JP3233489B2 - Surface acoustic wave device and method of manufacturing the same - Google Patents
Surface acoustic wave device and method of manufacturing the sameInfo
- Publication number
- JP3233489B2 JP3233489B2 JP08570793A JP8570793A JP3233489B2 JP 3233489 B2 JP3233489 B2 JP 3233489B2 JP 08570793 A JP08570793 A JP 08570793A JP 8570793 A JP8570793 A JP 8570793A JP 3233489 B2 JP3233489 B2 JP 3233489B2
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- Prior art keywords
- acoustic wave
- surface acoustic
- film
- wave device
- plasma
- Prior art date
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Description
【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION
【０００１】[0001]
【産業上の利用分野】本発明は、弾性表面波素子とその
製造方法とに関する。The present invention relates to a surface acoustic wave device and a method for manufacturing the same.
【０００２】[0002]
【従来の技術】ダイヤモンド薄膜は、弾性表面波（ＳＡ
Ｗ）素子の表面波伝搬膜として注目を浴びている。弾性
表面波素子は、表面波伝搬膜と圧電膜とが積層された構
成となっており、圧電膜にクシ型電極により電界を印加
して振動させることにより、表面波伝搬膜に表面波を励
振するものである。弾性表面波素子は、フィルタを始め
として通信分野で広く利用されているが、簡単な構造で
良好な特性が得られることから、移動通信等の分野への
適用が期待されている。移動通信では、通常、ＵＨＦ帯
を用いるため、動作周波数が極めて高くなる。弾性表面
波素子の動作周波数を高くするためには、例えば、クシ
型電極の周期を小さくしたり、音速の速い表面波伝搬膜
を用いたりする。クシ型電極は、通常、フォトリソグラ
フィーにより形成されるため、電極周期を小さくするに
は限界がある。一方、ダイヤモンド中での音速は極めて
速いため、表面波伝搬膜としてダイヤモンド薄膜を用い
ればギガヘルツ（ＧＨｚ）帯に対応できる弾性表面波素
子が実現する可能性がでてくる。2. Description of the Related Art A diamond thin film has a surface acoustic wave (SA).
W) Attention has been paid to the surface wave propagation film of the element. The surface acoustic wave element has a configuration in which a surface wave propagation film and a piezoelectric film are laminated, and a surface wave is excited in the surface wave propagation film by applying an electric field to the piezoelectric film with a comb-shaped electrode and vibrating. Is what you do. Surface acoustic wave devices are widely used in the field of communications, including filters, but are expected to be applied to the field of mobile communications and the like because good characteristics can be obtained with a simple structure. In mobile communication, since the UHF band is usually used, the operating frequency becomes extremely high. In order to increase the operating frequency of the surface acoustic wave element, for example, the period of the comb-shaped electrode is reduced, or a surface acoustic wave propagation film having a high sound speed is used. Since the comb-type electrode is usually formed by photolithography, there is a limit in reducing the electrode period. On the other hand, since the sound speed in diamond is extremely high, if a diamond thin film is used as the surface wave propagation film, there is a possibility that a surface acoustic wave device that can cope with the gigahertz (GHz) band will be realized.
【０００３】ダイヤモンド薄膜の形成には、バルクダイ
ヤモンドに近い結晶構造が得られることからＣＶＤ法が
好ましく用いられている。しかし、表面波伝搬膜に必要
な厚さは約１０μm 以上であり、このような厚さのダイ
ヤモンド膜を通常のＣＶＤ法で形成した場合には結晶粒
径が１μm 程度の多結晶膜となってしまう。ダイヤモン
ドは音速に異方性があるので、このような多結晶膜を用
いると膜を伝搬する音波の位相にばらつきが生じ、良好
な特性が得られない。また、結晶粒径が弾性表面波の波
長と同程度以上となると、結晶粒界による散乱のために
伝搬損失が大きくなるという問題がある。また、このよ
うな多結晶ダイヤモンド薄膜は、弾性表面波の波長と比
較して表面の凹凸が激しいので、表面波が散乱して伝搬
ロスを生じる。伝搬される際に表面波が侵入する深さは
極めて浅く、ほぼその波長程度の深さとなるので、使用
波長が短くなるほど膜表面の凹凸による伝搬ロスの割合
は大きくなる。これを防ぐために膜形成後に表面を研磨
しなければならず、低コスト化が困難である。In forming a diamond thin film, a CVD method is preferably used because a crystal structure close to that of bulk diamond can be obtained. However, the thickness required for the surface wave propagation film is about 10 μm or more, and when a diamond film having such a thickness is formed by a normal CVD method, a polycrystalline film having a crystal grain size of about 1 μm is obtained. I will. Since diamond has anisotropy in sound velocity, the use of such a polycrystalline film causes a variation in the phase of a sound wave propagating through the film, so that good characteristics cannot be obtained. Further, when the crystal grain size is equal to or larger than the wavelength of the surface acoustic wave, there is a problem that propagation loss increases due to scattering by crystal grain boundaries. In addition, since such a polycrystalline diamond thin film has severe surface irregularities as compared with the wavelength of the surface acoustic wave, the surface wave is scattered and a propagation loss occurs. The depth at which the surface wave penetrates when it is propagated is extremely shallow, which is approximately the same wavelength. Therefore, the shorter the wavelength used, the greater the proportion of propagation loss due to the unevenness of the film surface. In order to prevent this, the surface must be polished after the film is formed, and it is difficult to reduce the cost.
【０００４】一方、結晶粒をもたない非晶質炭素膜（通
常、ダイヤモンド状炭素膜と呼ばれる）を表面波伝搬膜
として使うこともある。非晶質炭素膜は、音速に異方性
はないがダイヤモンド膜よりも音速が遅い。したがっ
て、電極周期をより小さくしなければならず、高周波へ
の対応が難しい。On the other hand, an amorphous carbon film having no crystal grains (usually called a diamond-like carbon film) is sometimes used as a surface wave propagation film. The amorphous carbon film has no sound velocity anisotropy, but has a lower sound speed than the diamond film. Therefore, the electrode period must be made smaller, and it is difficult to cope with high frequencies.
【０００５】[0005]
【発明が解決しようとする課題】本発明は、弾性表面波
の伝搬速度が高速でその伝搬効率が高く、特性の良好な
弾性表面波素子を提供することを目的とする。SUMMARY OF THE INVENTION It is an object of the present invention to provide a surface acoustic wave device having a high propagation speed of a surface acoustic wave, high propagation efficiency, and excellent characteristics.
【０００６】[0006]
【課題を解決するための手段】これらの目的は、下記
（１）〜（８）の本発明によって達成される。 （１）基板上に表面波伝搬膜および圧電膜をこの順で有
し、圧電膜に電界を印加する電極を有する弾性表面波素
子であって、前記表面波伝搬膜が、平均結晶粒径１００
nm以下のダイヤモンドを含む炭素膜であることを特徴と
する弾性表面波素子。 （２）前記ダイヤモンドの平均結晶粒径が５nm以上であ
る上記（１）の弾性表面波素子。 （３）前記表面波伝搬膜中の音速が５７００m/s 以上で
ある上記（１）または（２）の弾性表面波素子。 （４）上記（１）ないし（３）のいずれかの弾性表面波
素子を製造する方法であって、１×１０-5〜５×１０-3
Torrの圧力中でプラズマＣＶＤ法により前記表面波伝搬
膜を形成することを特徴とする弾性表面波素子の製造方
法。 （５）原料中性粒子ガスを加熱体に衝突させてガスの粒
子速度を増加させた後、前記ガスの分子を電離、解離し
てプラズマＣＶＤを行なう上記（４）の弾性表面波素子
の製造方法。 （６）前記加熱体が加熱管であり、この加熱管内壁に前
記ガスを衝突させる上記（５）の弾性表面波素子の製造
方法。 （７）前記加熱体が７００Ｋ以上の温度に加熱されてい
る上記（５）または（６）の弾性表面波素子の製造方
法。 （８）前記分子の電離・解離を有磁場マイクロ波プラズ
マによって行なう上記（５）ないし（７）のいずれかの
弾性表面波素子の製造方法。These objects are achieved by the present invention described in the following (1) to (8). (1) A surface acoustic wave device having a surface wave propagation film and a piezoelectric film on a substrate in this order, and having an electrode for applying an electric field to the piezoelectric film, wherein the surface wave propagation film has an average crystal grain size of 100
A surface acoustic wave device comprising a carbon film containing diamond of nm or less. (2) The surface acoustic wave device according to (1), wherein the diamond has an average crystal grain size of 5 nm or more. (3) The surface acoustic wave device according to the above (1) or (2), wherein the sound velocity in the surface wave propagation film is 5700 m / s or more. (4) A method of manufacturing a surface acoustic wave device according to any one of the above (1) to (3), wherein the method is 1 × 10 −5 to 5 × 10 −3.
A method for manufacturing a surface acoustic wave device, comprising forming the surface wave propagation film by a plasma CVD method at a pressure of Torr. (5) Manufacturing the surface acoustic wave device according to (4) above, wherein the raw material neutral particle gas is caused to collide with the heating element to increase the particle velocity of the gas, and then the gas molecules are ionized and dissociated to perform plasma CVD. Method. (6) The method for manufacturing a surface acoustic wave device according to (5), wherein the heating body is a heating tube, and the gas collides against an inner wall of the heating tube. (7) The method for manufacturing a surface acoustic wave device according to the above (5) or (6), wherein the heating body is heated to a temperature of 700 K or more. (8) The method for manufacturing a surface acoustic wave device according to any one of the above (5) to (7), wherein the molecules are ionized and dissociated by magnetic field microwave plasma.
【０００７】[0007]
【作用および効果】本発明の弾性表面波素子は、平均結
晶粒径１００nm以下のダイヤモンドを含む炭素膜を表面
波伝搬膜として用いる。このように結晶粒径が小さい膜
は、短波長の弾性表面波に対しても等方的な媒質として
振る舞うので、弾性表面波の位相の乱れは殆ど生じず、
良好な素子特性が得られる。また、結晶粒径が極めて小
さいために結晶粒界による弾性表面波の散乱が殆ど生じ
ないので、伝搬損失が極めて小さくなる。したがって、
本発明では極めて短波長の弾性表面波を使用することが
でき、しかも、前記表面波伝搬膜は非晶質炭素膜に比べ
音速が速いので、ギガヘルツ帯に対応する弾性表面波素
子が容易に実現する。Function and Effect The surface acoustic wave device of the present invention uses a carbon film containing diamond having an average crystal grain size of 100 nm or less as a surface wave propagation film. Such a film having a small crystal grain size behaves as an isotropic medium even for a short-wavelength surface acoustic wave, so that the phase of the surface acoustic wave hardly disturbs,
Good device characteristics are obtained. Further, since the crystal grain size is extremely small, the scattering of the surface acoustic wave by the crystal grain boundary hardly occurs, so that the propagation loss becomes extremely small. Therefore,
In the present invention, a surface acoustic wave having an extremely short wavelength can be used, and the surface acoustic wave propagation film has a higher sound velocity than an amorphous carbon film, so that a surface acoustic wave element corresponding to a gigahertz band can be easily realized. I do.
【０００８】また、本発明では表面伝搬膜表面の凹凸が
極めて小さくなるので、素子化する際に膜表面の研磨が
不要である。Further, in the present invention, since the unevenness on the surface of the surface propagation film becomes extremely small, it is not necessary to polish the film surface when the device is formed.
【０００９】[0009]
【具体的構成】以下、本発明の具体的構成について詳細
に説明する。[Specific Configuration] Hereinafter, a specific configuration of the present invention will be described in detail.
【００１０】本発明の弾性表面波素子の構成例を、図１
に示す。同図において、弾性表面波素子１１は、基板１
２上に、表面波伝搬膜１４および圧電膜１５をこの順で
有し、圧電膜に電界を印加するためのクシ型の電極１６
が表面波伝搬膜１４上に設けられている。FIG. 1 shows a configuration example of a surface acoustic wave device according to the present invention.
Shown in In the figure, the surface acoustic wave element 11 is
2, a surface-wave propagation film 14 and a piezoelectric film 15 in this order, and a comb-shaped electrode 16 for applying an electric field to the piezoelectric film.
Are provided on the surface acoustic wave propagation film 14.
【００１１】表面波伝搬膜は、平均結晶粒径１００nm以
下のダイヤモンドを含む炭素膜である。前記ダイヤモン
ドの平均結晶粒径が前記範囲を超えると上記した本発明
の効果が得られなくなる。前記ダイヤモンドの平均結晶
粒径の下限は特にないが、平均結晶粒径が５nm未満とな
ると音速が低下する傾向が顕著になる。なお、ダイヤモ
ンドのより好ましい平均結晶粒径は２０〜１００nmであ
る。膜中に多結晶ダイヤモンドが含まれていることはＸ
線回折により確認することができ、ダイヤモンドの平均
結晶粒径は透過型電子顕微鏡などにより測定することが
できる。また、表面波伝搬膜表面が平坦で自形面が現わ
れていないことは、走査型電子顕微鏡等により確認する
ことができる。The surface wave propagation film is a carbon film containing diamond having an average crystal grain size of 100 nm or less. If the average crystal grain size of the diamond exceeds the above range, the effects of the present invention described above cannot be obtained. There is no particular lower limit on the average crystal grain size of the diamond, but when the average crystal grain size is less than 5 nm, the tendency for the sound speed to decrease becomes significant. The more preferred average crystal grain size of diamond is 20 to 100 nm. The fact that the film contains polycrystalline diamond is X
The average crystal grain size of diamond can be measured by a transmission electron microscope or the like. In addition, it can be confirmed by a scanning electron microscope or the like that the surface of the surface acoustic wave propagation film is flat and no self-shaped surface appears.
【００１２】表面波伝搬膜の好ましい厚さは、動作周波
数帯域等の各種条件によっても異なるが、通常、１０〜
２０μm 程度である。The preferred thickness of the surface acoustic wave propagation film varies depending on various conditions such as the operating frequency band, but is usually in the range of 10 to 10.
It is about 20 μm.
【００１３】表面伝搬膜中の音速は圧電膜の構成によっ
ても異なるが、通常、５７００m/s以上、特に８０００m
/s 以上と高速である。Although the speed of sound in the surface propagation film varies depending on the configuration of the piezoelectric film, it is usually 5700 m / s or more, and especially 8000 m
Faster than / s.
【００１４】表面波伝搬膜は、ＣＶＤ法により形成され
ることが好ましい。ＣＶＤ法としては、各種プラズマＣ
ＶＤ法または各種熱ＣＶＤ法から選択することが好まし
く、特にプラズマＣＶＤ法を用いることが好ましい。The surface wave propagation film is preferably formed by a CVD method. As the CVD method, various types of plasma C
It is preferable to select from the VD method or various thermal CVD methods, and it is particularly preferable to use a plasma CVD method.
【００１５】本発明では、好ましくは１×１０-5〜５×
１０-3Torr、より好ましくは１×１０-4〜５×１０-3To
rrの圧力中でプラズマＣＶＤ法により表面波伝搬膜を形
成する。膜形成時の雰囲気圧力が前記範囲を超えている
と、結晶粒径の小さい膜が得られにくい。また、雰囲気
圧力が前記範囲未満であると、膜形成が難しくなる。In the present invention, preferably 1 × 10 −5 to 5 ×
10 −3 Torr, more preferably 1 × 10 −4 to 5 × 10 −3 To
A surface wave propagation film is formed by a plasma CVD method at a pressure of rr. If the atmospheric pressure during film formation exceeds the above range, it is difficult to obtain a film having a small crystal grain size. If the atmospheric pressure is less than the above range, it is difficult to form a film.
【００１６】プラズマＣＶＤ法におけるプラズマ発生源
としては、例えば特開昭６４−６５８４３号公報に開示
されているようなエレクトロン・サイクロトロン・レゾ
ナンス（ＥＣＲ）を利用したプラズマ生成手段や高周波
誘導加熱を利用したプラズマ生成手段等が挙げられる。
これらのうち、高密度の電子が得られて処理速度が高い
ことから、ＥＣＲを用いるものが好ましい。As a plasma source in the plasma CVD method, for example, a plasma generating means using an electron cyclotron resonance (ECR) or a high frequency induction heating as disclosed in Japanese Patent Application Laid-Open No. 64-65843 is used. Plasma generation means and the like can be mentioned.
Among them, those using ECR are preferable because high density electrons can be obtained and the processing speed is high.
【００１７】ＥＣＲ型プラズマＣＶＤ装置では、電界と
磁界との相互作用により共鳴的に電子を加速し、この電
子の衝突によりガスをプラズマ化して、プラズマ中のイ
オン、ラジカル等を基板上に堆積させることにより成膜
を行なう。また、このプラズマから電子を引き出し、引
き出された電子を原料ガスに衝突させてプラズマ化し、
発生したイオン、ラジカル等を基板上に堆積させること
もできる。In an ECR plasma CVD apparatus, electrons are resonantly accelerated by the interaction between an electric field and a magnetic field, and the collision of the electrons turns the gas into plasma, thereby depositing ions and radicals in the plasma on the substrate. Thus, a film is formed. In addition, electrons are extracted from this plasma, and the extracted electrons collide with a source gas to be turned into plasma,
The generated ions and radicals can be deposited on the substrate.
【００１８】本発明における表面波伝搬膜の形成に好適
なプラズマＣＶＤ装置を、図２および図３に示す。FIGS. 2 and 3 show a plasma CVD apparatus suitable for forming a surface acoustic wave propagation film according to the present invention.
【００１９】図２および図３に示されるプラズマ処理装
置１は、真空系８内にプラズマ生成室７を有し、このプ
ラズマ生成室７に連通して原料ガス導入管２が設けられ
ている。プラズマ生成室７には、マイクロ波電源（図示
せず）と接続された導波管９がマイクロ波導入窓を介し
て設けられており、また、プラズマ生成室７の外周には
磁石としてヘルムホルツ型の電磁石４が設けられてお
り、これらがＥＣＲ型等の有磁場マイクロ波プラズマ生
成手段を構成している。また、真空系８内には真空排気
口が設けられ、所定の動作圧力とすることができるとと
もに、基板ホルダ６が移動可能に設けられており、基板
を所定の温度に加熱した状態で、プラズマ生成室７内の
所定の位置に載置できるようにされている。The plasma processing apparatus 1 shown in FIGS. 2 and 3 has a plasma generation chamber 7 in a vacuum system 8, and a source gas introduction pipe 2 is provided in communication with the plasma generation chamber 7. A waveguide 9 connected to a microwave power supply (not shown) is provided in the plasma generation chamber 7 through a microwave introduction window, and a Helmholtz type magnet is provided around the plasma generation chamber 7 as a magnet. Are provided, and these constitute a magnetic field microwave plasma generating means such as an ECR type. Further, a vacuum exhaust port is provided in the vacuum system 8 so that a predetermined operating pressure can be set, and the substrate holder 6 is provided so as to be movable. It can be placed at a predetermined position in the generation chamber 7.
【００２０】原料ガス導入管２の先端開口には、加熱体
として加熱管３が接続されており、導入された原料中性
粒子ガスが加熱管３の内壁に衝突するように構成されて
いる。加熱管３の内壁は７００Ｋ以上、特に１６００〜
２０００Ｋの温度とされており、ガス粒子はこの内壁に
実質的に弾性衝突して、粒子速度（運動エネルギー）が
増大する。加速手段としての加熱管の構造やガスの衝突
のさせ方等について特に制限はなく、Ｔａ、Ｍｏ、Ｗ等
の管に発熱体をらせん状に巻いたり、ハニカム型ヒータ
を用いたりする等が可能であるが、加速効率を高めるた
めには図４に示されるような加熱管３を用いることが好
ましい。図示例では、例えばＷ、Ｔａ等の内径０．７〜
１．４mm、肉厚０．１〜０．２mm、長さ１５〜４０mmの
管体３１の両端に、一対の電極３５を接続し、印加電圧
を変化させながら直接通電加熱を行ない、所定の温度と
する構造とされている。この他、加熱手段としては、抵
抗加熱、誘導加熱等いずれであってもよく、管体３１の
材質についても特に制限はない。A heating pipe 3 as a heating element is connected to the leading end opening of the raw material gas introduction pipe 2 so that the introduced raw material neutral particle gas collides with the inner wall of the heating pipe 3. The inner wall of the heating tube 3 is 700K or more, especially 1600 to
The temperature is set to 2000 K, and the gas particles substantially collide with the inner wall, and the particle velocity (kinetic energy) increases. There is no particular limitation on the structure of the heating tube as an accelerating means and the method of causing gas collision, and it is possible to spirally wind a heating element around a tube of Ta, Mo, W, etc., use a honeycomb type heater, and the like. However, in order to increase the acceleration efficiency, it is preferable to use a heating tube 3 as shown in FIG. In the illustrated example, for example, the inner diameter of W, Ta, or the like is 0.7 to 0.7.
A pair of electrodes 35 are connected to both ends of a tube 31 having a thickness of 1.4 mm, a wall thickness of 0.1 to 0.2 mm, and a length of 15 to 40 mm, and are directly heated by heating while changing an applied voltage. The structure is as follows. In addition, the heating means may be any of resistance heating, induction heating, and the like, and the material of the tube 31 is not particularly limited.
【００２１】原料ガス導入管２からこの加熱管３を介し
てプラズマ生成室７内に原料中性粒子ガスを導入し、粒
子速度を増大させる。このとき、原料中性粒子ガスは、
通常、約０．０２５eVの運動エネルギーと約６３０m/se
c の粒子速度をもって導入されるが、加熱管により原料
中性粒子ガスは０．０６eV以上、特に０．１１〜０．２
１eVの運動エネルギーと１３００〜１７８０m/sec （１
３００〜２４００Ｋ）の粒子速度を与えられる。A raw material neutral gas is introduced into the plasma generation chamber 7 from the raw gas introduction pipe 2 through the heating pipe 3 to increase the particle velocity. At this time, the raw material neutral particle gas is
Normally, kinetic energy of about 0.025 eV and about 630 m / se
c is introduced at a particle velocity of c, and the raw material neutral particle gas is supplied at a rate of 0.06 eV or more, particularly 0.11 to 0.2
Kinetic energy of 1 eV and 1300-1780 m / sec (1
300 to 2400 K).
【００２２】プラズマ生成室７では、マイクロ波導入窓
からマイクロ波が導入されており、同時に、プラズマ生
成室内部には電磁石４により、好ましくはＥＣＲ条件を
満たす磁界が付与されている。このため、プラズマ生成
室７内の電子は、この磁界とマイクロ波の電界とにより
加速されて加速ガス粒子に衝突し、プラズマが生成す
る。そして、前述したような低い動作圧力でのプラズマ
ＣＶＤが可能となり、３インチ平方以上、特に４〜６イ
ンチ平方の大面積での処理が可能である。また基板温度
も通常より低温化することが可能となる。In the plasma generation chamber 7, microwaves are introduced from a microwave introduction window, and at the same time, a magnetic field which preferably satisfies ECR conditions is applied to the inside of the plasma generation chamber by the electromagnet 4. Therefore, the electrons in the plasma generation chamber 7 are accelerated by the magnetic field and the electric field of the microwave, collide with the accelerating gas particles, and generate plasma. Then, plasma CVD can be performed at a low operating pressure as described above, and processing can be performed in a large area of 3 inches square or more, particularly 4 to 6 inches square. In addition, the substrate temperature can be lower than usual.
【００２３】加熱管３等の加熱体は、基板５の好ましく
は垂直上方に設けることが好ましく、加速粒子は基板面
にほぼ垂直に差し向けられ、その間プラズマ中にて電離
・解離を行なうことが好ましい。これにより処理効率が
向上する。The heating element such as the heating tube 3 is preferably provided vertically above the substrate 5, and the accelerating particles are directed substantially perpendicular to the substrate surface, during which ionization and dissociation may be performed in the plasma. preferable. This improves processing efficiency.
【００２４】なお、以上では、プラズマ生成室７内で処
理を行なう例について述べてきたが、ＥＣＲキャビティ
等のプラズマ生成室と連通する系内でプラズマ処理を行
なったり、イオン引き出し電極等を用いたりして、生成
室７外でプラズマ処理を行なうことも可能である。In the above, an example in which the processing is performed in the plasma generation chamber 7 has been described. However, the plasma processing is performed in a system that communicates with the plasma generation chamber such as an ECR cavity, or an ion extraction electrode or the like is used. Then, it is also possible to perform the plasma processing outside the generation chamber 7.
【００２５】なお、本発明では、このようなプラズマＣ
ＶＤ装置の他、特願平４−３５５７８４号に開示されて
いるプラズマＣＶＤ装置、すなわち、ＥＣＲ型のプラズ
マ生成手段と被処理体ホルダとが設けられたプラズマ室
を有し、プラズマ生成手段により形成されたプラズマ高
密度領域と被処理体ホルダとの間に遮蔽部材が設けられ
た構成のプラズマＣＶＤ装置、あるいは、プラズマ生成
室と処理室とが設けられたプラズマ室を有し、プラズマ
生成室にプラズマ生成手段が設けられ、処理室に被処理
体ホルダが設けられ、プラズマ生成室で生成したプラズ
マから電子を処理室に引き出すための電子引き出し電極
がプラズマ生成室と処理室との間に設けられ、電子引き
出し電極と被処理体ホルダとの間に遮蔽部材が設けられ
た構成のプラズマＣＶＤ装置も好ましく用いることがで
きる。In the present invention, such a plasma C
In addition to a VD apparatus, a plasma CVD apparatus disclosed in Japanese Patent Application No. 4-355784, that is, a plasma chamber provided with an ECR type plasma generation means and a workpiece holder, and formed by the plasma generation means A plasma CVD apparatus having a configuration in which a shielding member is provided between the processed plasma high-density region and the workpiece holder, or a plasma chamber in which a plasma generation chamber and a processing chamber are provided. A plasma generation means is provided, a workpiece holder is provided in the processing chamber, and an electron extraction electrode for extracting electrons from the plasma generated in the plasma generation chamber to the processing chamber is provided between the plasma generation chamber and the processing chamber. In addition, a plasma CVD apparatus having a structure in which a shielding member is provided between an electron extraction electrode and a workpiece holder can also be preferably used.
【００２６】ＣＶＤ法における原料ガスとしてはＣＨ4
やＣ2 Ｈ4 等の各種炭素化合物などを用いればよい。ま
た、これらに加えてＣＯ2 を用いれば、膜の結晶性が向
上する。キャリアガスとしてＨ2 ガスを用いることが好
ましい。Ｈ2 ガスは膜中の不純物を排除する作用を有す
る。原料ガス流量とキャリアガス流量との合計に対し、
キャリアガス流量は８０％以上、特に８５〜９９％とす
ることが好ましい。キャリアガス流量をこのような範囲
とすることにより、極めて純度の高い膜を形成すること
ができる。CH 4 is used as a source gas in the CVD method.
And various carbon compounds such as C 2 H 4 . When CO 2 is used in addition to these, the crystallinity of the film is improved. It is preferable to use H 2 gas as a carrier gas. H 2 gas has a function of removing impurities in the film. For the sum of the source gas flow rate and the carrier gas flow rate,
The carrier gas flow rate is preferably 80% or more, particularly preferably 85 to 99%. By setting the flow rate of the carrier gas in such a range, a film with extremely high purity can be formed.
【００２７】膜形成の際の基板温度は、４００〜７００
℃とすることが好ましい。The substrate temperature during film formation is 400 to 700
It is preferably set to ° C.
【００２８】基板１２の材質に特に制限はなく、各種金
属、合金およびセラミックスから適宜選択すればよく、
例えば、Ｓｉ、Ｗ、Ｍｏ、Ｃｕ、Ｔａ、ＡｌおよびＴｉ
から選択される１種以上の元素を含有する金属または合
金、あるいはＡｌ2 Ｏ3 、ＺｒＯ2 、ＭｇＯ等のセラミ
ックス等を好ましく用いることができる。また、基板の
寸法も特に限定されない。The material of the substrate 12 is not particularly limited, and may be appropriately selected from various metals, alloys, and ceramics.
For example, Si, W, Mo, Cu, Ta, Al and Ti
Metals or alloys containing at least one element selected from the group consisting of, or ceramics such as Al 2 O 3 , ZrO 2 , and MgO can be preferably used. Further, the dimensions of the substrate are not particularly limited.
【００２９】圧電膜１５の材質は、ＬｉＮｂＯ3 やＺｎ
Ｏ、ＡｌＮ等の各種圧電体から選択すればよく、通常、
スパッタ法等により成膜される。圧電膜の厚さは、通
常、０．１〜４μm 程度とする。一般に、圧電膜が厚い
ほど弾性表面波への変換効率は高くなるが、音速は遅く
なる。The material of the piezoelectric film 15 is LiNbO 3 or Zn.
What is necessary is just to select from various piezoelectric bodies, such as O and AlN.
The film is formed by a sputtering method or the like. The thickness of the piezoelectric film is usually about 0.1 to 4 μm. Generally, the thicker the piezoelectric film, the higher the conversion efficiency to surface acoustic waves, but the lower the speed of sound.
【００３０】電極１６は、通常、真空蒸着法等により形
成され、各種のエッチングによりクシ型形状とされる。
電極周期は、動作周波数、表面波伝搬膜の音速、圧電膜
の音速およびその厚さなどに応じて適宜設定すればよ
い。図１に示される構成例では、クシ型の電極１６は表
面波伝搬膜１４上に形成され、その上から圧電膜１５が
形成されているが、本発明ではこの態様に限らず、例え
ば、圧電膜上に電極を形成するなど、弾性表面波素子と
して利用できる電極構成であればどのようなものであっ
てもよい。The electrode 16 is usually formed by a vacuum evaporation method or the like, and is formed into a comb shape by various kinds of etching.
The electrode cycle may be appropriately set according to the operating frequency, the sound speed of the surface wave propagation film, the sound speed of the piezoelectric film, its thickness, and the like. In the configuration example shown in FIG. 1, the comb-shaped electrode 16 is formed on the surface wave propagation film 14, and the piezoelectric film 15 is formed thereon. However, the present invention is not limited to this mode. Any electrode configuration may be used as long as it can be used as a surface acoustic wave element, such as forming an electrode on a film.
【００３１】基板１２と表面波伝搬膜１４との間には、
必要に応じて下地膜を設けてもよい。下地膜は、通常、
表面波伝搬膜の接着性を向上させるために設けられる
が、その場合、基板構成元素と炭素とを含む組成、例え
ばＳｉＣやＷＣ等とすることが好ましい。Between the substrate 12 and the surface wave propagation film 14,
A base film may be provided as necessary. The base film is usually
It is provided to improve the adhesiveness of the surface wave propagation film. In this case, it is preferable to use a composition containing a substrate constituent element and carbon, for example, SiC or WC.
【００３２】[0032]
【実施例】以下、具体的実施例を挙げ、本発明をさらに
詳細に説明する。EXAMPLES Hereinafter, the present invention will be described in more detail with reference to specific examples.
【００３３】図２に示される構成を有するプラズマＣＶ
Ｄ装置の基板ホルダ上にＳｉ（１００）基板を載置し、
系内を１×１０-5Torrに排気して、基板温度を６００℃
に上昇させ、さらに排気を行なった。A plasma CV having the structure shown in FIG.
Place the Si (100) substrate on the substrate holder of the D device,
The system is evacuated to 1 × 10 -5 Torr and the substrate temperature is set to 600 ° C.
, And further evacuated.
【００３４】次いで、中性粒子の加速源である加熱管３
を通電加熱した。放射温度計で温度をモニタしたとこ
ろ、２０００Ｋであった。加熱管３のサイズは内径０．
７mm、肉厚０．１mm、長さ４０mmとした。ＣＨ4 の平均
速度Vave＝（８kT／πmCH4）1/ 2 は１６２５m/sec と推
定される。Next, a heating tube 3 serving as an acceleration source of neutral particles
Was electrically heated. When the temperature was monitored with a radiation thermometer, it was 2000K. The size of the heating tube 3 is 0.
The thickness was 7 mm, the wall thickness was 0.1 mm, and the length was 40 mm. Average speed Vave = (8kT / πmCH 4) 1/2 of CH 4 is estimated to be 1625m / sec.
【００３５】この後、原料ガスを導入した。原料ガスは
流量比でＣＨ4 ：ＣＯ2 ：Ｈ2 ＝５：１０：８５とし
た。次いでマイクロ波および電磁石の電源を入れ、プラ
ズマを生成させた。プラズマはキャビティのプラズマ生
成室７内に一様に広がっていることが確認された。さら
に、２．４５GHz 、５００W のマイクロ波を投入し、印
加磁界８７５Ｇ、基板温度６００℃、１×１０-3Torrの
動作圧力で厚さ１５μmの表面波伝搬膜を形成した。こ
の際、加熱管３は基板５の垂直上方５０nmの位置に基板
面に開口して配置した。Thereafter, a raw material gas was introduced. The raw material gas was CH 4 : CO 2 : H 2 = 5: 10: 85 in flow rate ratio. The microwave and electromagnet were then turned on to generate plasma. It was confirmed that the plasma was uniformly spread in the plasma generation chamber 7 of the cavity. Further, a microwave of 2.45 GHz and 500 W was applied, a surface magnetic wave propagation film having a thickness of 15 μm was formed at an applied magnetic field of 875 G, a substrate temperature of 600 ° C. and an operating pressure of 1 × 10 −3 Torr. At this time, the heating tube 3 was disposed at a position 50 nm vertically above the substrate 5 with an opening on the substrate surface.
【００３６】なお、動作圧力を０．５Torrとした以外は
上記と同様にして、比較例の表面波伝搬膜も形成した。A surface acoustic wave propagation film of a comparative example was formed in the same manner as above except that the operating pressure was set to 0.5 Torr.
【００３７】成膜終了後、冷却して基板を取り出し、こ
れらの表面波伝搬膜に対してＸ線回折を行なったとこ
ろ、ダイヤモンドが含まれていることが確認された。そ
して、５００００倍の走査型電子顕微鏡により観察した
ところ、比較例では膜表面に自形面がみられたが、本発
明例では自形面は観察されず、平坦な表面であった。ま
た、ダイヤモンドの平均結晶粒径を測定した結果、比較
例では２μm であったが本発明例では９５nmと極めて小
さかった。結晶粒径は、比較例では走査型電子顕微鏡に
より、本発明例では透過型電子顕微鏡により測定した。After completion of the film formation, the substrate was taken out after cooling, and X-ray diffraction was performed on these surface wave propagation films. As a result, it was confirmed that diamond was contained. Then, when observed with a scanning electron microscope at a magnification of 50,000, a self-shaped surface was observed on the film surface in the comparative example, but no self-shaped surface was observed in the example of the present invention, and the surface was flat. Also, as a result of measuring the average crystal grain size of diamond, it was 2 μm in the comparative example, but was extremely small at 95 nm in the present invention example. The crystal grain size was measured by a scanning electron microscope in the comparative example, and by a transmission electron microscope in the present invention example.
【００３８】次に、表面波伝搬膜上に、電子ビーム蒸着
によりＡｌ膜を形成し、フォトリソグラフィーによりエ
ッチングして、クシ型電極とした。電極周期は８μm と
した。なお、比較例のものでは、Ａｌ膜蒸着前に表面波
伝搬膜の表面をバフ研磨して平滑化した。Next, an Al film was formed on the surface wave propagation film by electron beam evaporation and etched by photolithography to obtain a comb-type electrode. The electrode period was 8 μm. In the case of the comparative example, the surface of the surface wave propagation film was buffed and smoothed before the Al film deposition.
【００３９】さらに、この上に、スパッタ法により厚さ
２μm のＺｎＯ膜を形成し、圧電膜とした。Further, a 2 μm thick ZnO film was formed thereon by a sputtering method to form a piezoelectric film.
【００４０】このようにして作製された本発明例および
比較例の弾性表面波素子を用いて、伝送特性を測定し
た。本発明の素子の結果を図５に、比較例の素子の結果
を図６に示す。本発明の素子は比較例の素子に比べ共振
周波数での振幅が大きい、すなわち挿入損失が小さい。
このことから、本発明の素子は比較例の素子に比べ伝搬
損失が小さいことがわかる。また、本発明の素子は比較
例の素子よりも零点での振幅が小さくなっており、弾性
表面波の位相のばらつきが小さいことがわかる。The transmission characteristics were measured using the surface acoustic wave devices of the present invention and the comparative examples manufactured as described above. FIG. 5 shows the results of the device of the present invention, and FIG. 6 shows the results of the device of the comparative example. The device of the present invention has a larger amplitude at the resonance frequency, that is, a smaller insertion loss than the device of the comparative example.
This indicates that the element of the present invention has smaller propagation loss than the element of the comparative example. In addition, the element of the present invention has a smaller amplitude at the zero point than the element of the comparative example, and it can be seen that the phase variation of the surface acoustic wave is smaller.
【００４１】上記した本発明の素子の他に、表面波伝搬
膜の平均結晶粒径の異なる素子を作製した。表面波伝搬
膜形成の際の圧力は、上記本発明の素子のときよりも低
くした。これらについて弾性表面波伝搬速度を測定し
た。それぞれの素子の表面波伝搬膜における平均結晶粒
径と音速とは、以下の通りであった。In addition to the above-described device of the present invention, devices having surface acoustic wave propagation films having different average crystal grain sizes were manufactured. The pressure at the time of forming the surface acoustic wave propagation film was lower than that of the device of the present invention. The surface acoustic wave propagation velocity was measured for these. The average crystal grain size and the sound velocity in the surface wave propagation film of each element were as follows.
【００４２】 [0042]
【００４３】以上の結果から本発明の効果が明らかであ
る。The effects of the present invention are clear from the above results.
【図１】本発明の弾性表面波素子の構成例を示す部分断
面図である。FIG. 1 is a partial cross-sectional view showing a configuration example of a surface acoustic wave device according to the present invention.
【図２】表面波伝搬膜の形成に好適なプラズマＣＶＤ装
置の構成図である。FIG. 2 is a configuration diagram of a plasma CVD apparatus suitable for forming a surface wave propagation film.
【図３】表面波伝搬膜の形成に好適なプラズマＣＶＤ装
置の構成図である。FIG. 3 is a configuration diagram of a plasma CVD apparatus suitable for forming a surface wave propagation film.
【図４】加熱管の斜視図である。FIG. 4 is a perspective view of a heating tube.
【図５】本発明の弾性表面波素子の伝送特性を示すグラ
フである。FIG. 5 is a graph showing transmission characteristics of the surface acoustic wave device of the present invention.
【図６】従来の弾性表面波素子の伝送特性を示すグラフ
である。FIG. 6 is a graph showing transmission characteristics of a conventional surface acoustic wave device.
１ プラズマ処理装置 ２ 原料ガス導入管 ３ 加熱管 ３１ 管体 ３５ 電極 ４ 電磁石 ５ 基板 ６ 基板ホルダ ７ プラズマ生成室 ８ 真空系 ９ マイクロ波導波管 １１ 弾性表面波素子 １２ 基板 １４ 表面波伝搬膜 １５ 圧電膜 １６ 電極 DESCRIPTION OF SYMBOLS 1 Plasma processing apparatus 2 Source gas introduction pipe 3 Heating pipe 31 Tube 35 Electrode 4 Electromagnet 5 Substrate 6 Substrate holder 7 Plasma generation chamber 8 Vacuum system 9 Microwave waveguide 11 Surface acoustic wave element 12 Substrate 14 Surface wave propagation film 15 Piezoelectric Membrane 16 electrodes
───────────────────────────────────────────────────── フロントページの続き (72)発明者 長野 克人 東京都中央区日本橋一丁目13番１号 テ ィーディーケイ株式会社内 (56)参考文献 特開 平５−90886（ＪＰ，Ａ) 特開 平３−198412（ＪＰ，Ａ) 特開 平１−103310（ＪＰ，Ａ) 特開 平２−83221（ＪＰ，Ａ) 電子情報通信学会技術研究報告Ｖｏ ｌ．88，Ｎｏ．181（ＵＳ88−38），ｐ. 43−48 (58)調査した分野(Int.Cl.7，ＤＢ名) H03H 9/25 C23C 16/50 H03H 3/08 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuto Nagano 1-13-1 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation (56) References JP-A-5-90886 (JP, A) JP-A Heisei 3-198412 (JP, A) JP-A-1-103310 (JP, A) JP-A-2-83221 (JP, A) IEICE Technical Report Vol. 88, No. 181 (US88-38), pp. 43-48 (58) Fields investigated (Int. Cl. 7 , DB name) H03H 9/25 C23C 16/50 H03H 3/08
Claims (8)
の順で有し、圧電膜に電界を印加する電極を有する弾性
表面波素子であって、 前記表面波伝搬膜が、平均結晶粒径１００nm以下のダイ
ヤモンドを含む炭素膜であることを特徴とする弾性表面
波素子。1. A surface acoustic wave device having a surface wave propagation film and a piezoelectric film on a substrate in this order, and having an electrode for applying an electric field to the piezoelectric film, wherein the surface wave propagation film has an average crystal grain size. A surface acoustic wave device comprising a carbon film containing diamond having a diameter of 100 nm or less.
以上である請求項１の弾性表面波素子。2. The diamond having an average crystal grain size of 5 nm.
The surface acoustic wave device according to claim 1, which is as described above.
s 以上である請求項１または２の弾性表面波素子。3. The sound velocity in the surface wave propagation film is 5700 m /
3. The surface acoustic wave device according to claim 1, wherein the surface acoustic wave device has a value of s or more.
波素子を製造する方法であって、 １×１０-5〜５×１０-3Torrの圧力中でプラズマＣＶＤ
法により前記表面波伝搬膜を形成することを特徴とする
弾性表面波素子の製造方法。4. The method for manufacturing a surface acoustic wave device according to claim 1, wherein said surface acoustic wave device is formed by plasma CVD at a pressure of 1 × 10 -5 to 5 × 10 -3 Torr.
A method for manufacturing a surface acoustic wave device, comprising forming the surface acoustic wave propagation film by a method.
ガスの粒子速度を増加させた後、前記ガスの分子を電
離、解離してプラズマＣＶＤを行なう請求項４の弾性表
面波素子の製造方法。5. The surface acoustic wave device according to claim 4, wherein after the raw material neutral particle gas collides with the heating element to increase the particle velocity of the gas, plasma CVD is performed by ionizing and dissociating the gas molecules. Production method.
内壁に前記ガスを衝突させる請求項５の弾性表面波素子
の製造方法。6. The method for manufacturing a surface acoustic wave device according to claim 5, wherein the heating body is a heating tube, and the gas is caused to collide with an inner wall of the heating tube.
されている請求項５または６の弾性表面波素子の製造方
法。7. The method of manufacturing a surface acoustic wave device according to claim 5, wherein the heating element is heated to a temperature of 700 K or more.
波プラズマによって行なう請求項５ないし７のいずれか
の弾性表面波素子の製造方法。8. The method for manufacturing a surface acoustic wave device according to claim 5, wherein the ionization and dissociation of the molecules are performed by a magnetic field microwave plasma.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP08570793A JP3233489B2 (en) | 1993-03-19 | 1993-03-19 | Surface acoustic wave device and method of manufacturing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP08570793A JP3233489B2 (en) | 1993-03-19 | 1993-03-19 | Surface acoustic wave device and method of manufacturing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06276049A JPH06276049A (en) | 1994-09-30 |
| JP3233489B2 true JP3233489B2 (en) | 2001-11-26 |
Family
ID=13866304
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP08570793A Expired - Fee Related JP3233489B2 (en) | 1993-03-19 | 1993-03-19 | Surface acoustic wave device and method of manufacturing the same |
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| JP (1) | JP3233489B2 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7132309B2 (en) | 2003-04-22 | 2006-11-07 | Chien-Min Sung | Semiconductor-on-diamond devices and methods of forming |
| US6814130B2 (en) * | 2000-10-13 | 2004-11-09 | Chien-Min Sung | Methods of making diamond tools using reverse casting of chemical vapor deposition |
| WO2003065575A2 (en) * | 2002-01-25 | 2003-08-07 | Michigan State University | Surface acoustic wave devices based on unpolished nanocrystalline diamond |
| US7846767B1 (en) | 2007-09-06 | 2010-12-07 | Chien-Min Sung | Semiconductor-on-diamond devices and associated methods |
| JP2012065304A (en) * | 2010-08-16 | 2012-03-29 | Seiko Epson Corp | Piezoelectric vibration device, method of manufacturing the same, and method of adjusting resonant frequency |
| EP2658123B1 (en) * | 2010-12-24 | 2019-02-13 | Murata Manufacturing Co., Ltd. | Elastic wave device and method for manufacturing the same. |
| JP6232817B2 (en) * | 2013-08-05 | 2017-11-22 | 住友電気工業株式会社 | Nano-polycrystalline diamond and tool comprising the same |
-
1993
- 1993-03-19 JP JP08570793A patent/JP3233489B2/en not_active Expired - Fee Related
Non-Patent Citations (1)
| Title |
|---|
| 電子情報通信学会技術研究報告Ｖｏｌ．８８，Ｎｏ．１８１（ＵＳ８８−３８），ｐ．４３−４８ |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06276049A (en) | 1994-09-30 |
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