブ波の電気機械結合係数ｋ２を効果的に高め得ることが可能である。 2 shows the case where Cu is used as the electrode material, the Euler angle θ is 80 ° even when another metal having a higher density than Al such as Pt and Au is used as the electrode material. If it is within the range of ˜130 °, it is possible to effectively increase the electromechanical coupling coefficient k 2 of the Love wave.
　次に、電極材料を、Ｐｔ、Ｃｕとしたときの場合につき、それぞれ分けて説明することとする。 Next, the case where the electrode material is Pt and Cu will be described separately.
　（ＰｔからなるＩＤＴ電極の場合）
　電極材料としてＰｔを用いた。なお、電極材料はＰｔを主体として構成されておればよく、ここで、Ｐｔを主体とする、とは、Ｐｔの（密度×電極厚み）の値と、複数種の電極材料からなるＩＤＴ電極全体の密度と電極との厚みの積の合計との比が０．５を超える場合をいうものとする。ここで、ＩＤＴ電極全体の密度と電極厚みの積の合計とは、下記の式で表される値である。 (In the case of IDT electrode made of Pt)
Pt was used as the electrode material. The electrode material only needs to be mainly composed of Pt. Here, Pt is mainly composed of the value of Pt (density × electrode thickness) and the whole IDT electrode composed of a plurality of types of electrode materials. The ratio of the density of the electrode and the sum of the products of the thicknesses of the electrodes exceeds 0.5. Here, the sum of the product of the density of the entire IDT electrode and the electrode thickness is a value represented by the following equation.
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001
　上記式において、ρは密度、Ｔは電極厚みを示し、ｎはＩＤＴ電極を構成している電極層の数である。 In the above equation, ρ represents density, T represents electrode thickness, and n represents the number of electrode layers constituting the IDT electrode.
　ＬｉＮｂＯ３基板のオイラー角は（０°，１１２°，０°）とした。溝１ｂにおける傾斜角度Ａを種々変更し、ただし、ＰｔからなるＩＤＴ電極の厚みは０．１λとし、種々の弾性表面波装置１１を作製した。図３に、溝の傾斜角度Ａと、デューティと、ラブ波の比帯域幅Δｆとの関係を示す。なお、比帯域幅Δｆとは、弾性表面波装置１１における共振周波数をｆｒ、***振周波数をｆａとしたとき、（ｆａ－ｆｒ）／ｆｒで表される値である。 The Euler angles of the LiNbO 3 substrate were (0 °, 112 °, 0 °). Various surface acoustic wave devices 11 were manufactured by changing the inclination angle A in the groove 1b in various ways, except that the thickness of the IDT electrode made of Pt was 0.1λ. FIG. 3 shows the relationship between the groove inclination angle A, the duty, and the love wave specific bandwidth Δf. The specific bandwidth Δf is a value represented by (fa−fr) / fr where the resonance frequency in the surface acoustic wave device 11 is fr and the antiresonance frequency is fa.
　図３から明らかなように、傾斜角度Ａが５６°～８４°の範囲内であり、かつデューティが０．４５以下であれば、比帯域幅Δｆを０．２０以上とし得ることがわかる。 As is apparent from FIG. 3, if the inclination angle A is in the range of 56 ° to 84 ° and the duty is 0.45 or less, it can be seen that the specific bandwidth Δf can be 0.20 or more.
　また、図４は、上記弾性表面波装置１１におけるＰｔの膜厚すなわち溝の厚みを変化させた場合のＰｔの厚み（Ｈ／λ）と比帯域幅Δｆとの関係を示す。ここでは、上記溝の傾斜角度Ａは７８°とした。 FIG. 4 shows the relationship between the Pt thickness (H / λ) and the specific bandwidth Δf when the Pt film thickness, that is, the groove thickness in the surface acoustic wave device 11 is changed. Here, the inclination angle A of the groove was 78 °.
　図４から明らかなように、上記デューティが０．２～０．４５の範囲内であれば、ラブ波を励振し、大きな比帯域幅Δｆの得られることがわかる。なお、この場合、デューティが０．２未満では、ラブ波の励振状態が不安定であった。従って、ＰｔからなるＩＤＴ電極を用いた場合、デューティは０．２以上であることが望ましい。 As can be seen from FIG. 4, when the duty is in the range of 0.2 to 0.45, a Love wave is excited and a large specific bandwidth Δf is obtained. In this case, when the duty is less than 0.2, the Love wave excitation state is unstable. Therefore, when an IDT electrode made of Pt is used, the duty is desirably 0.2 or more.
　また、図４から明らかなように、デューティが０．２～０．４５の範囲内において、Ｐｔ膜の厚みＨ／λは、０．０６λ以上、０．５λ以下であることが望ましいことがわかる。それによって、比帯域幅Δｆを確実に０．２０以上、すなわち２０％以上とし得ることがわかる。よって、Ｐｔ膜の厚みは、０．０６λ以上、０．５λ以下であることが望ましい。また図４より、Ｐｔ膜の厚みは０．０８λ以上がより好ましい。 Further, as is apparent from FIG. 4, it is understood that the thickness H / λ of the Pt film is preferably 0.06λ or more and 0.5λ or less within the duty range of 0.2 to 0.45. . Accordingly, it can be seen that the specific bandwidth Δf can be surely set to 0.20 or more, that is, 20% or more. Therefore, the thickness of the Pt film is preferably 0.06λ or more and 0.5λ or less. From FIG. 4, the thickness of the Pt film is more preferably 0.08λ or more.
　（ＣｕからなるＩＤＴ電極の場合）
　電極材料としてＣｕを用いた。なお、電極材料はＣｕを主体として構成されておればよい。ＬｉＮｂＯ３基板のオイラー角は（０°，１１２°，０°）とした。溝１ｂにおける傾斜角度Ａを種々変更し、ただし、ＣｕからなるＩＤＴ電極の厚みは０．３５λとし、種々の弾性表面波装置１１を作製した。図５に、溝の傾斜角度Ａと、デューティと、比帯域幅Δｆとの関係を示す。なお、比帯域幅Δｆとは、弾性表面波装置１１における共振周波数をｆｒ、***振周波数をｆａとしたとき、（ｆａ－ｆｒ）／ｆｒで表される値である。 (In the case of IDT electrode made of Cu)
Cu was used as the electrode material. The electrode material only needs to be mainly composed of Cu. The Euler angles of the LiNbO 3 substrate were (0 °, 112 °, 0 °). Various surface acoustic wave devices 11 were prepared by changing the inclination angle A in the groove 1b in various ways, except that the thickness of the IDT electrode made of Cu was 0.35λ. FIG. 5 shows the relationship among the groove inclination angle A, the duty, and the specific bandwidth Δf. The specific bandwidth Δf is a value represented by (fa−fr) / fr where the resonance frequency in the surface acoustic wave device 11 is fr and the antiresonance frequency is fa.
　図５から明らかなように、傾斜角度Ａが５６°～８４°の範囲内であり、かつデューティが０．４５以下であれば、比帯域幅Δｆを０．２０以上とし得ることがわかる。 As is apparent from FIG. 5, if the inclination angle A is in the range of 56 ° to 84 ° and the duty is 0.45 or less, the specific bandwidth Δf can be 0.20 or more.
　また、図６は、上記弾性表面波装置１１におけるＣｕの膜厚すなわち溝の厚みを変化させた場合のＣｕの厚み（Ｈ／λ）と比帯域幅Δｆとの関係を示す。ここでは、上記溝の傾斜角度Ａは７８°とした。 FIG. 6 shows the relationship between the Cu thickness (H / λ) and the specific bandwidth Δf when the Cu film thickness, that is, the groove thickness in the surface acoustic wave device 11 is changed. Here, the inclination angle A of the groove was 78 °.
　図６から明らかなように、上記デューティが０．２５～０．４５の範囲内であれば、ラブ波を励振し、大きな比帯域幅Δｆの得られることがわかる。より好ましくは、デューティが０．４以下であればΔｆを２０％以上とし得ることが分かる。なお、この場合、デューティが０．２５未満では、ラブ波の励振状態が不安定であった。従って、ＣｕからなるＩＤＴ電極を用いた場合、デューティは０．２５以上であることが望ましい。 As can be seen from FIG. 6, when the duty is in the range of 0.25 to 0.45, a Love wave is excited and a large specific bandwidth Δf is obtained. More preferably, if the duty is 0.4 or less, it can be seen that Δf can be 20% or more. In this case, when the duty is less than 0.25, the Love wave excitation state is unstable. Therefore, when an IDT electrode made of Cu is used, the duty is desirably 0.25 or more.
　また、図６から明らかなように、デューティが０．２５～０．４５の範囲内において、Ｃｕ膜の厚みＨ／λは、０．１６λ以上、０．５λ以下であることが望ましいことがわかる。それによって、比帯域幅Δｆを確実に０．２０以上、すなわち２０％以上とし得ることがわかる。よって、Ｃｕ膜の厚みは、０．１６λ以上、０．５λ以下であることが望ましい。また、より好ましくは図６より０．１７λ以上が好ましい。また、デューティが０．２５～０．４の範囲内でかつＣｕ膜の厚みが０．１６λ～０．５λであれば、Δｆを２０％以上とし得ることが分かる。 Further, as apparent from FIG. 6, it is understood that the thickness H / λ of the Cu film is preferably 0.16λ or more and 0.5λ or less within the range of the duty of 0.25 to 0.45. . Accordingly, it can be seen that the specific bandwidth Δf can be surely set to 0.20 or more, that is, 20% or more. Therefore, the thickness of the Cu film is desirably 0.16λ or more and 0.5λ or less. Further, more preferably 0.17λ or more from FIG. It can also be seen that if the duty is in the range of 0.25 to 0.4 and the thickness of the Cu film is 0.16λ to 0.5λ, Δf can be 20% or more.
　（ＭｏからなるＩＤＴ電極の場合）
　電極材料としてＭｏを用いた。なお、電極材料はＭｏを主体として構成されておればよい。ＬｉＮｂＯ３基板のオイラー角は（０°，１１２°，０°）とした。溝１ｂにおける傾斜角度Ａを種々変更し、ただし、ＭｏからなるＩＤＴ電極の厚みは０．２λとし、種々の弾性表面波装置１１を作製した。図７に、溝の傾斜角度Ａと、デューティと、比帯域幅Δｆとの関係を示す。なお、比帯域幅Δｆとは、弾性表面波装置１１における共振周波数をｆｒ、***振周波数をｆａとしたとき、（ｆａ－ｆｒ）／ｆｒで表される値である。 (In case of IDT electrode made of Mo)
Mo was used as the electrode material. The electrode material only needs to be mainly composed of Mo. The Euler angles of the LiNbO 3 substrate were (0 °, 112 °, 0 °). Various surface acoustic wave devices 11 were manufactured by changing the inclination angle A in the groove 1b in various ways, except that the thickness of the IDT electrode made of Mo was 0.2λ. FIG. 7 shows the relationship between the groove inclination angle A, the duty, and the specific bandwidth Δf. The specific bandwidth Δf is a value represented by (fa−fr) / fr where the resonance frequency in the surface acoustic wave device 11 is fr and the antiresonance frequency is fa.
　図７から明らかなように、傾斜角度Ａが５６°～８４°の範囲内であり、かつデューティが０．４５以下であれば、比帯域幅Δｆを０．２０以上とし得ることがわかる。 7 that the specific bandwidth Δf can be 0.20 or more when the inclination angle A is in the range of 56 ° to 84 ° and the duty is 0.45 or less.
　また、図８は、上記弾性表面波装置１１におけるＭｏの膜厚すなわち溝の厚みを変化させた場合のＭｏの厚み（Ｈ／λ）と比帯域幅Δｆとの関係を示す。ここでは、上記溝の傾斜角度Ａは７８°とした。 FIG. 8 shows the relationship between the Mo thickness (H / λ) and the specific bandwidth Δf when the Mo film thickness, that is, the groove thickness in the surface acoustic wave device 11 is changed. Here, the inclination angle A of the groove was 78 °.
　図８から明らかなように、上記デューティが０．３５～０．４５の範囲内であれば、ラブ波を励振し、大きな比帯域幅Δｆの得られることがわかる。 As can be seen from FIG. 8, when the duty is in the range of 0.35 to 0.45, a Love wave is excited and a large specific bandwidth Δf can be obtained.
　また、図８から明らかなように、デューティが０．３５～０．４５の範囲内において、Ｍｏ膜の厚みＨ／λは、０．１６λ以上、０．３λ以下であることが望ましいことがわかる。それによって、比帯域幅Δｆを確実に０．２３以上、すなわち２３％以上とし得ることがわかる。よって、Ｍｏ膜の厚みは、０．１６λ以上、０．３λ以下であることが望ましい。 Further, as is apparent from FIG. 8, it is understood that the thickness H / λ of the Mo film is preferably 0.16λ or more and 0.3λ or less within a duty range of 0.35 to 0.45. . Accordingly, it can be seen that the specific bandwidth Δf can be reliably set to 0.23 or more, that is, 23% or more. Therefore, the thickness of the Mo film is desirably 0.16λ or more and 0.3λ or less.
　（ＮｉからなるＩＤＴ電極の場合）
　電極材料としてＮｉを用いた。なお、電極材料はＮｉを主体として構成されておればよい。ＬｉＮｂＯ３基板のオイラー角は（０°，１１２°，０°）とした。溝１ｂにおける傾斜角度Ａを種々変更し、ただし、ＮｉからなるＩＤＴ電極の厚みは０．２５λとし、種々の弾性表面波装置１１を作製した。図９に、溝の傾斜角度Ａと、デューティと、比帯域幅Δｆとの関係を示す。なお、比帯域幅Δｆとは、弾性表面波装置１１における共振周波数をｆｒ、***振周波数をｆａとしたとき、（ｆａ－ｆｒ）／ｆｒで表される値である。 (In the case of IDT electrode made of Ni)
Ni was used as the electrode material. In addition, the electrode material should just be comprised mainly by Ni. The Euler angles of the LiNbO 3 substrate were (0 °, 112 °, 0 °). Various surface acoustic wave devices 11 were manufactured by changing the inclination angle A in the groove 1b in various ways, except that the thickness of the IDT electrode made of Ni was 0.25λ. FIG. 9 shows the relationship among the groove inclination angle A, the duty, and the specific bandwidth Δf. The specific bandwidth Δf is a value represented by (fa−fr) / fr where the resonance frequency in the surface acoustic wave device 11 is fr and the antiresonance frequency is fa.
　図９から明らかなように、傾斜角度Ａが５６°～８４°の範囲内であり、かつデューティが０．４５以下であれば、比帯域幅Δｆを０．２２以上とし得ることがわかる。 As is apparent from FIG. 9, when the inclination angle A is in the range of 56 ° to 84 ° and the duty is 0.45 or less, the specific bandwidth Δf can be 0.22 or more.
　また、図１０は、上記弾性表面波装置１１におけるＮｉの膜厚すなわち溝の厚みを変化させた場合のＮｉの厚み（Ｈ／λ）と比帯域幅Δｆとの関係を示す。ここでは、上記溝の傾斜角度Ａは７８°とした。 FIG. 10 shows the relationship between the Ni thickness (H / λ) and the specific bandwidth Δf when the Ni film thickness, that is, the groove thickness in the surface acoustic wave device 11 is changed. Here, the inclination angle A of the groove was 78 °.
　図１０から明らかなように、上記デューティが０．４～０．４５の範囲内であれば、ラブ波を励振し、大きな比帯域幅Δｆの得られることがわかる。 As can be seen from FIG. 10, when the duty is in the range of 0.4 to 0.45, a Love wave is excited and a large specific bandwidth Δf is obtained.
　また、図１０から明らかなように、デューティが０．４～０．４５の範囲内において、Ｎｉ膜の厚みＨ／λは、０．２λ以上、０．３λ以下であることが望ましいことがわかる。それによって、比帯域幅Δｆを確実に０．２２以上、すなわち２２％以上とし得ることがわかる。よって、Ｎｉ膜の厚みは、０．２λ以上、０．３λ以下であることが望ましい。 Further, as is apparent from FIG. 10, it is understood that the thickness H / λ of the Ni film is preferably 0.2λ or more and 0.3λ or less within the duty range of 0.4 to 0.45. . Accordingly, it can be seen that the specific bandwidth Δf can be surely set to 0.22 or more, that is, 22% or more. Therefore, the thickness of the Ni film is preferably 0.2λ or more and 0.3λ or less.
　（ＴａからなるＩＤＴ電極の場合）
　電極材料としてＴａを用いた。なお、電極材料はＴａを主体として構成されておればよい。ＬｉＮｂＯ３基板のオイラー角は（０°，１１２°，０°）とした。溝１ｂにおける傾斜角度Ａを種々変更し、ただし、ＴａからなるＩＤＴ電極の厚みは０．１５λとし、種々の弾性表面波装置１１を作製した。図１１に、溝の傾斜角度Ａと、デューティと、比帯域幅Δｆとの関係を示す。なお、比帯域幅Δｆとは、弾性表面波装置１１における共振周波数をｆｒ、***振周波数をｆａとしたとき、（ｆａ－ｆｒ）／ｆｒで表される値である。 (In the case of IDT electrode made of Ta)
Ta was used as the electrode material. Note that the electrode material may be composed mainly of Ta. The Euler angles of the LiNbO 3 substrate were (0 °, 112 °, 0 °). Various surface acoustic wave devices 11 were manufactured by changing the inclination angle A in the groove 1b in various ways, except that the thickness of the IDT electrode made of Ta was 0.15λ. FIG. 11 shows the relationship between the groove inclination angle A, the duty, and the specific bandwidth Δf. The specific bandwidth Δf is a value represented by (fa−fr) / fr where the resonance frequency in the surface acoustic wave device 11 is fr and the antiresonance frequency is fa.
　図１１から明らかなように、傾斜角度Ａが５６°～８４°の範囲内であり、かつデューティが０．４５以下であれば、比帯域幅Δｆを０．２３以上とし得ることがわかる。 As can be seen from FIG. 11, if the inclination angle A is in the range of 56 ° to 84 ° and the duty is 0.45 or less, the specific bandwidth Δf can be 0.23 or more.
　また、図１２は、上記弾性表面波装置１１におけるＴａの膜厚すなわち溝の厚みを変化させた場合のＴａの厚み（Ｈ／λ）と比帯域幅Δｆとの関係を示す。ここでは、上記溝の傾斜角度Ａは７８°とした。 FIG. 12 shows the relationship between the Ta thickness (H / λ) and the specific bandwidth Δf when the Ta film thickness, that is, the groove thickness in the surface acoustic wave device 11 is changed. Here, the inclination angle A of the groove was 78 °.
　図１２から明らかなように、上記デューティが０．３～０．４５の範囲内であれば、ラブ波を励振し、大きな比帯域幅Δｆの得られることがわかる。より好ましくは、デューティが０．４以下であればΔｆを２３．５％以上とし得ることが分かる。なお、この場合、デューティが０．３未満では、ラブ波の励振状態が不安定であった。従って、ＴａからなるＩＤＴ電極を用いた場合、デューティは０．３以上であることが望ましい。 As can be seen from FIG. 12, when the duty is in the range of 0.3 to 0.45, a Love wave is excited and a large specific bandwidth Δf is obtained. More preferably, it can be seen that Δf can be 23.5% or more when the duty is 0.4 or less. In this case, when the duty is less than 0.3, the excitation state of the Love wave is unstable. Therefore, when an IDT electrode made of Ta is used, the duty is desirably 0.3 or more.
　また、図１２から明らかなように、デューティが０．３～０．４５の範囲内において、Ｔａ膜の厚みＨ／λは、０．１１λ以上、０．３λ以下であることが望ましいことがわかる。それによって、比帯域幅Δｆを確実に０．２１以上、すなわち２１％以上とし得ることがわかる。よって、Ｔａ膜の厚みは、０．１１λ以上、０．３λ以下であることが望ましい。 Further, as is apparent from FIG. 12, it can be understood that the thickness H / λ of the Ta film is preferably 0.11λ or more and 0.3λ or less in the range of duty of 0.3 to 0.45. . Accordingly, it can be seen that the specific bandwidth Δf can be reliably set to 0.21 or more, that is, 21% or more. Therefore, the thickness of the Ta film is preferably 0.11λ or more and 0.3λ or less.
　（ＷからなるＩＤＴ電極の場合）
　電極材料としてＷを用いた。なお、電極材料はＷを主体として構成されておればよい。ＬｉＮｂＯ３基板のオイラー角は（０°，１１２°，０°）とした。溝１ｂにおける傾斜角度Ａを種々変更し、ただし、ＷからなるＩＤＴ電極の厚みは０．１λとし、種々の弾性表面波装置１１を作製した。図１３に、溝の傾斜角度Ａと、デューティと、比帯域幅Δｆとの関係を示す。なお、比帯域幅Δｆとは、弾性表面波装置１１における共振周波数をｆｒ、***振周波数をｆａとしたとき、（ｆａ－ｆｒ）／ｆｒで表される値である。 (In case of IDT electrode made of W)
W was used as the electrode material. In addition, the electrode material should just be comprised by making W into a main body. The Euler angles of the LiNbO 3 substrate were (0 °, 112 °, 0 °). Various surface acoustic wave devices 11 were manufactured by changing the inclination angle A in the groove 1b in various ways, except that the thickness of the IDT electrode made of W was 0.1λ. FIG. 13 shows the relationship among the groove inclination angle A, the duty, and the specific bandwidth Δf. The specific bandwidth Δf is a value represented by (fa−fr) / fr where the resonance frequency in the surface acoustic wave device 11 is fr and the antiresonance frequency is fa.
　図１３から明らかなように、傾斜角度Ａが５６°～８４°の範囲内であり、かつデューティが０．４５以下であれば、比帯域幅Δｆを０．２３以上とし得ることがわかる。 As can be seen from FIG. 13, if the inclination angle A is in the range of 56 ° to 84 ° and the duty is 0.45 or less, the specific bandwidth Δf can be 0.23 or more.
　また、図１４は、上記弾性表面波装置１１におけるＷの膜厚すなわち溝の厚みを変化させた場合のＷの厚み（Ｈ／λ）と比帯域幅Δｆとの関係を示す。ここでは、上記溝の傾斜角度Ａは７８°とした。 FIG. 14 shows the relationship between the W thickness (H / λ) and the specific bandwidth Δf when the thickness of the W in the surface acoustic wave device 11, that is, the thickness of the groove is changed. Here, the inclination angle A of the groove was 78 °.
　図１４から明らかなように、上記デューティが０．３～０．４５の範囲内であれば、ラブ波を励振し、大きな比帯域幅Δｆの得られることがわかる。 As can be seen from FIG. 14, when the duty is in the range of 0.3 to 0.45, a Love wave is excited and a large specific bandwidth Δf is obtained.
　また、図１４から明らかなように、デューティが０．３～０．４５の範囲内において、Ｗ膜の厚みＨ／λは、０．０８λ以上、０．３λ以下であることが望ましいことがわかる。それによって、比帯域幅Δｆを確実に０．２３以上、すなわち２３％以上とし得ることがわかる。よって、Ｗ膜の厚みは、０．０８λ以上、０．３λ以下であることが望ましい。 Further, as is apparent from FIG. 14, it is understood that the thickness H / λ of the W film is preferably 0.08λ or more and 0.3λ or less within a duty range of 0.3 to 0.45. . Accordingly, it can be seen that the specific bandwidth Δf can be reliably set to 0.23 or more, that is, 23% or more. Therefore, the thickness of the W film is desirably 0.08λ or more and 0.3λ or less.
　（ＩＤＴ電極を構成する金属材料）
　図３～図１４では、ＩＤＴ電極がＰｔ、Ｃｕ、Ｍｏ、Ｎｉ、ＴａまたはＷを主体として構成される場合につき説明したが、本発明では、ＩＤＴ電極は、Ａｌよりも密度が大きい金属により構成されておればよく、上記各金属に限定されるものではない。 (Metal material constituting IDT electrode)
3 to 14, the IDT electrode is mainly composed of Pt, Cu, Mo, Ni, Ta or W. However, in the present invention, the IDT electrode is composed of a metal having a density higher than that of Al. What is necessary is just to be carried out and it is not limited to said each metal.
　また、図１（ａ）及び（ｂ）では、一ポート型弾性表面波共振子につき説明したが、共振子型弾性表面波フィルタなどの他の弾性表面波装置にも本発明を適用することができる。従って、ＩＤＴ電極の数や配置についても、弾性表面波装置の機能に応じて適宜変形することができる。 1A and 1B, the one-port surface acoustic wave resonator has been described. However, the present invention can also be applied to other surface acoustic wave devices such as a resonator type surface acoustic wave filter. it can. Accordingly, the number and arrangement of the IDT electrodes can be appropriately modified according to the function of the surface acoustic wave device.
１…ＬｉＮｂＯ３基板
１ａ…上面
１ｂ…溝
１ｂ１，１ｂ２…側面
１ｂ３…底面
１ｂ４…延長部
３…ＩＤＴ電極
３ａ…電極指上面
１１…弾性表面波装置
１２，１３…反射器 1 ... LiNbO 3 substrate 1a ... top 1b ... grooves 1b1 and 1b2 ... side 1b3 ... bottom 1b4 ... extension 3 ... IDT electrode 3a ... electrode finger top 11 ... surface acoustic wave devices 12 and 13 ... reflector

Claims (13)

  1. 　上面に溝が形成されており、かつオイラー角が（０°，８０°～１３０°，０°）の範囲にあるＬｉＮｂＯ３基板と、
    　前記ＬｉＮｂＯ３基板の上面に設けられている前記溝に充填されており、かつアルミニウムよりも密度が大きい金属からなるＩＤＴ電極とを備え、ラブ波を利用しており、
    　前記溝が前記ＩＤＴ電極の電極指の延びる方向に延びており、該溝の横断面における溝の側面が傾斜しており、該側面の前記溝の底部の延長面とのなす角度である傾斜角度Ａが５６°～８４°の範囲内にあり、前記ＩＤＴ電極のデューティが０．４５以下である、弾性表面波装置。     A LiNbO 3 substrate having a groove formed on the upper surface and having an Euler angle in the range of (0 °, 80 ° to 130 °, 0 °);
    An IDT electrode that is filled in the groove provided on the upper surface of the LiNbO 3 substrate and made of a metal having a density higher than that of aluminum, and uses a Love wave;
    The groove extends in the direction in which the electrode finger of the IDT electrode extends, the side surface of the groove in the cross section of the groove is inclined, and an inclination angle that is an angle between the side surface and the extended surface of the bottom of the groove A surface acoustic wave device in which A is in the range of 56 ° to 84 °, and the duty of the IDT electrode is 0.45 or less.
  2. 　前記ＩＤＴ電極がＰｔを主体とする材料からなり、前記デューティが０．２以上である、請求項１に記載の弾性表面波装置。 The surface acoustic wave device according to claim 1, wherein the IDT electrode is made of a material mainly containing Pt, and the duty is 0.2 or more.
  3. 　前記ＩＤＴ電極の電極指の周期により定まる波長をλとしたときに、前記ＩＤＴ電極の厚みが０．０６λ以上、０．５λ以下の範囲にある、請求項２に記載の弾性表面波装置。 The surface acoustic wave device according to claim 2, wherein the thickness of the IDT electrode is in the range of 0.06λ or more and 0.5λ or less, where λ is a wavelength determined by the period of the electrode fingers of the IDT electrode.
  4. 　前記ＩＤＴ電極がＣｕを主体とする材料からなり、前記デューティが０．２５以上である、請求項１に記載の弾性表面波装置。 The surface acoustic wave device according to claim 1, wherein the IDT electrode is made of a material mainly containing Cu, and the duty is 0.25 or more.
  5. 　前記ＩＤＴ電極の電極指の周期により定まる波長をλとしたときに、前記ＩＤＴ電極の厚みが０．１６λ以上、０．５λ以下の範囲にある、請求項４に記載の弾性表面波装置。 The surface acoustic wave device according to claim 4, wherein the thickness of the IDT electrode is in the range of 0.16λ to 0.5λ, where λ is a wavelength determined by the period of the electrode fingers of the IDT electrode.
  6. 　前記ＩＤＴ電極がＭｏを主体とする材料からなり、前記デューティが０．３５以上である、請求項１に記載の弾性表面波装置。 The surface acoustic wave device according to claim 1, wherein the IDT electrode is made of a material mainly composed of Mo, and the duty is 0.35 or more.
  7. 　前記ＩＤＴ電極の電極指の周期により定まる波長をλとしたときに、前記ＩＤＴ電極の厚みが０．１６λ以上、０．３λ以下にある、請求項６に記載の弾性表面波装置。 The surface acoustic wave device according to claim 6, wherein the thickness of the IDT electrode is 0.16λ or more and 0.3λ or less, where λ is a wavelength determined by a period of electrode fingers of the IDT electrode.
  8. 　前記ＩＤＴ電極がＮｉを主体とする材料からなり、前記デューティが０．４以上である、請求項１に記載の弾性表面波装置。 The surface acoustic wave device according to claim 1, wherein the IDT electrode is made of a material mainly composed of Ni, and the duty is 0.4 or more.
  9. 　前記ＩＤＴ電極の電極指の周期により定まる波長をλとしたときに、前記ＩＤＴ電極の厚みが０．２λ以上、０．３λ以下にある、請求項８に記載の弾性表面波装置。 The surface acoustic wave device according to claim 8, wherein the thickness of the IDT electrode is 0.2λ or more and 0.3λ or less, where λ is a wavelength determined by a period of electrode fingers of the IDT electrode.
  10. 　前記ＩＤＴ電極がＴａを主体とする材料からなり、前記デューティが０．３以上である、請求項１に記載の弾性表面波装置。 The surface acoustic wave device according to claim 1, wherein the IDT electrode is made of a material mainly composed of Ta, and the duty is 0.3 or more.
  11. 　前記ＩＤＴ電極の電極指の周期により定まる波長をλとしたときに、前記ＩＤＴ電極の厚みが０．１１λ以上、０．３λ以下にある、請求項１０に記載の弾性表面波装置。 The surface acoustic wave device according to claim 10, wherein the thickness of the IDT electrode is 0.11λ or more and 0.3λ or less, where λ is a wavelength determined by a period of electrode fingers of the IDT electrode.
  12. 　前記ＩＤＴ電極がＷを主体とする材料からなり、前記デューティが０．３以上である、請求項１に記載の弾性表面波装置。 The surface acoustic wave device according to claim 1, wherein the IDT electrode is made of a material mainly composed of W, and the duty is 0.3 or more.
  13. 　前記ＩＤＴ電極の電極指の周期により定まる波長をλとしたときに、前記ＩＤＴ電極の厚みが０．０８λ以上、０．３λ以下にある、請求項１２に記載の弾性表面波装置。 The surface acoustic wave device according to claim 12, wherein the thickness of the IDT electrode is 0.08λ or more and 0.3λ or less, where λ is a wavelength determined by a period of electrode fingers of the IDT electrode.
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