JP4270232B2 - Piezoelectric device substrate manufacturing method, piezoelectric device substrate, and surface acoustic wave device using the same - Google Patents

Piezoelectric device substrate manufacturing method, piezoelectric device substrate, and surface acoustic wave device using the same Download PDF

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JP4270232B2
JP4270232B2 JP2006193317A JP2006193317A JP4270232B2 JP 4270232 B2 JP4270232 B2 JP 4270232B2 JP 2006193317 A JP2006193317 A JP 2006193317A JP 2006193317 A JP2006193317 A JP 2006193317A JP 4270232 B2 JP4270232 B2 JP 4270232B2
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守▲奇▼ 王
聡 宇田
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Mitsubishi Materials Corp
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Description

本発明は、ＳＡＷフィルタ等に好適な圧電デバイス用基板の製造方法と圧電デバイス用基板、及びこれを用いた表面弾性波デバイスに関する。   The present invention relates to a piezoelectric device substrate manufacturing method suitable for a SAW filter or the like, a piezoelectric device substrate, and a surface acoustic wave device using the same.

近年、Ｌａ3Ｇａ5ＳｉＯ14（Langasite:ランガサイト）単結晶は、温度による弾性波伝搬速度、周波数の変化率が小さく、圧電性の大小を表す電気機械結合係数（電気エネルギーと機械エネルギーの相互変換効率を示す係数）が大きいことから、表面弾性波（Surface Acoustic Wave:ＳＡＷ）フィルタ等の圧電デバイス用の基板材料として研究が行われている（例えば、H.Takeda,K.Shimamura,V.I.Chani,T.Fukuda,Effect of starting melt composition on crystal growth of La3Ga5SiO14,J.Crystal Growth 197(1999)204.等）。すなわち、このランガサイト単結晶は、水晶と同等の温度特性を持ち、しかも電気機械結合係数が水晶の約３倍あり、携帯電話等に多用されているＳＡＷフィルタの広帯域化と小型化を図ることが可能になる。例えば、特許文献１にランガサイト単結晶を用いた表面弾性波デバイスが記載されている。
従来、このランガサイト単結晶を育成するには、化学量論比の組成に基づいた原料ペレットを融解して単結晶を育成していた。
特開平１０−１２６２０９号公報 In recent years, La 3 Ga 5 SiO 14 (Langasite) single crystal has a small elastic wave propagation velocity and frequency change rate due to temperature, and an electromechanical coupling coefficient (reciprocal between electrical energy and mechanical energy) representing the magnitude of piezoelectricity. Since the coefficient indicating the conversion efficiency is large, research has been conducted on substrate materials for piezoelectric devices such as surface acoustic wave (SAW) filters (for example, H. Takeda, K. Shimamura, VIChani, T. Fukuda, Effect of starting melt composition on crystal growth of La 3 Ga 5 SiO 14 , J. Crystal Growth 197 (1999) 204.). In other words, this Langasite single crystal has the same temperature characteristics as quartz, and has an electromechanical coupling coefficient of about three times that of quartz, so that the bandwidth and size of SAW filters widely used in mobile phones and the like can be reduced. Is possible. For example, Patent Document 1 describes a surface acoustic wave device using a langasite single crystal.
Conventionally, in order to grow this langasite single crystal, the single crystal was grown by melting the raw material pellets based on the composition of the stoichiometric ratio.
JP-A-10-126209

しかしながら、化学量論的組成等の従来用いられている組成でランガサイト単結晶を育成すると、結晶には二次相が出やすく、結晶が割れやすくなるという不都合がある。また、二次相の発生を抑制するために成長速度をかなり低い値にしなければならなく、生産効率が悪くなってしまう問題があった。さらに、ランガサイト単結晶を構成する原子のうち、Ｇａは揮発し易い性質を有するため、組成によっては高い揮発性のために安定した引上成長が難しいという不都合があった。   However, when a Langasite single crystal is grown with a conventionally used composition such as a stoichiometric composition, there is a disadvantage that a secondary phase is likely to appear in the crystal and the crystal is likely to break. Further, in order to suppress the generation of the secondary phase, the growth rate has to be set to a considerably low value, which causes a problem that the production efficiency is deteriorated. Furthermore, among the atoms constituting the langasite single crystal, Ga has the property of being easily volatilized. Therefore, depending on the composition, there is a disadvantage that stable pulling growth is difficult due to high volatility.

本発明は、前述の課題に鑑みてなされたもので、二次相が発生し難く、さらにＧａの揮発性の影響が少ない圧電デバイス用基板の製造方法と圧電デバイス用基板、及びこれを用いた表面弾性波デバイスを提供することを目的とする。   The present invention has been made in view of the above-described problems, and a piezoelectric device substrate, a piezoelectric device substrate, and a method for producing a piezoelectric device substrate, which are less likely to generate a secondary phase and have less Ga volatility, and the same. An object of the present invention is to provide a surface acoustic wave device.

本発明者らは、ランガサイト単結晶の製造技術について研究を行ってきた結果、二次相がほとんど存在しない組成条件を見出すことができた。さらには、Ｇａの揮発性の影響が少なく、安定した成長が可能な組成条件を見出すことができた。したがって、本発明は、この知見に基づいた技術であり、前記課題を解決するために以下の構成を採用した。   As a result of studying the manufacturing technology of a langasite single crystal, the present inventors have found a composition condition in which almost no secondary phase exists. Furthermore, it was possible to find a composition condition that is less affected by the volatility of Ga and enables stable growth. Therefore, the present invention is a technique based on this finding, and the following configuration is adopted in order to solve the above problems.

すなわち、本発明の圧電デバイス用基板の製造方法は、ランガサイト単結晶を育成して圧電デバイス用基板に加工する圧電デバイス用基板の製造方法であって、添付図面１に示す点Ａ（Ｌａ ２ Ｏ ３ が４７．９８重量％、Ｇａ ２ Ｏ ３ が４６．３２重量％、ＳｉＯ ２ が５．７０重量％）、点Ｅ（Ｌａ ２ Ｏ ３ が４７．５０重量％、Ｇａ ２ Ｏ ３ が４６．３２重量％、ＳｉＯ ２ が６．１８重量％）、点Ｆ（Ｌａ ２ Ｏ ３ が４７．５０重量％、Ｇａ ２ Ｏ ３ が４６．００重量％、ＳｉＯ ２ が６．５０重量％）で囲まれる組成範囲、又は、点Ｅ（Ｌａ ２ Ｏ ３ が４７．５０重量％、Ｇａ ２ Ｏ ３ が４６．３２重量％、ＳｉＯ ２ が６．１８重量％）、点Ｆ（Ｌａ ２ Ｏ ３ が４７．５０重量％、Ｇａ ２ Ｏ ３ が４６．００重量％、ＳｉＯ ２ が６．５０重量％）、点Ｇ（Ｌａ ２ Ｏ ３ が４７．９８重量％、Ｇａ ２ Ｏ ３ が４６．００重量％、ＳｉＯ ２ が６．０２重量％）で囲まれる組成範囲から、点Ａ１（Ｌａ２Ｏ３が４７．８１重量％、Ｇａ２Ｏ３が４６．５０重量％、ＳｉＯ２が５．６９重量％）、点Ｂ１（Ｌａ２Ｏ３が４７．９７重量％、Ｇａ２Ｏ３が４６．２６重量％、ＳｉＯ２が５．７７重量％）、点Ｃ１（Ｌａ２Ｏ３が４８．０４重量％、Ｇａ２Ｏ３が４６．５０重量％、ＳｉＯ２が５．４６重量％）で囲まれる組成範囲を除外した組成範囲内で秤量してルツボ内で融解させ、該ルツボ内からランガサイトの単結晶を引き上げ育成することを特徴とする。 That is, the manufacturing method of the substrate for the piezoelectric device of the present invention is a method for manufacturing a substrate for a piezoelectric device for processing a substrate for the piezoelectric device by growing a langasite single crystal, the point shown in the accompanying drawings 1 A (La 2 O 3 is 47.98 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 5.70 wt%), point E (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 46 .32 wt%, SiO 2 6.18 wt%), point F (La 2 O 3 47.50 wt%, Ga 2 O 3 46.00 wt%, SiO 2 6.50 wt%). Composition range enclosed, or point E (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 6.18 wt%), point F (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 46.00 wt%, SiO 2 6.5 Wt%), the point G (La 2 O 3 is 47.98 wt%, Ga 2 O 3 is 46.00 wt%, a composition range in which SiO 2 is surrounded by a 6.02 wt%), the point A1 (La 2 O 3 is 47.81 wt%, Ga 2 O 3 is 46.50 wt%, SiO 2 is 5.69 wt%, point B1 (La 2 O 3 is 47.97 wt%, Ga 2 O 3 is 46 .26 wt%, SiO 2 5.77 wt%), point C1 (La 2 O 3 48.04 wt%, Ga 2 O 3 46.50 wt%, SiO 2 5.46 wt%) melted in a crucible and weighed in the composition ranges excluding a composition range surrounded, characterized by pulling a single crystal is grown in the langasite from the crucible.

また、本発明の圧電デバイス用基板は、ランガサイトの単結晶で形成された圧電デバイス用基板であって、添付図面１に示す点Ａ（Ｌａ ２ Ｏ ３ が４７．９８重量％、Ｇａ ２ Ｏ ３ が４６．３２重量％、ＳｉＯ ２ が５．７０重量％）、点Ｅ（Ｌａ ２ Ｏ ３ が４７．５０重量％、Ｇａ ２ Ｏ ３ が４６．３２重量％、ＳｉＯ ２ が６．１８重量％）、点Ｆ（Ｌａ ２ Ｏ ３ が４７．５０重量％、Ｇａ ２ Ｏ ３ が４６．００重量％、ＳｉＯ ２ が６．５０重量％）で囲まれる組成範囲、又は、点Ｅ（Ｌａ ２ Ｏ ３ が４７．５０重量％、Ｇａ ２ Ｏ ３ が４６．３２重量％、ＳｉＯ ２ が６．１８重量％）、点Ｆ（Ｌａ ２ Ｏ ３ が４７．５０重量％、Ｇａ ２ Ｏ ３ が４６．００重量％、ＳｉＯ ２ が６．５０重量％）、点Ｇ（Ｌａ ２ Ｏ ３ が４７．９８重量％、Ｇａ ２ Ｏ ３ が４６．００重量％、ＳｉＯ ２ が６．０２重量％）で囲まれる組成範囲から、点Ａ１（Ｌａ２Ｏ３が４７．８１重量％、Ｇａ２Ｏ３が４６．５０重量％、ＳｉＯ２が５．６９重量％）、点Ｂ１（Ｌａ２Ｏ３が４７．９７重量％、Ｇａ２Ｏ３が４６．２６重量％、ＳｉＯ２が５．７７重量％）、点Ｃ１（Ｌａ２Ｏ３が４８．０４重量％、Ｇａ２Ｏ３が４６．５０重量％、ＳｉＯ２が５．４６重量％）で囲まれる組成範囲を除外した組成範囲内で秤量してルツボ内で融解させ、該ルツボ内から引き上げ育成された単結晶であることを特徴とする。 The piezoelectric device substrate of the present invention is a piezoelectric device substrate formed of a single crystal of langasite, points illustrated in the accompanying drawings 1 A (La 2 O 3 is 47.98 wt%, Ga 2 O 3 46.32 wt%, SiO 2 is 5.70 wt%), point E (La 2 O 3 47.50 wt%, Ga 2 O 3 46.32 wt%, SiO 2 is 6.18 wt %), Point F (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 46.00 wt%, SiO 2 is 6.50 wt%), or point E (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 6.18 wt%), the point F (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 46 .00 wt%, SiO 2 is 6.50 wt%), the point G (La 2 O 3 is 47.98 wt% Ga 2 O 3 is 46.00 wt%, a composition range in which SiO 2 is surrounded by a 6.02 wt%), the point A1 (La 2 O 3 is 47.81 wt%, Ga 2 O 3 is 46.50 weight %, SiO 2 5.69 wt%), point B1 (La 2 O 3 47.97 wt%, Ga 2 O 3 46.26 wt%, SiO 2 5.77 wt%), point C1 ( La 2 O 3 is 48.04 wt%, Ga 2 O 3 is 46.50 wt%, SiO 2 is 5.46 wt%) and weighed within the composition range and melted in the crucible And a single crystal grown from the inside of the crucible.

また、本発明の表面弾性波デバイスは、引き上げにより育成されたランガサイトの単結晶で形成された圧電デバイス用基板であって、前記ランガサイトは、添付図面１に示す点ａ（Ｌａ ２ Ｏ ３ が４７．９８重量％、Ｇａ ２ Ｏ ３ が４６．３２重量％、ＳｉＯ ２ が５．７０重量％）、点ｅ（Ｌａ ２ Ｏ ３ が４７．５２重量％、Ｇａ ２ Ｏ ３ が４６．３２重量％、ＳｉＯ ２ が６．１６重量％）、点ｆ（Ｌａ ２ Ｏ ３ が４７．５１重量％、Ｇａ ２ Ｏ ３ が４６．０１重量％、ＳｉＯ ２ が６．４８重量％）で囲まれる組成範囲、又は、点ｅ（Ｌａ ２ Ｏ ３ が４７．５２重量％、Ｇａ ２ Ｏ ３ が４６．３２重量％、ＳｉＯ ２ が６．１６重量％）、点ｆ（Ｌａ ２ Ｏ ３ が４７．５１重量％、Ｇａ ２ Ｏ ３ が４６．０１重量％、ＳｉＯ ２ が６．４８重量％）、点ｇ（Ｌａ ２ Ｏ ３ が４７．９８重量％、Ｇａ ２ Ｏ ３ が４６．０２重量％、ＳｉＯ ２ が６．００重量％）で囲まれる組成範囲から、点ａ１（Ｌａ２Ｏ３が４７．８２重量％、Ｇａ２Ｏ３が４６．５０重量％、ＳｉＯ２が５．６８重量％）、点ｂ１（Ｌａ２Ｏ３が４７．９７重量％、Ｇａ２Ｏ３が４６．２７重量％、ＳｉＯ２が５．７６重量％）、点ｃ１（Ｌａ２Ｏ３が４８．０３重量％、Ｇａ２Ｏ３が４６．４９重量％、ＳｉＯ２が５．４８重量％）で囲まれる組成範囲を除外した組成範囲内の単結晶であることを特徴とする。 The surface acoustic wave device of the present invention, there is provided a piezoelectric device substrate formed of a single crystal of the grown langasite by pulling, the langasite are that shown in the accompanying drawings 1 a (La 2 O 3 There 47.98 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 5.70 wt%), the point e (La 2 O 3 is 47.52 wt%, Ga 2 O 3 is 46.32 % F , SiO 2 is 6.16 wt%), point f (La 2 O 3 is 47.51 wt%, Ga 2 O 3 is 46.01 wt%, SiO 2 is 6.48 wt%) Composition range or point e (La 2 O 3 is 47.52 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 6.16 wt%), point f (La 2 O 3 is 47.3 % by weight) . 51 wt%, Ga 2 O 3 is 46.01 wt%, SiO 2 is 6.48 fold %), The point g (La 2 O 3 is 47.98 wt%, Ga 2 O 3 is 46.02 wt%, a composition range in which SiO 2 is surrounded by a 6.00 wt%), the point a1 (La 2 O 3 47.82 wt%, Ga 2 O 3 46.50 wt%, SiO 2 is 5.68 wt%), the point b1 (La 2 O 3 47.97 wt%, Ga 2 O 3 is 46. 27 wt%, SiO 2 5.76 wt%), surrounded by point c1 (La 2 O 3 48.03 wt%, Ga 2 O 3 46.49 wt%, SiO 2 5.48 wt%) It is a single crystal within the composition range excluding the composition range.

これらの圧電デバイス用基板の製造方法及び圧電デバイス用基板では、後述する実験結果に基づいて、Ｌａ3Ｇａ5ＳｉＯ14の原料であるＬａ2Ｏ3、Ｇａ2Ｏ3及びＳｉＯ2のそれぞれ組成範囲を上記範囲内で秤量してルツボ内で融解させ、該ルツボ内からＬａ3Ｇａ5ＳｉＯ14の単結晶を引き上げ育成し、またＬａ3Ｇａ5ＳｉＯ14が、Ｌａ2Ｏ3、Ｇａ2Ｏ3及びＳｉＯ2が上記組成範囲内の単結晶であるので、二次相の発生が極めて少ない高品質なＬａ3Ｇａ5ＳｉＯ14単結晶が得られるとともに、バラツキの少ない表面弾性波伝搬速度及び均一な中心周波数を有する基板が得られる。 In these piezoelectric device substrate manufacturing methods and piezoelectric device substrates, the composition ranges of La 2 O 3 , Ga 2 O 3 and SiO 2 , which are raw materials of La 3 Ga 5 SiO 14 , are based on the experimental results described later. the melted in a crucible and weighed in the above range, then pulling a single crystal is grown of La 3 Ga 5 SiO 14 from the crucible, also La 3 Ga 5 SiO 14 is, La 2 O 3, Ga 2 O 3 And SiO 2 is a single crystal within the above composition range, so that a high-quality La 3 Ga 5 SiO 14 single crystal with very little generation of secondary phase can be obtained, and the surface acoustic wave propagation velocity and uniform variation can be reduced. A substrate having a center frequency is obtained.

さらに、本発明の圧電デバイス用基板の製造方法は、添付図面１に示す点Ａ（Ｌａ2Ｏ3が４７．９８重量％、Ｇａ2Ｏ3が４６．３２重量％、ＳｉＯ2が５．７０重量％）、点Ｂ（Ｌａ2Ｏ3が４８．５０重量％、Ｇａ2Ｏ3が４６．３２重量％、ＳｉＯ2が５．１８重量％）、点Ｃ（Ｌａ2Ｏ3が４８．５０重量％、Ｇａ2Ｏ3が４７．５０重量％、ＳｉＯ2が４．００重量％）、点Ｄ（Ｌａ2Ｏ3が４７．５０重量％、Ｇａ2Ｏ3が４７．５０重量％、ＳｉＯ2が５．００重量％）、点Ｅ（Ｌａ2Ｏ3が４７．５０重量％、Ｇａ2Ｏ3が４６．３２重量％、ＳｉＯ2が６．１８重量％）で囲まれる組成範囲内で秤量してルツボ内で融解させ、該ルツボ内からＬａ3Ｇａ5ＳｉＯ14の単結晶を引き上げ育成することが好ましい。 Furthermore, the method for manufacturing a substrate for a piezoelectric device of the present invention is based on the point A (La 2 O 3 is 47.98 wt%, Ga 2 O 3 is 46.32 wt%, and SiO 2 is 5.70 shown in the accompanying drawings. %), Point B (La 2 O 3 is 48.50% by weight, Ga 2 O 3 is 46.32% by weight, SiO 2 is 5.18% by weight), point C (La 2 O 3 is 48.50%). %, Ga 2 O 3 is 47.50%, SiO 2 is 4.00% by weight), point D (La 2 O 3 is 47.50%, Ga 2 O 3 is 47.50%, SiO 2 2 is 5.00% by weight), and within a composition range surrounded by point E (La 2 O 3 is 47.50% by weight, Ga 2 O 3 is 46.32% by weight, SiO 2 is 6.18% by weight). It is preferable to weigh and melt in a crucible, and pull up and grow a single crystal of La 3 Ga 5 SiO 14 from the crucible.

また、本発明の圧電デバイス用基板は、添付図面１に示す点Ａ（Ｌａ2Ｏ3が４７．９８重量％、Ｇａ2Ｏ3が４６．３２重量％、ＳｉＯ2が５．７０重量％）、点Ｂ（Ｌａ2Ｏ3が４８．５０重量％、Ｇａ2Ｏ3が４６．３２重量％、ＳｉＯ2が５．１８重量％）、点Ｃ（Ｌａ2Ｏ3が４８．５０重量％、Ｇａ2Ｏ3が４７．５０重量％、ＳｉＯ2が４．００重量％）、点Ｄ（Ｌａ2Ｏ3が４７．５０重量％、Ｇａ2Ｏ3が４７．５０重量％、ＳｉＯ2が５．００重量％）、点Ｅ（Ｌａ2Ｏ3が４７．５０重量％、Ｇａ2Ｏ3が４６．３２重量％、ＳｉＯ2が６．１８重量％）で囲まれる組成範囲内で秤量してルツボ内で融解させ、該ルツボ内から引き上げ育成された単結晶であることが好ましい。 Further, the piezoelectric device substrate of the present invention has a point A (La 2 O 3 is 47.98 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 5.70 wt%) shown in the attached drawings 1. , Point B (La 2 O 3 is 48.50 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 5.18 wt%), point C (La 2 O 3 is 48.50 wt%, Ga 2 O 3 47.50 wt%, SiO 2 4.00 wt%), point D (La 2 O 3 47.50 wt%, Ga 2 O 3 47.50 wt%, SiO 2 5 0.000% by weight), point E (La 2 O 3 is 47.50% by weight, Ga 2 O 3 is 46.32% by weight, SiO 2 is 6.18% by weight). It is preferably a single crystal that has been melted in a crucible and pulled up and grown from within the crucible.

また、本発明の圧電デバイス用基板の製造方法は、前記Ｌａ3Ｇａ5ＳｉＯ14が、添付図面１に示す点ａ（Ｌａ2Ｏ3が４７．９８重量％、Ｇａ2Ｏ3が４６．３２重量％、ＳｉＯ2が５．７０重量％）、点ｂ（Ｌａ2Ｏ3が４８．４８重量％、Ｇａ2Ｏ3が４６．３２重量％、ＳｉＯ2が５．２０重量％）、点ｃ（Ｌａ2Ｏ3が４８．４９重量％、Ｇａ2Ｏ3が４７．４９重量％、ＳｉＯ2が４．０２重量％）、点ｄ（Ｌａ2Ｏ3が４７．５２重量％、Ｇａ2Ｏ3が４７．４９重量％、ＳｉＯ2が４．９９重量％）、点ｅ（Ｌａ2Ｏ3が４７．５２重量％、Ｇａ2Ｏ3が４６．３２重量％、ＳｉＯ2が６．１６重量％）で囲まれる組成範囲内の単結晶であることが好ましい。 Further, in the method for manufacturing a piezoelectric device substrate of the present invention, the La 3 Ga 5 SiO 14 is composed of the point a (La 2 O 3 is 47.98 wt%, Ga 2 O 3 is 46.32 shown in the attached drawings 1). % B, SiO 2 5.70 wt%), point b (La 2 O 3 48.48 wt%, Ga 2 O 3 46.32 wt%, SiO 2 5.20 wt%), point c (La 2 O 3 is 48.49 wt%, Ga 2 O 3 is 47.49 wt%, SiO 2 is 4.02 wt%), point d (La 2 O 3 is 47.52 wt%, Ga 2 O 3 47.49 wt%, SiO 2 is 4.99 wt%), the point e (La 2 O 3 47.52 wt%, Ga 2 O 3 46.32 wt%, SiO 2 is 6.16 wt %) Is preferably a single crystal within the composition range.

これらの圧電デバイス用基板の製造方法及び圧電デバイス用基板では、Ｌａ3Ｇａ5ＳｉＯ14の原料であるＬａ2Ｏ3、Ｇａ2Ｏ3及びＳｉＯ2のそれぞれ組成範囲をさらに上記範囲内に限定秤量してルツボ内で融解させ、該ルツボ内からＬａ3Ｇａ5ＳｉＯ14の単結晶を引き上げ育成し、またＬａ3Ｇａ5ＳｉＯ14が、Ｌａ2Ｏ3、Ｇａ2Ｏ3及びＳｉＯ2が上記組成範囲内に限定した単結晶であるので、二次相の発生を抑制するだけでなく、Ｇａ2Ｏ3の高い組成比により、Ｇａの揮発性による成長への影響を極力低減することができる。 In these piezoelectric device substrate manufacturing methods and piezoelectric device substrates, the composition ranges of La 2 O 3 , Ga 2 O 3 and SiO 2 which are raw materials of La 3 Ga 5 SiO 14 are further limited to the above ranges. It melted in a crucible and by pulling a single crystal is grown of La 3 Ga 5 SiO 14 from the crucible, also La 3 Ga 5 SiO 14 is, La 2 O 3, Ga 2 O 3 and SiO 2 is above composition Since the single crystal is limited within the range, not only the generation of the secondary phase is suppressed, but also the influence on the growth due to the volatility of Ga can be reduced as much as possible by the high composition ratio of Ga 2 O 3 .

また、本発明の圧電デバイス用基板は、デバイスが利用する表面上の一定方向に表面弾性波が伝搬したときの伝搬速度のバラツキが１００ｐｐｍ以下にあることが好ましい。
この圧電デバイス用基板では、上記伝搬速度のバラツキが１００ｐｐｍ以下にあるので、ＳＡＷフィルタ特性の均一性を向上させることができる。 In addition, in the piezoelectric device substrate of the present invention, it is preferable that the variation in the propagation speed when the surface acoustic wave propagates in a certain direction on the surface used by the device is 100 ppm or less.
In this piezoelectric device substrate, since the variation in the propagation speed is 100 ppm or less, the uniformity of the SAW filter characteristics can be improved.

本発明の表面弾性波デバイスは、上記本発明の圧電デバイス基板の表面上に表面弾性波を送受信する電極を形成したことを特徴とする。
この表面弾性波デバイスでは、上記本発明の圧電デバイス基板を用いることで、高品質で特性のバラツキが少ないとともに高い信頼性を得ることができる。 The surface acoustic wave device of the present invention is characterized in that an electrode for transmitting and receiving surface acoustic waves is formed on the surface of the piezoelectric device substrate of the present invention.
In this surface acoustic wave device, by using the piezoelectric device substrate of the present invention, high quality and less variation in characteristics and high reliability can be obtained.

本発明によれば、Ｌａ3Ｇａ5ＳｉＯ14の原料であるＬａ2Ｏ3、Ｇａ2Ｏ3及びＳｉＯ2のそれぞれ組成範囲を上述した範囲内で秤量してルツボ内で融解させ、該ルツボ内からＬａ3Ｇａ5ＳｉＯ14の単結晶を引き上げ育成し、またＬａ3Ｇａ5ＳｉＯ14が、Ｌａ2Ｏ3、Ｇａ2Ｏ3及びＳｉＯ2の組成範囲が上述した範囲内の単結晶であるので、二次相の発生が極めて少ない高品質なＬａ3Ｇａ5ＳｉＯ14単結晶が得られ、結晶が割れ難くなると共に、成長速度を低くする必要が無く、生産効率を維持することができる。また、均一な中心周波数及び伝搬速度を有する基板を得ることができる。すなわち、長さ方向及び横方向の組成の均一なランガサイト単結晶を育成でき、この結晶から切り出された圧電デバイス用基板は、その表面弾性波伝搬速度のバラツキが大幅に減少し、弾性波素子性能のバラツキも十分に小さくすることができる。 According to the present invention, each of the composition ranges of La 2 O 3 , Ga 2 O 3 and SiO 2 which are raw materials of La 3 Ga 5 SiO 14 are weighed within the ranges described above and melted in the crucible, and pulling a single crystal is grown of La 3 Ga 5 SiO 14 from and La 3 Ga 5 SiO 14 is, because La 2 O 3, a composition range in the Ga 2 O 3 and the SiO 2 is a single crystal in the above-described range As a result, a high-quality La 3 Ga 5 SiO 14 single crystal with very few secondary phases can be obtained, the crystal is difficult to break, and it is not necessary to lower the growth rate, so that the production efficiency can be maintained. In addition, a substrate having a uniform center frequency and propagation speed can be obtained. That is, a Langasite single crystal having a uniform composition in the length direction and the transverse direction can be grown, and the variation of the surface acoustic wave propagation speed of the substrate for a piezoelectric device cut out from this crystal is greatly reduced. The variation in performance can be sufficiently reduced.

以下、本発明に係る圧電デバイス用基板の製造方法と圧電デバイス用基板、及びこれを用いた表面弾性波デバイスの一実施形態を、図１から図３を参照しながら説明する。   DESCRIPTION OF EMBODIMENTS Hereinafter, a piezoelectric device substrate manufacturing method, a piezoelectric device substrate, and a surface acoustic wave device using the same according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3.

本実施形態の圧電デバイス基板及び表面弾性波デバイスを製造するには、まず、図１に示す第１の組成範囲、すなわち、図１に示す点Ａ（Ｌａ2Ｏ3が４７．９８重量％、Ｇａ2Ｏ3が４６．３２重量％、ＳｉＯ2が５．７０重量％）、
点Ｂ（Ｌａ2Ｏ3が４８．５０重量％、Ｇａ2Ｏ3が４６．３２重量％、ＳｉＯ2が５．１８重量％）、
点Ｃ（Ｌａ2Ｏ3が４８．５０重量％、Ｇａ2Ｏ3が４７．５０重量％、ＳｉＯ2が４．００重量％）、
点Ｄ（Ｌａ2Ｏ3が４７．５０重量％、Ｇａ2Ｏ3が４７．５０重量％、ＳｉＯ2が５．００重量％）、
点Ｅ（Ｌａ2Ｏ3が４７．５０重量％、Ｇａ2Ｏ3が４６．３２重量％、ＳｉＯ2が６．１８重量％）、
点Ｆ（Ｌａ2Ｏ3が４７．５０重量％、Ｇａ2Ｏ3が４６．００重量％、ＳｉＯ2が６．５０重量％）、
点Ｇ（Ｌａ2Ｏ3が４７．９８重量％、Ｇａ2Ｏ3が４６．００重量％、ＳｉＯ2が６．０２重量％）で囲まれる組成範囲内で原料を秤量する。 In order to manufacture the piezoelectric device substrate and the surface acoustic wave device of this embodiment, first, the first composition range shown in FIG. 1, that is, the point A (La 2 O 3 is 47.98% by weight shown in FIG. Ga 2 O 3 is 46.32 wt%, SiO 2 is 5.70 wt%),
Point B (La 2 O 3 is 48.50 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 5.18 wt%),
Point C (La 2 O 3 is 48.50 wt%, Ga 2 O 3 is 47.50 wt%, SiO 2 is 4.00 wt%),
Point D (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 47.50 wt%, SiO 2 is 5.00 wt%),
Point E (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 6.18 wt%),
Point F (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 46.00 wt%, SiO 2 is 6.50 wt%),
The raw materials are weighed within a composition range surrounded by point G (La 2 O 3 is 47.98 wt%, Ga 2 O 3 is 46.00 wt%, SiO 2 is 6.02 wt%).

なお、この組成範囲は、Ｌａ2Ｏ3が４７．５０重量％から４８．５０重量％までとし、Ｇａ2Ｏ3が４６．００重量％から４７．５０重量％までとし、ＳｉＯ2が４．００重量％から６．５０重量％までとした組成範囲内から、Ｌａ2Ｏ3が４７．９８重量％を越えていると共にＧａ2Ｏ3が４６．３２重量％未満の組成範囲を除いた組成範囲である。
次に、これらの原料を振動攪拌機で１時間混合させ、外径１００ｍｍ×６０ｍｍの寸法をもったペレットに成形する。次に、ペレットを電気炉で１２００℃の温度で、１時間空気中で焼成する。 This composition range is such that La 2 O 3 is 47.50 wt% to 48.50 wt%, Ga 2 O 3 is 46.00 wt% to 47.50 wt%, and SiO 2 is 4. The composition excluding the composition range in which La 2 O 3 exceeds 47.98% by weight and Ga 2 O 3 is less than 46.32% by weight from the composition range from 00% to 6.50% by weight. It is a range.
Next, these raw materials are mixed with a vibration stirrer for 1 hour and formed into pellets having a size of an outer diameter of 100 mm × 60 mm. Next, the pellet is fired in air at a temperature of 1200 ° C. for 1 hour in an electric furnace.

結晶の育成は、高周波加熱育成炉において、図２に示すように、イリジウム製のルツボ１を用いて行い。該ルツボ１の外側と上方にアルミナ及びジルコニアの断熱材２を設け、ホットゾーンを形成する。断熱材２の外側には、加熱用の高周波ワークコイル３を設置する。なお、ルツボ１底部には、熱電対４が設置されている。   Crystal growth is performed in a high-frequency heating and growth furnace using an iridium crucible 1 as shown in FIG. An insulating material 2 made of alumina and zirconia is provided outside and above the crucible 1 to form a hot zone. A high-frequency work coil 3 for heating is installed outside the heat insulating material 2. A thermocouple 4 is installed at the bottom of the crucible 1.

育成の際に、ルツボ１の中に焼成されたペレットをチャージし、加熱、融解させて所定温度の融液Ｌとする。そして、ランガサイト（Ｌａ3Ｇａ5ＳｉＯ14）の種結晶Ｓを引き上げ軸５に固定し、所定の回転数と引上速度で融液Ｌからランガサイト単結晶Ｃを育成する。自動直径制御は、引き上げ軸５につながる重量センサ６で検出した結晶の重量変化信号により行う。 During the growth, the baked pellets are charged in the crucible 1 and heated and melted to obtain a melt L at a predetermined temperature. Then, a seed crystal S of langasite (La 3 Ga 5 SiO 14 ) is fixed to the pulling shaft 5, and a langasite single crystal C is grown from the melt L at a predetermined rotation speed and pulling speed. The automatic diameter control is performed based on a crystal weight change signal detected by a weight sensor 6 connected to the pulling shaft 5.

このようにして育成したランガサイト単結晶Ｃ（直径８５ｃｍで直胴部の長さが１９０ｃｍ）は、秤量時の組成範囲と同様の組成範囲内の単結晶となる。すなわち、上記組成範囲の秤量で育成した単結晶は、図１に示す点Ａの組成では点ａ（Ｌａ2Ｏ3が４７．９８重量％、Ｇａ2Ｏ3が４６．３２重量％、ＳｉＯ2が５．７０重量％）の組成となり、点Ｂの組成では点ｂ（Ｌａ2Ｏ3が４８．４８重量％、Ｇａ2Ｏ3が４６．３２重量％、ＳｉＯ2が５．２０重量％）となり、点Ｃの組成では点ｃ（Ｌａ2Ｏ3が４８．４９重量％、Ｇａ2Ｏ3が４７．４９重量％、ＳｉＯ2が４．０２重量％）となり、点Ｄの組成では点ｄ（Ｌａ2Ｏ3が４７．５２重量％、Ｇａ2Ｏ3が４７．４９重量％、ＳｉＯ2が４．９９重量％）となり、点Ｅの組成では点ｅＬａ2Ｏ3が４７．５２重量％、Ｇａ2Ｏ3が４６．３２重量％、ＳｉＯ2が６．１６重量％）となり、点Ｆの組成では点ｆ（Ｌａ2Ｏ3が４７．５１重量％、Ｇａ2Ｏ3が４６．０１重量％、ＳｉＯ2が６．４８重量％）となり、点Ｇの組成では点ｇ（Ｌａ2Ｏ3が４７．９８重量％、Ｇａ2Ｏ3が４６．０２重量％、ＳｉＯ2が６．００重量％）の組成となった。したがって、この単結晶は、図１に示す点ａ〜ｇで囲まれる組成範囲内の単結晶である。これらの組成範囲内におけるランガサイト単結晶には、二次相がほとんど発生していない。 The langasite single crystal C (having a diameter of 85 cm and a length of the straight body portion of 190 cm) grown in this manner is a single crystal having a composition range similar to the composition range at the time of weighing. That is, the single crystal grown by weighing in the above composition range has a composition of a point A shown in FIG. 1 with a point a (La 2 O 3 is 47.98 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 5. In the composition of point B, point b (La 2 O 3 is 48.48% by weight, Ga 2 O 3 is 46.32% by weight, SiO 2 is 5.20% by weight) In the composition of point C, point c (La 2 O 3 is 48.49% by weight, Ga 2 O 3 is 47.49% by weight, SiO 2 is 4.02% by weight). (La 2 O 3 is 47.52 wt%, Ga 2 O 3 is 47.49 wt%, SiO 2 is 4.99 wt%). In the composition of point E, the point eLa 2 O 3 is 47.52 wt%. , Ga 2 O 3 is 46.32 wt%, SiO 2 is 6.16 wt%), and a point f (La 2 O 3 in the composition of the point F 47.51 double %, Ga 2 O 3 is 46.01 wt%, SiO 2 is 6.48 wt%), and the point in the composition of the point G g (La 2 O 3 is 47.98 wt%, Ga 2 O 3 is 46. 02 wt%, SiO 2 6.00 wt%). Therefore, this single crystal is a single crystal within the composition range surrounded by the points a to g shown in FIG. In the langasite single crystal within these composition ranges, almost no secondary phase is generated.

次に、このランガサイト単結晶Ｃは、スライスされて圧電デバイス用基板に加工される。さらに、この圧電デバイス用基板には、図３に示すように、その表面に励振電極（すだれ電極（櫛歯電極））７が形成されてＳＡＷフィルタ（表面弾性波デバイス）８が作製される。
なお、上記圧電デバイス用基板は、表面弾性波音速（表面上を表面弾性波が伝搬したとき、すなわちデバイスが利用する一定方向（励振電極３の対向方向）に伝搬したときの伝搬速度）のバラツキが１００ｐｐｍ以下となっている。 Next, the langasite single crystal C is sliced and processed into a piezoelectric device substrate. Further, as shown in FIG. 3, the substrate for piezoelectric device has an excitation electrode (interdigital electrode (comb electrode)) 7 formed on the surface thereof, and a SAW filter (surface acoustic wave device) 8 is manufactured.
Note that the piezoelectric device substrate has variations in the surface acoustic wave sound velocity (propagation speed when the surface acoustic wave propagates on the surface, that is, when it propagates in a certain direction used by the device (opposite direction of the excitation electrode 3)). Is 100 ppm or less.

次に、本発明に係る圧電デバイス用基板の製造方法と圧電デバイス用基板、及びこれを用いた表面弾性波デバイスを、実施例により図１、図４から図７を参照して具体的に説明する。   Next, a piezoelectric device substrate manufacturing method, a piezoelectric device substrate, and a surface acoustic wave device using the same according to the present invention will be described in detail with reference to FIGS. 1 and 4 to 7. To do.

上記製造方法において、Ｌａ2Ｏ3、Ｇａ2Ｏ3及びＳｉＯ2の組成を変えて圧電デバイス基板を製造し、これらの基板における二次相の発生の有無を調べた実験データを、以下の表１及び図１に示す。なお、図１中のマークは、二次相が発生した場合は■、発生しない場合は□としている。また、図１中のＸ点は、従来の化学量論的組成（Ｌａ2Ｏ3が４８．０４重量％、Ｇａ2Ｏ3が４６．０６重量％、ＳｉＯ2が５．９１重量％）に基づいて育成した単結晶の場合であり、Ｙ点は、上述したJ.Crystal Growth掲載の論文で記載されている組成（Ｌａ2Ｏ3が４７．９９重量％、Ｇａ2Ｏ3が４６．３０重量％、ＳｉＯ2が５．７１重量％）に基づいて育成した単結晶の場合である。 In the above manufacturing method, piezoelectric device substrates were manufactured by changing the composition of La 2 O 3 , Ga 2 O 3 and SiO 2 , and experimental data for examining the occurrence of secondary phases in these substrates were shown in the following table. 1 and FIG. The mark in FIG. 1 is marked with ■ when the secondary phase occurs, and □ when it does not occur. Further, the point X in FIG. 1 shows the conventional stoichiometric composition (La 2 O 3 is 48.04 wt%, Ga 2 O 3 is 46.06 wt%, SiO 2 is 5.91 wt%). This is the case of a single crystal grown based on the Y point, and the Y point is the composition described in the above-mentioned paper published by J. Crystal Growth (La 2 O 3 is 47.9 wt%, Ga 2 O 3 is 46.30). This is a case of a single crystal grown on the basis of wt%, SiO 2 ( 5.71 wt%).

Figure 0004270232
Figure 0004270232

表１及び図１に示すように、上述した組成範囲内の組成で製造した試料番号ＡからＧまでは、二次相が発生しておらず良質な結晶が得られているのに対し、上記組成範囲外の試料（試料番号ＨからＭ）については、二次相が発生してしまっていることがわかる。   As shown in Table 1 and FIG. 1, sample numbers A to G manufactured with compositions in the above-described composition range have no secondary phase and good quality crystals are obtained. It can be seen that a secondary phase has been generated for samples outside the composition range (sample numbers H to M).

また、上記組成範囲のうち、Ｌａ2Ｏ3が４７．９３重量％、Ｇａ2Ｏ3が４６．６６重量％、ＳｉＯ2が５．４１重量％の組成で原料を秤量し、ペレットを作製してルツボ１中にチャージし、直径８５ｃｍ直胴部の長さ１９０ｃｍのランガサイト単結晶Ｃを育成した。そして、このランガサイト単結晶の結晶長さ方向における組成をＩＣＰ分析（Inductive Coupled Plasma:誘導結合プラズマ）で分析した。その結果、表２及び図４、５に示すように、各成分の含有量は、投入組成の±０．０２％以内の誤差で一致した。したがって、上部、中部、下部を通して均一性の良い結晶が得られたことが判明した。さらに、このランガサイト単結晶は、二次相も発生しなかった。 Also, among the above composition ranges, La 2 O 3 is 47.93% by weight, Ga 2 O 3 is 46.66% by weight, and SiO 2 is 5.41% by weight. The crucible 1 was charged to grow a langasite single crystal C having a diameter of 85 cm and a length of 190 cm. The composition of the langasite single crystal in the crystal length direction was analyzed by ICP analysis (Inductive Coupled Plasma). As a result, as shown in Table 2 and FIGS. 4 and 5, the content of each component matched with an error within ± 0.02% of the input composition. Therefore, it was found that crystals with good uniformity were obtained through the upper part, the middle part, and the lower part. Furthermore, this langasite single crystal did not generate a secondary phase.

Figure 0004270232
Figure 0004270232

なお、比較例として、表３及び図６に示すように、原料を従来の化学量論比組成に基づいて秤量し、上記実施例と同様に、結晶を育成した。なお、この結晶の上部（肩部）の形成段階において二次相が発生した。そして、結晶上部から下部にかけて組成の変動が目標含有量の±０．５％であった。この結晶の下部は、弾性波素子として使用できないものであった。   As a comparative example, as shown in Table 3 and FIG. 6, raw materials were weighed based on a conventional stoichiometric composition, and crystals were grown in the same manner as in the above examples. A secondary phase was generated in the formation stage of the upper part (shoulder part) of the crystal. And the variation of the composition from the upper part of the crystal to the lower part was ± 0.5% of the target content. The lower part of this crystal cannot be used as an acoustic wave device.

Figure 0004270232
Figure 0004270232

次に、上記実施例のランガサイト単結晶から５０度回転Ｙ軸のウェハを作製した。このウェハ面内の表面弾性波音速（伝搬速度）のバラツキを調べるために、スパッタによってアルミ電極の励振電極７を形成し、上記実施形態のＳＡＷフィルタ８を作製した。そして、ネットアナライザを用いてＳＡＷフィルタ８の中心周波数ｆcを測定した。この測定では、ＳＡＷフィルタの入力端子に交流信号をかけ、出力端子から出力信号を測定し、周波数走査によってフィルタの出力信号と入力信号の相対振幅の周波数特性を得た。 Next, a 50-degree rotated Y-axis wafer was fabricated from the langasite single crystal of the above example. In order to investigate the variation of the surface acoustic wave sound velocity (propagation velocity) in the wafer surface, the excitation electrode 7 of aluminum electrode was formed by sputtering, and the SAW filter 8 of the above embodiment was produced. Then, to measure the center frequency f c of the SAW filter 8 with a net analyzer. In this measurement, an AC signal was applied to the input terminal of the SAW filter, the output signal was measured from the output terminal, and the frequency characteristics of the relative amplitude of the filter output signal and the input signal were obtained by frequency scanning.

なお、中心周波数ｆcは、この周波数特性のピーク値から通過損失が−１０ｄＢになる通過帯域中心点の周波数である。ここで、表面弾性波音速ｖは、ｖ＝ｆc・２ｄという関係式によって求めることができる。なお、２ｄはＳＡＷフィルタ８の励振電極（すだれ電極）７の周期であり、その寸法の精度は電子顕微鏡で確認されている。こうすることによって、ＳＡＷフィルタの中心周波数から表面弾性波音速を求め、表面弾性波音速の基板面内バラツキを調べることができる。
さらに、結晶の上部、中部、下部からの基板の総合的なバラツキも調べた。その結果、図７に示すように、表面弾性波音速のバラツキが１００ｐｐｍ以下であり、結晶の組成の均一性によるＳＡＷフィルタの特性均一性の向上が判明された。 The center frequency f c is the transmission loss from the peak value of the frequency characteristic is a frequency of the pass band center point to be -10 dB. Here, the surface acoustic wave velocities v can be found by relational expression v = f c · 2d. Note that 2d is the period of the excitation electrode (bending electrode) 7 of the SAW filter 8, and the accuracy of the dimensions is confirmed by an electron microscope. By doing this, the surface acoustic wave sound velocity can be obtained from the center frequency of the SAW filter, and the in-plane variation of the surface acoustic wave sound velocity can be examined.
Furthermore, the total variation of the substrate from the top, middle and bottom of the crystal was also examined. As a result, as shown in FIG. 7, the variation of the surface acoustic wave sound velocity was 100 ppm or less, and it was found that the uniformity of the characteristics of the SAW filter was improved by the uniformity of the crystal composition.

なお、結晶の組成変化が表面弾性波音速のバラツキに与える影響を調べるために、比較例として化学量論比組成に基づいて育成した従来例の結晶を実施例と同様に、圧電デバイス用基板に加工し、ＳＡＷフィルタを作製した。なお、この実験では、結晶上部の透明部しか使わなかった。このＳＡＷフィルタの中心周波数を測定すると、結晶の育成方向の表面弾性波音速バラツキは４００ｐｐｍであり、弾性波素子としてバラツキが大きすぎる結果となった。   In order to investigate the effect of changes in crystal composition on the variation of surface acoustic wave sound velocity, as a comparative example, a conventional crystal grown based on a stoichiometric composition was applied to a piezoelectric device substrate in the same manner as in the examples. The SAW filter was manufactured by processing. In this experiment, only the transparent part above the crystal was used. When the center frequency of this SAW filter was measured, the surface acoustic wave sound speed variation in the crystal growth direction was 400 ppm, and the variation was too large as an acoustic wave device.

すなわち、本発明では、ランガサイトの原料であるＬａ2Ｏ3、Ｇａ2Ｏ3及びＳｉＯ2のそれぞれ組成範囲を上記範囲内で秤量してルツボ１内で融解させ、該ルツボ内からランガサイト単結晶Ｃを引き上げ育成するので、二次相の発生が極めて少なく長さ方向及び横方向（ウェハ面内）の組成の均一な高品質ランガサイト単結晶が得られるとともに、均一な伝搬速度を有する基板が得られる。そして、表面弾性波音速バラツキが１００ｐｐｍ以下の圧電デバイス用基板が得られることから、該基板を用いることにより、ＳＡＷフィルタ特性の均一性が向上して、高品質なデバイスを高歩留まりで得ることができる。 That is, in the present invention, each of the composition ranges of La 2 O 3 , Ga 2 O 3 and SiO 2 which are raw materials of langasite are weighed within the above ranges and melted in the crucible 1, and the langasite single unit is extracted from the crucible. Since the crystal C is pulled up and grown, a high-quality langasite single crystal having a uniform composition in the length direction and the lateral direction (in the wafer plane) can be obtained with very little secondary phase, and a substrate having a uniform propagation speed Is obtained. Since a substrate for a piezoelectric device having a surface acoustic wave sound velocity variation of 100 ppm or less can be obtained, the use of this substrate can improve the uniformity of SAW filter characteristics and provide a high-quality device with a high yield. it can.

なお、Ｇａの揮発性を考慮した場合において、圧電デバイス基板及び表面弾性波デバイスを製造するには、図１に示す第２の組成範囲、すなわち、図１に示す点Ａ（Ｌａ2Ｏ3が４７．９８重量％、Ｇａ2Ｏ3が４６．３２重量％、ＳｉＯ2が５．７０重量％）、
点Ｂ（Ｌａ2Ｏ3が４８．５０重量％、Ｇａ2Ｏ3が４６．３２重量％、ＳｉＯ2が５．１８重量％）、
点Ｃ（Ｌａ2Ｏ3が４８．５０重量％、Ｇａ2Ｏ3が４７．５０重量％、ＳｉＯ2が４．００重量％）、
点Ｄ（Ｌａ2Ｏ3が４７．５０重量％、Ｇａ2Ｏ3が４７．５０重量％、ＳｉＯ2が５．００重量％）、
点Ｅ（Ｌａ2Ｏ3が４７．５０重量％、Ｇａ2Ｏ3が４６．３２重量％、ＳｉＯ2が６．１８重量％）で囲まれる組成範囲内で原料を秤量する。 In consideration of the volatility of Ga, in order to manufacture the piezoelectric device substrate and the surface acoustic wave device, the second composition range shown in FIG. 1, that is, the point A (La 2 O 3 shown in FIG. 47.98 wt%, Ga 2 O 3 46.32 wt%, SiO 2 5.70 wt%),
Point B (La 2 O 3 is 48.50 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 5.18 wt%),
Point C (La 2 O 3 is 48.50 wt%, Ga 2 O 3 is 47.50 wt%, SiO 2 is 4.00 wt%),
Point D (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 47.50 wt%, SiO 2 is 5.00 wt%),
The raw materials are weighed within a composition range surrounded by point E (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 6.18 wt%).

このように、さらに組成範囲を限定した秤量によって上記と同様に引上成長を行うと共に、引き上げたランガサイト単結晶を圧電デバイス用基板に加工し、該圧電デバイス用基板に上記と同様にＳＡＷデバイスを作製する。
すなわち、Ｇａ2Ｏ3の組成比が４６．３２重量％よりも低いと、Ｇａの揮発による組成比の変化が無視できなくなり、引上成長に影響を与えるが、上記第２の組成範囲にさらに限定してＧａ2Ｏ3の組成比を高くすることにより、二次相の発生を抑制するだけでなく、Ｇａの揮発性による成長への影響がほとんど無くなり、安定した成長を行うことができる。このような圧電デバイス用基板では、より組成比のバラツキが少なくなり、この基板を用いたＳＡＷデバイスでは、さらに安定した特性を得ることができる。 In this way, pulling growth is performed in the same manner as described above by weighing with a further limited composition range, the pulled langasite single crystal is processed into a piezoelectric device substrate, and the SAW device is formed on the piezoelectric device substrate in the same manner as described above. Is made.
That is, if the composition ratio of Ga 2 O 3 is lower than 46.32% by weight, the change in the composition ratio due to the volatilization of Ga cannot be ignored and affects the pull-up growth. By limiting and increasing the composition ratio of Ga 2 O 3 , not only the generation of the secondary phase is suppressed, but also the growth of Ga due to the volatility is almost eliminated, and stable growth can be performed. Such a piezoelectric device substrate has less variation in composition ratio, and a SAW device using this substrate can obtain more stable characteristics.

本発明に係る一実施形態における圧電デバイス基板及びその製造方法において、組成を変えて育成した各ランガサイト単結晶の組成表示及び二次相の発生の有無を示す状態図である。In the piezoelectric device board | substrate in one Embodiment which concerns on this invention, and its manufacturing method, it is a state figure which shows the presence or absence of generation | occurrence | production of a secondary phase, and the composition display of each langasite single crystal grown by changing a composition. 本発明に係る一実施形態における圧電デバイス基板の製造方法において、ＣＺ法による引き上げ育成を示す概略的な断面図である。In the manufacturing method of the piezoelectric device substrate in one embodiment concerning the present invention, it is a schematic sectional view showing pulling up growth by CZ method. 本発明に係る一実施形態の表面弾性波デバイスを示す斜視図である。1 is a perspective view showing a surface acoustic wave device according to an embodiment of the present invention. 本発明に係る一実施形態における圧電デバイス基板及びその製造方法において、結晶の長さ方向における測定個所を示す単結晶の概略的な正面図である。In the piezoelectric device board | substrate in one Embodiment which concerns on this invention, and its manufacturing method, it is a schematic front view of the single crystal which shows the measurement location in the length direction of a crystal | crystallization. 本発明に係る一実施形態における圧電デバイス基板及びその製造方法において、結晶の長さ方向における測定個所に対する各原料の含有量を示すグラフである。4 is a graph showing the content of each raw material with respect to a measurement location in the crystal length direction in the piezoelectric device substrate and the manufacturing method thereof according to an embodiment of the present invention. 本発明に係る従来例における圧電デバイス基板及びその製造方法において、結晶の長さ方向における測定個所に対する各原料の含有量を示すグラフである。5 is a graph showing the content of each raw material with respect to a measurement location in the length direction of a crystal in a conventional piezoelectric device substrate and a method for manufacturing the same according to the present invention. 本発明に係る一実施形態における表面弾性波デバイスにおいて、ＳＡＷフィルタのＳＡＷ音速の基板面内バラツキを示すグラフである。5 is a graph showing in-plane variation in SAW sound speed of a SAW filter in a surface acoustic wave device according to an embodiment of the present invention.

符号の説明Explanation of symbols

１ ルツボ ７ 励振電極 ８ ＳＡＷ（表面弾性波）デバイス Ｃ ランガサイト単結晶 Ｌ 融液 Ｓ 種結晶
1 crucible 7 excitation electrode 8 SAW (surface acoustic wave) device C Langasite single crystal L melt S seed crystal

Claims (4)

ランガサイト単結晶を育成して圧電デバイス用基板に加工する圧電デバイス用基板の製造方法であって、
添付図面１に示す点Ａ（Ｌａ ２ Ｏ ３ が４７．９８重量％、Ｇａ ２ Ｏ ３ が４６．３２重量％、ＳｉＯ ２ が５．７０重量％）、
点Ｅ（Ｌａ ２ Ｏ ３ が４７．５０重量％、Ｇａ ２ Ｏ ３ が４６．３２重量％、ＳｉＯ ２ が６．１８重量％）、
点Ｆ（Ｌａ ２ Ｏ ３ が４７．５０重量％、Ｇａ ２ Ｏ ３ が４６．００重量％、ＳｉＯ ２ が６．５０重量％）で囲まれる組成範囲、又は、
点Ｅ（Ｌａ ２ Ｏ ３ が４７．５０重量％、Ｇａ ２ Ｏ ３ が４６．３２重量％、ＳｉＯ ２ が６．１８重量％）、
点Ｆ（Ｌａ ２ Ｏ ３ が４７．５０重量％、Ｇａ ２ Ｏ ３ が４６．００重量％、ＳｉＯ ２ が６．５０重量％）、
点Ｇ（Ｌａ ２ Ｏ ３ が４７．９８重量％、Ｇａ ２ Ｏ ３ が４６．００重量％、ＳｉＯ ２ が６．０２重量％）で囲まれる組成範囲から、
点Ａ１（Ｌａ２Ｏ３が４７．８１重量％、Ｇａ２Ｏ３が４６．５０重量％、ＳｉＯ２が５．６９重量％）、
点Ｂ１（Ｌａ２Ｏ３が４７．９７重量％、Ｇａ２Ｏ３が４６．２６重量％、ＳｉＯ２が５．７７重量％）、
点Ｃ１（Ｌａ２Ｏ３が４８．０４重量％、Ｇａ２Ｏ３が４６．５０重量％、ＳｉＯ２が５．４６重量％）で囲まれる組成範囲を除外した組成範囲内で秤量してルツボ内で融解させ、該ルツボ内からランガサイトの単結晶を引き上げ育成することを特徴とする圧電デバイス用基板の製造方法。 A method for manufacturing a substrate for piezoelectric devices, in which a langasite single crystal is grown and processed into a substrate for piezoelectric devices,
Point A (La 2 O 3 is 47.98 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 5.70 wt%) shown in the accompanying drawings 1 ,
Point E (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 6.18 wt%),
A composition range surrounded by point F (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 46.00 wt%, SiO 2 is 6.50 wt%), or
Point E (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 6.18 wt%),
Point F (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 46.00 wt%, SiO 2 is 6.50 wt%),
From the composition range surrounded by point G (La 2 O 3 is 47.98 wt%, Ga 2 O 3 is 46.00 wt%, SiO 2 is 6.02 wt%),
Point A1 (La 2 O 3 is 47.81 wt%, Ga 2 O 3 is 46.50 wt%, SiO 2 is 5.69 wt%),
Point B1 (La 2 O 3 is 47.97 wt%, Ga 2 O 3 is 46.26 wt%, SiO 2 is 5.77 wt%),
The crucible is weighed within the composition range excluding the composition range surrounded by the point C1 (La 2 O 3 is 48.04 wt%, Ga 2 O 3 is 46.50 wt%, SiO 2 is 5.46 wt%). A method for manufacturing a substrate for a piezoelectric device, wherein the method is melted in a crucible and pulls and grows a single crystal of langasite from the crucible. ランガサイトの単結晶で形成された圧電デバイス用基板であって、
添付図面１に示す点Ａ（Ｌａ ２ Ｏ ３ が４７．９８重量％、Ｇａ ２ Ｏ ３ が４６．３２重量％、ＳｉＯ ２ が５．７０重量％）、
点Ｅ（Ｌａ ２ Ｏ ３ が４７．５０重量％、Ｇａ ２ Ｏ ３ が４６．３２重量％、ＳｉＯ ２ が６．１８重量％）、
点Ｆ（Ｌａ ２ Ｏ ３ が４７．５０重量％、Ｇａ ２ Ｏ ３ が４６．００重量％、ＳｉＯ ２ が６．５０重量％）で囲まれる組成範囲、又は、
点Ｅ（Ｌａ ２ Ｏ ３ が４７．５０重量％、Ｇａ ２ Ｏ ３ が４６．３２重量％、ＳｉＯ ２ が６．１８重量％）、
点Ｆ（Ｌａ ２ Ｏ ３ が４７．５０重量％、Ｇａ ２ Ｏ ３ が４６．００重量％、ＳｉＯ ２ が６．５０重量％）、
点Ｇ（Ｌａ ２ Ｏ ３ が４７．９８重量％、Ｇａ ２ Ｏ ３ が４６．００重量％、ＳｉＯ ２ が６．０２重量％）で囲まれる組成範囲から、
点Ａ１（Ｌａ２Ｏ３が４７．８１重量％、Ｇａ２Ｏ３が４６．５０重量％、ＳｉＯ２が５．６９重量％）、
点Ｂ１（Ｌａ２Ｏ３が４７．９７重量％、Ｇａ２Ｏ３が４６．２６重量％、ＳｉＯ２が５．７７重量％）、
点Ｃ１（Ｌａ２Ｏ３が４８．０４重量％、Ｇａ２Ｏ３が４６．５０重量％、ＳｉＯ２が５．４６重量％）で囲まれる組成範囲を除外した組成範囲内で秤量してルツボ内で融解させ、該ルツボ内から引き上げ育成された単結晶であることを特徴とする圧電デバイス用基板。 A piezoelectric device substrate formed of a single crystal of langasite ,
Point A (La 2 O 3 is 47.98 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 5.70 wt%) shown in the accompanying drawings 1 ,
Point E (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 6.18 wt%),
A composition range surrounded by point F (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 46.00 wt%, SiO 2 is 6.50 wt%), or
Point E (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 6.18 wt%),
Point F (La 2 O 3 is 47.50 wt%, Ga 2 O 3 is 46.00 wt%, SiO 2 is 6.50 wt%),
From the composition range surrounded by point G (La 2 O 3 is 47.98 wt%, Ga 2 O 3 is 46.00 wt%, SiO 2 is 6.02 wt%),
Point A1 (La 2 O 3 is 47.81 wt%, Ga 2 O 3 is 46.50 wt%, SiO 2 is 5.69 wt%),
Point B1 (La 2 O 3 is 47.97 wt%, Ga 2 O 3 is 46.26 wt%, SiO 2 is 5.77 wt%),
The crucible is weighed within the composition range excluding the composition range surrounded by the point C1 (La 2 O 3 is 48.04 wt%, Ga 2 O 3 is 46.50 wt%, SiO 2 is 5.46 wt%). A piezoelectric device substrate, characterized in that it is a single crystal that is melted inside and grown from the inside of the crucible. 引き上げにより育成されたランガサイトの単結晶で形成された圧電デバイス用基板であって、
前記ランガサイトは、
添付図面１に示す点ａ（Ｌａ ２ Ｏ ３ が４７．９８重量％、Ｇａ ２ Ｏ ３ が４６．３２重量％、ＳｉＯ ２ が５．７０重量％）、
点ｅ（Ｌａ ２ Ｏ ３ が４７．５２重量％、Ｇａ ２ Ｏ ３ が４６．３２重量％、ＳｉＯ ２ が６．１６重量％）、
点ｆ（Ｌａ ２ Ｏ ３ が４７．５１重量％、Ｇａ ２ Ｏ ３ が４６．０１重量％、ＳｉＯ ２ が６．４８重量％）で囲まれる組成範囲、又は、
点ｅ（Ｌａ ２ Ｏ ３ が４７．５２重量％、Ｇａ ２ Ｏ ３ が４６．３２重量％、ＳｉＯ ２ が６．１６重量％）、
点ｆ（Ｌａ ２ Ｏ ３ が４７．５１重量％、Ｇａ ２ Ｏ ３ が４６．０１重量％、ＳｉＯ ２ が６．４８重量％）、
点ｇ（Ｌａ ２ Ｏ ３ が４７．９８重量％、Ｇａ ２ Ｏ ３ が４６．０２重量％、ＳｉＯ ２ が６．００重量％）で囲まれる組成範囲から、
点ａ１（Ｌａ２Ｏ３が４７．８２重量％、Ｇａ２Ｏ３が４６．５０重量％、ＳｉＯ２が５．６８重量％）、
点ｂ１（Ｌａ２Ｏ３が４７．９７重量％、Ｇａ２Ｏ３が４６．２７重量％、ＳｉＯ２が５．７６重量％）、
点ｃ１（Ｌａ２Ｏ３が４８．０３重量％、Ｇａ２Ｏ３が４６．４９重量％、ＳｉＯ２が５．４８重量％）で囲まれる組成範囲を除外した組成範囲内の単結晶であることを特徴とする圧電デバイス用基板。 A piezoelectric device substrate formed of a single crystal of langasite grown by pulling,
The Langasite is
Point a (La 2 O 3 is 47.98 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 5.70 wt%) shown in the accompanying drawings 1 ,
Point e (La 2 O 3 is 47.52 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 6.16 wt%),
A composition range surrounded by a point f (La 2 O 3 is 47.51 wt%, Ga 2 O 3 is 46.01 wt%, SiO 2 is 6.48 wt%), or
Point e (La 2 O 3 is 47.52 wt%, Ga 2 O 3 is 46.32 wt%, SiO 2 is 6.16 wt%),
Point f (La 2 O 3 is 47.51 wt%, Ga 2 O 3 is 46.01 wt%, SiO 2 is 6.48 wt%),
From the composition range surrounded by the point g (La 2 O 3 is 47.98 wt%, Ga 2 O 3 is 46.02 wt%, SiO 2 is 6.00 wt%),
Point a1 (La 2 O 3 is 47.82 wt%, Ga 2 O 3 is 46.50 wt%, SiO 2 is 5.68 wt%),
Point b1 (La 2 O 3 is 47.97 wt%, Ga 2 O 3 is 46.27 wt%, SiO 2 is 5.76 wt%),
It is a single crystal within the composition range excluding the composition range surrounded by the point c1 (La 2 O 3 is 48.03 wt%, Ga 2 O 3 is 46.49 wt%, SiO 2 is 5.48 wt%). A piezoelectric device substrate characterized by the above-mentioned. 請求項２又は３に記載の圧電デバイス基板の表面上に表面弾性波を送受信する電極を形成したことを特徴とする表面弾性波デバイス。   A surface acoustic wave device, wherein an electrode for transmitting and receiving surface acoustic waves is formed on the surface of the piezoelectric device substrate according to claim 2.
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