JP2006148279A - Surface acoustic wave device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a means for substantially equalizing the frequency temperature characteristics of an SH type surface acoustic device to those of a surface acoustic device employing a Rayleigh wave. <P>SOLUTION: At least one IDT electrode of an alloy principally comprising aluminum is arranged on a crystal substrate of Euler angle (0°, 110°-150°, 90°±2°) and an SiO<SB>2</SB>film is stuck to cover the IDT electrode thus obtaining an SH type surface acoustic device. The SH type surface acoustic device is constituted by setting the standardized thickness of the SiO<SB>2</SB>film in the range of 1.7%-3.0%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、ＳＨ型弾性表面波を用いた弾性表面波デバイスに関し、特にＳＴカット水晶基板上をＺ’軸方向に伝搬するＳＨ型弾性表面波を用いて構成した弾性表面波デバイスにおいて、電極パターン上に付着したＳｉＯ_２膜を適切に設定することにより、周波数温度特性を改善した弾性表面波デバイスに関するものである。 The present invention relates to a surface acoustic wave device using an SH type surface acoustic wave, and more particularly, to an electrode pattern in a surface acoustic wave device configured using an SH type surface acoustic wave propagating on an ST cut quartz substrate in the Z′-axis direction. The present invention relates to a surface acoustic wave device in which frequency temperature characteristics are improved by appropriately setting a SiO ₂ film adhered thereon.

近年、弾性表面波デバイスは通信分野で広く利用され、高性能、小型、量産性等の優れた特徴を有することから特に携帯電話機等に多く用いられている。
ＳＴカット水晶基板上をＸ軸方向に伝搬する弾性表面波（レイリー波）を用いて構成した狭帯域の共振器型フィルタが以前から使用されていた。図３は１次モードと２次モードとを用いた横結合型二重モードＳＡＷフィルタの構成を示す平面図であって、ＳＴカット水晶基板１１の主表面上に２つのＩＤＴ電極１２、１３をこれらが励起する弾性表面波の伝搬方向と直交する方向に近接配置すると共に、併置したＩＤＴ電極１２、１３の両側にグレーティング反射器（以下、反射器と称す）１４ａ、１４ｂを配設して、横結合二重モードＳＡＷフィルタを構成する。 In recent years, surface acoustic wave devices have been widely used in the communication field, and are often used particularly for cellular phones because they have excellent characteristics such as high performance, small size, and mass productivity.
A narrow-band resonator type filter constructed using a surface acoustic wave (Rayleigh wave) propagating in the X-axis direction on an ST-cut quartz substrate has been used for some time. FIG. 3 is a plan view showing a configuration of a laterally coupled dual mode SAW filter using a primary mode and a secondary mode, and two IDT electrodes 12 and 13 are formed on the main surface of an ST-cut quartz substrate 11. The grating reflectors (hereinafter referred to as reflectors) 14a and 14b are disposed on both sides of the IDT electrodes 12 and 13 disposed side by side in the direction orthogonal to the propagation direction of the surface acoustic wave excited by these, A laterally coupled double mode SAW filter is constructed.

ＩＤＴ電極１２、１３はそれぞれ互いに間挿し合う複数本の電極指を有する一対の櫛形電極により形成され、ＩＤＴ電極１２の一方の櫛形電極は入力端子ＩＮ１に接続すると共に、他方の櫛形電極は入力端子ＩＮ２に接続する。さらに、ＩＤＴ電極１３の一方の櫛形電極は出力端子ＯＵＴ１に接続すると共に、他方の櫛形電極はＯＵＴ２に接続して横結合二重モードＳＡＷフィルタを構成する。   The IDT electrodes 12 and 13 are each formed by a pair of comb electrodes having a plurality of electrode fingers interleaved with each other, and one comb electrode of the IDT electrode 12 is connected to the input terminal IN1, and the other comb electrode is an input terminal. Connect to IN2. Further, one comb electrode of the IDT electrode 13 is connected to the output terminal OUT1, and the other comb electrode is connected to OUT2 to constitute a laterally coupled double mode SAW filter.

ＩＤＴ電極１２、１３で励起された弾性表面波は反射器１４ａ、１４ｂの間で音響結合が生じ、その内ＩＤＴ電極パターンにより表面波の伝搬方向と直交する方向に、振動変位分布が対称な１次モード（共振周波数ｆ１）と、反対称な２次モード（共振周波数ｆ２）とが強勢に励振され、適当な終端を施すことにより横結合型二重モードＳＡＷフィルタとして動作し、その帯域幅は（f2−f1）に比例することがよく知られている。   The surface acoustic waves excited by the IDT electrodes 12 and 13 are acoustically coupled between the reflectors 14a and 14b, and the vibration displacement distribution is symmetric 1 in the direction perpendicular to the propagation direction of the surface waves due to the IDT electrode pattern. The secondary mode (resonance frequency f1) and the antisymmetric secondary mode (resonance frequency f2) are vigorously excited, and operate as a laterally coupled double-mode SAW filter by applying appropriate terminations. It is well known that it is proportional to (f2-f1).

しかし、ＳＴカット水晶基板に励起されるレイリー波を用いたＳＡＷデバイスの電気機械結合係数は小さく、例えばＳＡＷフィルタを構成すると帯域幅が制限されるという問題と、反射係数が小さいため反射器の本数を多く必要とするという問題があった。これを解決するためにＳＴカット水晶基板上をＺ’軸方向に伝搬するＳＨ波を用いた弾性表面波デバイス（ＳＨ型弾性表面波デバイス）が発明された。ＳＨ型弾性表面波の伝搬速度は、レイリー波のそれよりも約１．６倍と速く、高周波化に適している。特開２００２−３３００５１号公報には、オイラー角(０°,１１０°〜１５０°，９０°±２°)、ＳＴカット９０°Ｘ軸伝搬の水晶基板（回転角では２０〜６０°回転Ｙ板）に電極材料としてアルミニウムを用いた場合、電極の膜厚の変化に対する伝搬速度の変化の割合が小さいこと、電気機械結合係数がレイリー波のそれに比べて１．５倍以上大きいこと、反射器１本当たりの反射係数が３０％を超えるようになり、数本の反射器で十分な反射率を確保できると記されている。   However, the electromechanical coupling coefficient of a SAW device using Rayleigh waves excited on an ST-cut quartz substrate is small. For example, the configuration of a SAW filter limits the bandwidth and the number of reflectors because the reflection coefficient is small. There was a problem of needing a lot. In order to solve this, a surface acoustic wave device (SH type surface acoustic wave device) using an SH wave propagating on an ST cut quartz substrate in the Z′-axis direction has been invented. The propagation speed of the SH type surface acoustic wave is about 1.6 times faster than that of the Rayleigh wave, and is suitable for higher frequency. Japanese Patent Laid-Open No. 2002-330051 discloses an Euler angle (0 °, 110 ° to 150 °, 90 ° ± 2 °), ST cut 90 ° X-axis propagation quartz substrate (rotation angle 20 to 60 ° rotated Y plate) When aluminum is used as the electrode material, the ratio of the change in the propagation speed to the change in the electrode film thickness is small, the electromechanical coupling coefficient is 1.5 times or more larger than that of the Rayleigh wave, the reflector 1 It is stated that the reflection coefficient per book exceeds 30%, and a sufficient reflectance can be secured with several reflectors.

図４は上記公報に開示されている縦結合共振子フィルタの構成を示す図で、オイラー角(０°,１１０°〜１５０°，９０°±２°)、ＳＴカット９０°Ｘ軸伝搬の水晶基板（回転角では２０〜６０°回転Ｙ板）２１上にＳＨ波を励振する２つのＩＤＴ電極２２、２３を近接して配置し、これらの両側にＳＨ波を反射する２つの反射器２４ａ、２４ｂを配設して縦結合共振子フィルタ（縦結合二重モードＳＡＷフィルタ）を構成している。電極パターンにはアルミニウムを主とした電極材料を用い、その規格化膜厚Ｈ／λ（Ｈは電極膜厚、λはＳＨ型弾性表面波の波長）は０．０２５から０．１３５となるように構成すると記されている。   FIG. 4 is a diagram showing the configuration of the longitudinally coupled resonator filter disclosed in the above publication. A crystal with Euler angles (0 °, 110 ° to 150 °, 90 ° ± 2 °) and ST cut 90 ° X-axis propagation. Two IDT electrodes 22 and 23 for exciting SH waves are arranged close to each other on a substrate (rotation angle 20 to 60 ° rotation Y plate) 21, and two reflectors 24a for reflecting the SH waves on both sides thereof. 24b is provided to constitute a longitudinally coupled resonator filter (longitudinal coupled double mode SAW filter). For the electrode pattern, an electrode material mainly made of aluminum is used, and its normalized film thickness H / λ (H is the electrode film thickness, λ is the wavelength of the SH type surface acoustic wave) is 0.025 to 0.135. It is written that it is composed.

図４に示した電極パターンを用い、オイラー角(０°,１２６°，９０°)のＳＴカット水晶基板上にＩＤＴ電極２２、２３の対数をそれぞれ７０対、反射器２４ａ、２４ｂの本数をそれぞれ３６０本、ライン占有率（ライン幅ＬとスペースＳとの和に対するライン幅の比）を５０％、交差幅を１００λ、電極材料はアルミニウムを主成分とし、その規格化膜厚（Ｈ／λ）を２．２％に設定したＳＨ型縦結合二重モードＳＡＷフィルタを構成し、そのＳＡＷフィルタの周波数温度特性を測定した。その結果、ＳＡＷフィルタの周波数温度特性は負の２次曲線を呈し、２次温度係数βは約−５×１０^−８／℃^２であった。
特開２００２−３３００５１号公報 特開２００４−４０６３６号公報 特開平７−２１２１７４ 号公報 Using the electrode pattern shown in FIG. 4, 70 pairs of IDT electrodes 22 and 23 and 70 pairs of reflectors 24a and 24b are respectively formed on an ST cut quartz substrate with Euler angles (0 °, 126 ° and 90 °). 360 lines, line occupation ratio (ratio of line width to sum of line width L and space S) is 50%, intersection width is 100λ, electrode material is mainly composed of aluminum, and its normalized film thickness (H / λ) An SH type longitudinally coupled double mode SAW filter with a value of 2.2% was constructed, and the frequency temperature characteristics of the SAW filter were measured. As a result, the frequency temperature characteristic of the SAW filter exhibited a negative quadratic curve, and the secondary temperature coefficient β was about −5 × 10 ⁻⁸ / ° C. ² .
JP 2002-330051 A JP 2004-40636 A JP-A-7-212174

しかしながら、オイラー角(０°,１２６°，９０°)のＳＴカット水晶基板上に形成されるＳＨ型縦結合二重モードＳＡＷフィルタは高周波に適しており、電気機械結合係数も大きく、広い帯域幅が得られるという特徴は有するものの、レイリー波を用いたＳＡＷフィルタの周波数温度特性の２次温度係数が約−３×１０^−８／℃^２であるのに比し、ＳＨ型縦結合二重モードＳＡＷフィルタのそれは約−５×１０^−８／℃^２と大きく、レイリー波を用いたフィルタに比べ劣るという問題があった。
特開２００４−４０６３６号公報には、３６°回転Ｙ板ＬｉＴａＯ_３基板上にＩＤＴ電極及び反射器を配して弾性表面波フィルタを構成し、ＩＤＴ電極及び反射器を保護するため、あるいは弾性表面波フィルタの周波数温度特性を改善するため、電極パターンの全面にＳｉＯ_２膜を付着した例が開示されており、ＳｉＯ_２膜の規格化膜厚Ｈｓが０．１５から０．４の範囲であれば、温度特性ＴＣＦを±１５ｐｐｍ以内とし得ると記されている。そして、規格化膜厚Ｈｓを０．１５より薄くすると温度特性ＴＣＦが大幅に劣化することが記述されている。
また、特開平７−２１２１７４号公報には、圧電基板（回転ＹカットＸ伝搬タンタル酸リチウム）上に十分に厚い非金属膜を形成することにより、圧電基板と非金属膜との境界近傍に発生する弾性境界波を用いたデバイスが開示されている。これによると非金属膜としてＳｉＯ_２膜を用いた場合、その規格化膜厚ｈ／λは１以上とすることにより良好な温度特性が達成できると記している。
しかし、特開２００４−４０６３６号公報に記された、ＬｉＴａＯ_３基板上に形成された弾性表面波フィルタの周波数温度特性は１次特性であり、本願出願者が改善を図るＳＨ型縦結合二重モードＳＡＷフィルタの温度特性は負の２次特性であり、本質的の異なるという問題があった。また、特開平７−２１２１７４号公報の弾性境界波は圧電基板上に規格化膜厚ｈ／λの値が１を越す厚い非金属膜を付着して構成するため、ＳＨ型縦結合二重モードＳＡＷフィルタの挿入損失を低下させるおそれがあり、利用できないという問題があった。 However, the SH type longitudinally coupled double mode SAW filter formed on an Euler angle (0 °, 126 °, 90 °) ST-cut quartz substrate is suitable for high frequencies, has a large electromechanical coupling coefficient, and has a wide bandwidth. Although the second-order temperature coefficient of the frequency temperature characteristic of the SAW filter using Rayleigh waves is about −3 × 10 ⁻⁸ / ° C. ² , the SH type longitudinally coupled double mode The SAW filter has a large size of about −5 × 10 ⁻⁸ / ° C. ² , which is inferior to a filter using Rayleigh waves.
Japanese Patent Laid-Open No. 2004-40636 discloses that a surface acoustic wave filter is formed by arranging an IDT electrode and a reflector on a 36 ° rotated Y-plate LiTaO ₃ substrate to protect the IDT electrode and the reflector, or an elastic surface. In order to improve the frequency temperature characteristics of the wave filter, an example in which an SiO ₂ film is attached to the entire surface of the electrode pattern is disclosed, and the normalized film thickness Hs of the SiO ₂ film is in the range of 0.15 to 0.4. For example, it is described that the temperature characteristic TCF can be within ± 15 ppm. Further, it is described that when the normalized film thickness Hs is made smaller than 0.15, the temperature characteristic TCF is greatly deteriorated.
Japanese Patent Laid-Open No. 7-212174 discloses that a sufficiently thick non-metallic film is formed on a piezoelectric substrate (rotated Y-cut X-propagating lithium tantalate), thereby generating near the boundary between the piezoelectric substrate and the non-metallic film. A device using boundary acoustic waves is disclosed. According to this, when a SiO ₂ film is used as the non-metal film, it is stated that good temperature characteristics can be achieved by setting the normalized film thickness h / λ to 1 or more.
However, the frequency temperature characteristic of the surface acoustic wave filter formed on the LiTaO ₃ substrate described in Japanese Patent Application Laid-Open No. 2004-40636 is a first-order characteristic, and the SH type longitudinally coupled double that the applicant of the present application intends to improve is shown. The temperature characteristic of the mode SAW filter is a negative secondary characteristic and has a problem that it is essentially different. In addition, the boundary acoustic wave disclosed in Japanese Patent Laid-Open No. 7-212174 is formed by adhering a thick non-metallic film having a normalized film thickness h / λ exceeding 1 on a piezoelectric substrate. There is a possibility that the insertion loss of the SAW filter may be reduced, and there is a problem that the SAW filter cannot be used.

本発明に係る弾性表面波デバイスの請求項１の発明は、オイラー角（０°，１１０°〜１５０°，９０°±２°）の水晶基板上に少なくともの１つのアルミニウムを主とした合金のＩＤＴ電極を配置すると共に、該ＩＤＴ電極を覆うようにＳｉＯ_２膜を付着して構成したＳＨ型弾性表面波デバイスであって、 前記ＳｉＯ_２膜の規格化膜厚を１．７％から３．０％に範囲に設定してＳＨ型弾性表面波デバイスを構成する。
請求項２の発明は、オイラー角（０°，１１０°〜１５０°，９０°±２°）の水晶基板上に２つのアルミニウムを主とした合金のＩＤＴ電極を近接配置すると共に、該ＩＤＴ電極の両側にグレーティング反射器を配設し、これらの電極を覆うようにＳｉＯ_２膜を付着して構成したＳＨ型弾性表面波デバイスであって、前記ＳｉＯ_２膜の規格化膜厚を１．７％から３．０％に範囲に設定してＳＨ型弾性表面波デバイスを構成する。
請求項３の発明は、オイラー角（０°，１１０°〜１５０°，９０°±２°）の水晶基板上に３つのアルミニウムを主とした合金のＩＤＴ電極を近接配置すると共に、該ＩＤＴ電極の両側にグレーティング反射器を配設し、これらの電極を覆うようにＳｉＯ_２膜を付着して構成したＳＨ型弾性表面波デバイスであって、前記ＳｉＯ_２膜の規格化膜厚を１．７％から３．０％に範囲に設定してＳＨ型弾性表面波デバイスを構成する。 The invention according to claim 1 of the surface acoustic wave device according to the present invention is an alloy composed mainly of at least one aluminum on a quartz substrate having an Euler angle (0 °, 110 ° to 150 °, 90 ° ± 2 °). An SH type surface acoustic wave device having an IDT electrode and an SiO ₂ film attached so as to cover the IDT electrode, wherein the normalized film thickness of the SiO ₂ film is 1.7% to 3. An SH type surface acoustic wave device is configured by setting the range to 0%.
In the invention of claim 2, two IDT electrodes made of an alloy mainly composed of aluminum are arranged close to each other on a quartz substrate having an Euler angle (0 °, 110 ° to 150 °, 90 ° ± 2 °), and the IDT electrode 1 is an SH type surface acoustic wave device in which a grating reflector is disposed on both sides of the substrate and an SiO ₂ film is attached so as to cover these electrodes, and the normalized film thickness of the SiO ₂ film is 1.7. The SH type surface acoustic wave device is configured by setting the range from% to 3.0%.
According to the invention of claim 3, three IDT electrodes made mainly of aluminum are arranged close to each other on a quartz substrate having an Euler angle (0 °, 110 ° to 150 °, 90 ° ± 2 °), and the IDT electrode 1 is an SH type surface acoustic wave device in which a grating reflector is disposed on both sides of the substrate and an SiO ₂ film is attached so as to cover these electrodes, and the normalized film thickness of the SiO ₂ film is 1.7. The SH type surface acoustic wave device is configured by setting the range from% to 3.0%.

本発明に係るＳＨ型縦結合二重モードＳＡＷフィルタは、ＳＨ型弾性表面を用いるので、高周波に適すると共に広帯域のパスバンドが得られるのみならず、電極パターン上に付着するＳｉＯ_２膜を適切に設定することにより、レイリー波とほぼ同等な２次温度係数が得られるという利点がある。 Since the SH type longitudinally coupled double mode SAW filter according to the present invention uses an SH type elastic surface, it is suitable not only for high frequency but also for obtaining a wide band pass band, and appropriately applying an SiO ₂ film adhering to the electrode pattern. By setting, there is an advantage that a secondary temperature coefficient almost equal to the Rayleigh wave can be obtained.

図１は本発明に係るＳＨ型弾性表面波を用いた縦結合二重モードＳＡＷフィルタの実施の形態を示す平面図であって、オイラー角(０°,１２６°，９０°)のＳＴカット水晶基板１の主表面上にＳＨ型弾性表面波の伝搬方向（Ｚ’軸）に沿って２つのＩＤＴ電極２、３を近接配置すると共に、該ＩＤＴ電極２、３の両側に反射器４ａ、４ｂを配設して縦結合二重モードＳＡＷフィルタを形成する。ＩＤＴ電極２、３はそれぞれ互いに間挿し合う複数本の電極指を有する一対の櫛形電極により形成され、ＩＤＴ電極２の一方の櫛形電極は入力端子ＩＮに接続すると共に、他方の櫛形電極は接地する。さらに、ＩＤＴ電極３の一方の櫛形電極は出力端子ＯＵＴに接続すると共に、他方の櫛形電極は接地する。そして、該ＩＤＴ電極２、３及び反射器４ａ、４ｂの全面を覆うようにＳｉＯ_２膜を付着して、ＳＨ波型縦結合二重モードＳＡＷフィルタを構成する。 FIG. 1 is a plan view showing an embodiment of a longitudinally coupled double mode SAW filter using SH type surface acoustic waves according to the present invention, and is an ST cut crystal having Euler angles (0 °, 126 °, 90 °). Two IDT electrodes 2 and 3 are disposed close to each other along the propagation direction (Z ′ axis) of the SH type surface acoustic wave on the main surface of the substrate 1, and reflectors 4 a and 4 b are provided on both sides of the IDT electrodes 2 and 3. To form a longitudinally coupled double mode SAW filter. The IDT electrodes 2 and 3 are each formed by a pair of comb electrodes having a plurality of electrode fingers interleaved with each other, and one comb electrode of the IDT electrode 2 is connected to the input terminal IN and the other comb electrode is grounded. . Further, one comb electrode of the IDT electrode 3 is connected to the output terminal OUT, and the other comb electrode is grounded. Then, an SiO ₂ film is attached so as to cover the entire surfaces of the IDT electrodes 2 and 3 and the reflectors 4a and 4b, thereby forming an SH wave type longitudinally coupled double mode SAW filter.

図１に示した電極パターンを用い、オイラー角(０°,１２６°，９０°)のＳＴカット水晶基板１上に、ＩＤＴ電極２、３の対数をそれぞれ７０対、反射器４ａ、４ｂの本数をそれぞれ３６０本、ライン占有率（ライン幅ＬとスペースＳとの和に対するライン幅の比）を５０％、交差幅を１００λ、電極材料はアルミニウムを主成分とし、その規格化膜厚（Ｈ／λ）を２．２％とし、電極パターン上全面にＳｉＯ_２膜５を付着してＳＨ波型縦結合二重モードＳＡＷフィルタを構成した。
図２は、このＳＨ波型縦結合二重モードＳＡＷフィルタの周波数温度特性を測定し、ＳｉＯ_２膜の膜厚ｈ（％λ）と、周波数温度特性（負の２次曲線）の２次温度係数β（×１０^−８／℃^２）との関係を示す曲線である。図２から明らかなように、ＳｉＯ_２膜の膜厚ｈ（％λ）が厚くなるに応じて２次温度係数βの絶対値が小さくなり、膜厚ｈ（％λ）が２．０近傍でほぼ一定値（約−３×１０^−８／℃^２）になり、膜厚ｈ（％λ）が３．０辺りまでほぼ同じ値となる。このように、電極パターン上にＳｉＯ_２膜を付着して構成したＳＨ型縦結合二重モードＳＡＷフィルタは、高周波、広帯域のＳＡＷフィルタが実現できると共に、ＳｉＯ_２膜を適切に設定すればレイリーはとほぼ同等な２次温度係数が得られることが判明した。
なお、ＳｉＯ_２膜の膜厚ｈ（％λ）を３％より厚くすると、ＳＨ波型縦結合二重モードＳＡＷフィルタの損失が次第に大きくなるため、２次温度係数としては良好であるものの上限値としては３％程度が適当である。 Using the electrode pattern shown in FIG. 1, 70 pairs of IDT electrodes 2 and 3 and the number of reflectors 4a and 4b are provided on an ST cut quartz substrate 1 with Euler angles (0 °, 126 ° and 90 °), respectively. , Line occupation ratio (ratio of line width to sum of line width L and space S) 50%, intersection width 100λ, electrode material mainly composed of aluminum, and its normalized film thickness (H / λ) was set to 2.2%, and an SiO ₂ film 5 was deposited on the entire surface of the electrode pattern to constitute an SH wave type longitudinally coupled double mode SAW filter.
FIG. 2 shows the frequency temperature characteristics of this SH wave type longitudinally coupled double mode SAW filter. The film thickness h (% λ) of the SiO ₂ film and the secondary temperature of the frequency temperature characteristics (negative quadratic curve). it is a curve showing the relationship between the coefficient ^{β (× 10 -8 / ℃ 2} ). As is clear from FIG. 2, as the film thickness h (% λ) of the SiO ₂ film increases, the absolute value of the secondary temperature coefficient β decreases, and the film thickness h (% λ) is around 2.0. The value is substantially constant (about −3 × 10 ⁻⁸ / ° C. ² ), and the film thickness h (% λ) is substantially the same up to about 3.0. As described above, the SH-type longitudinally coupled double mode SAW filter configured by attaching the SiO ₂ film on the electrode pattern can realize a high-frequency, broadband SAW filter, and if the SiO ₂ film is appropriately set, the Rayleigh can be achieved. It was found that a secondary temperature coefficient almost equivalent to
Note that when the film thickness h (% λ) of the SiO ₂ film is made larger than 3%, the loss of the SH wave type longitudinally coupled double mode SAW filter gradually increases. As a result, about 3% is appropriate.

以上ではＳＨ型縦結合二重モードＳＡＷフィルタのみを説明したが、１次と３次モードを用いたＳＨ型１次−３次縦結合二重モードＳＡＷフィルタ、ＩＤＴ電極と２つの反射器とで構成するＳＨ型共振子等に適用できることは説明するまでもない。   In the above description, only the SH type longitudinally coupled double mode SAW filter has been described. However, the SH type first and third order longitudinally coupled double mode SAW filter using the first and third order modes, an IDT electrode and two reflectors. Needless to say, the present invention can be applied to the SH resonators and the like.

本発明に係るＳＨ型縦結合二重モードＳＡＷフィルタの構成を示した概略平面図である。1 is a schematic plan view showing the configuration of an SH type longitudinally coupled double mode SAW filter according to the present invention. ＳｉＯ_２膜の膜厚ｈと、周波数温度特性の２次温度係数βとの関係を示す曲線である。And the thickness h of the SiO ₂ film is a curve showing the relationship between the beta 2-order temperature coefficient of the frequency temperature characteristic. 従来の横結合二重モードＳＡＷフィルタの構成を示す平面図である。It is a top view which shows the structure of the conventional horizontal coupling double mode SAW filter. 従来の縦結合二重モードＳＡＷフィルタの構成を示す平面図である。It is a top view which shows the structure of the conventional longitudinal coupling double mode SAW filter.

符号の説明Explanation of symbols

１ 圧電基板
２、３ ＩＤＴ電極
４ａ、４ｂ グレーティング反射器
５ ＳｉＯ_２膜


First piezoelectric substrate 2,3 IDT electrodes 4a, 4b grating reflectors 5 SiO ₂ film

Claims (3)

オイラー角（０°，１１０°〜１５０°，９０°±２°）の水晶基板上に少なくともの１つのアルミニウムを主とした合金のＩＤＴ電極を配置すると共に、該ＩＤＴ電極を覆うようにＳｉＯ_２膜を付着して構成したＳＨ型弾性表面波デバイスであって、
前記ＳｉＯ_２膜の規格化膜厚を１．７％から３．０％に範囲に設定することを特徴とするＳＨ型弾性表面波デバイス。 An IDT electrode made of at least one aluminum-based alloy is disposed on a quartz substrate having an Euler angle (0 °, 110 ° to 150 °, 90 ° ± 2 °), and SiO ₂ is covered so as to cover the IDT electrode. An SH type surface acoustic wave device configured by attaching a film,
An SH type surface acoustic wave device, wherein the normalized film thickness of the SiO ₂ film is set in a range from 1.7% to 3.0%. オイラー角（０°，１１０°〜１５０°，９０°±２°）の水晶基板上に２つのアルミニウムを主とした合金のＩＤＴ電極を近接配置すると共に、該ＩＤＴ電極の両側にグレーティング反射器を配設し、これらの電極を覆うようにＳｉＯ_２膜を付着して構成したＳＨ型弾性表面波デバイスであって、
前記ＳｉＯ_２膜の規格化膜厚を１．７％から３．０％に範囲に設定することを特徴とするＳＨ型弾性表面波デバイス。 Two IDT electrodes made mainly of aluminum are arranged close to each other on a quartz substrate with Euler angles (0 °, 110 ° to 150 °, 90 ° ± 2 °), and grating reflectors are provided on both sides of the IDT electrode. An SH type surface acoustic wave device that is arranged and configured by adhering a SiO ₂ film so as to cover these electrodes,
An SH type surface acoustic wave device, wherein the normalized film thickness of the SiO ₂ film is set in a range from 1.7% to 3.0%. オイラー角（０°，１１０°〜１５０°，９０°±２°）の水晶基板上に３つのアルミニウムを主とした合金のＩＤＴ電極を近接配置すると共に、該ＩＤＴ電極の両側にグレーティング反射器を配設し、これらの電極を覆うようにＳｉＯ_２膜を付着して構成したＳＨ型弾性表面波デバイスであって、
前記ＳｉＯ_２膜の規格化膜厚を１．７％から３．０％に範囲に設定することを特徴とするＳＨ型弾性表面波デバイス。




Three aluminum IDT electrodes are arranged close to each other on a Euler angle (0 °, 110 ° to 150 °, 90 ° ± 2 °) quartz substrate, and grating reflectors are provided on both sides of the IDT electrode. An SH type surface acoustic wave device that is arranged and configured by adhering a SiO ₂ film so as to cover these electrodes,
An SH type surface acoustic wave device, wherein the normalized film thickness of the SiO ₂ film is set in a range from 1.7% to 3.0%.

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