JPH07232998A - Dielectric material and its production - Google Patents
Dielectric material and its productionInfo
- Publication number
- JPH07232998A JPH07232998A JP2441194A JP2441194A JPH07232998A JP H07232998 A JPH07232998 A JP H07232998A JP 2441194 A JP2441194 A JP 2441194A JP 2441194 A JP2441194 A JP 2441194A JP H07232998 A JPH07232998 A JP H07232998A
- Authority
- JP
- Japan
- Prior art keywords
- substrate
- aluminum nitride
- crystal
- axis
- dielectric material
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Physical Or Chemical Processes And Apparatus (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
- Physical Vapour Deposition (AREA)
- Inorganic Insulating Materials (AREA)
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明は電子材料、特に誘電体
材料及びその製造方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic material, particularly a dielectric material, and a method for manufacturing the same.
【０００２】[0002]
【従来の技術】一般に窒化アルミニウムは圧電性、及び
電気光学効果を有する誘電体であり、電気音響変換素子
や電気光学素子などへの利用が期待されている。しかし
窒化アルミニウムは液相状態を得るのに３３００℃、１
０5 気圧と非常な高温高圧が必要であり、デバイスを構
成するのに必要な大きさの単結晶を育成することが困難
である（岩田：日本結晶学会誌、１３、１９７１、１４
１）。窒化アルミニウムをデバイスとして利用するため
には、ＰＶＤ法やＣＶＤ法の気相成長法により薄膜とし
て適当な基板上に合成することが有効である（例えば工
業材料：第３１巻第９号ｐ５５（１９８３年））。基板
としてガラスや表面酸化したシリコンなど、表面が非晶
質である基板上に成膜を行うと、結晶方位のｃ軸が基板
表面と垂直に配向した多結晶膜が得られることが知られ
ている（例えば桑野ら：金属表面技術、３８、２２８
（１９８７））。2. Description of the Related Art Generally, aluminum nitride is a dielectric having piezoelectricity and electro-optical effect, and is expected to be used for electroacoustic conversion elements, electrooptical elements, and the like. However, aluminum nitride has a temperature of 3300 ° C.
0 5 atmospheres and extremely high temperature and pressure is required, it is difficult to grow a single crystal size required to configure the device (Iwata: Crystallographic Society of Japan Journal, 13,1971,14
1). In order to utilize aluminum nitride as a device, it is effective to synthesize it as a thin film on a suitable substrate by a vapor phase growth method such as PVD method or CVD method (for example, industrial material: Vol. 31, No. 9, p55 (1983). Year)). It is known that when a film is formed on a substrate having an amorphous surface such as glass or surface-oxidized silicon as a substrate, a polycrystalline film in which the c-axis of the crystal orientation is oriented perpendicular to the substrate surface is obtained. (For example, Kuwano et al .: Metal surface technology, 38, 228
(1987)).
【０００３】しかし、窒化アルミニウム結晶粒のａ軸お
よびｂ軸は基板表面の平面に任意の方向に成長し、ａ軸
およびｂ軸方向の弾性率などの結晶異方性を有効に利用
することができない。又、この結晶異方性は、窒化アル
ミニウムを弾性表面波素子として用いる場合には、Ｃ面
（ａ軸およびｂ軸を含む結晶面）のどの方向に弾性表面
波が伝搬するかによって、その電気機械結合定数や伝搬
速度が変化することが知られている。（例えば弾性表面
波工学：電子通信情報学会１９７３年）従って結晶方位
の揃った材料を用い弾性表面波の速度が大きな方向に伝
搬するようにデバイスを構成することにより高周波で動
作するものが得られる。このように結晶異方性を利用
し、有利な方向を選択することにより素子の特性を改善
することが出来る。However, the a-axis and the b-axis of aluminum nitride crystal grains grow in any direction on the plane of the substrate surface, and it is possible to effectively utilize the crystal anisotropy such as the elastic modulus in the a-axis and the b-axis direction. Can not. Further, this crystal anisotropy depends on the direction of the surface acoustic wave in the C plane (the crystal plane including the a-axis and the b-axis) when aluminum nitride is used as the surface acoustic wave element. It is known that the mechanical coupling constant and the propagation velocity change. (For example, surface acoustic wave engineering: The Institute of Electronics, Information and Communication Engineers, 1973) Therefore, by using a material with uniform crystallographic orientation and configuring the device so that the velocity of the surface acoustic wave propagates in a large direction, a device operating at high frequency can be obtained. . In this way, by utilizing crystal anisotropy and selecting an advantageous direction, the characteristics of the device can be improved.
【０００４】この利用法として窒化アルミニウムを多結
晶膜ではなく、単結晶膜として作製する手法がある。基
板としてサファイアなどの単結晶を使用し、その表面に
窒化アルミニウムをエピタキシャル成長させることによ
り単結晶膜が得られることが知られている（例えばＴｓ
ｕｂｏｕｃｈｉ ｅｔ ａｌ，Ｐｒｏｃ．Ｕｌｔｒａｓ
ｏｎ．Ｓｙｍｐ．１９８２，３４０）。しかしこの場
合、基板が高価となり、また成膜速度なども小さくコス
トも高くなるという問題が生じる。As a method of utilizing this, there is a method of forming aluminum nitride as a single crystal film instead of a polycrystalline film. It is known that a single crystal such as sapphire is used as a substrate, and a single crystal film can be obtained by epitaxially growing aluminum nitride on the surface (for example, Ts.
ubouchi et al, Proc. Ultras
on. Symp. 1982, 340). However, in this case, there arises a problem that the substrate becomes expensive, the film forming rate is low, and the cost becomes high.
【０００５】[0005]
【発明が解決しようとする課題】本発明は、表面が非晶
質である廉価な基板上に結晶方位が互いに揃った多結晶
からなる窒化アルミニウム薄膜を作製する事により、結
晶異方性を有効に利用した低コストで高品位な弾性表面
波素子などの電子デバイスを得ることを可能とするもの
である。SUMMARY OF THE INVENTION According to the present invention, a crystal anisotropy is effectively produced by forming an aluminum nitride thin film composed of polycrystals whose crystal orientations are aligned with each other on a cheap substrate whose surface is amorphous. It is possible to obtain an electronic device such as a surface acoustic wave device of low cost and high quality used for the above.
【０００６】[0006]
【課題を解決するための手段】本発明の上記目的を達成
する手段としては、表面が非晶質である基板上に、窒化
アルミニウムをＰＶＤ法やＣＶＤ法にて成膜する際に、
結晶粒の結晶方位が互いに同じ方向に揃うのに必要なエ
ネルギーを加える方法にあり、このエネルギーを加える
方法は成膜時に基板表面に１０〜１００ｅＶの運動エネ
ルギーをもったプラズマ粒子を照射する方法にある。こ
のエネルギー照射により窒化アルミニウム結晶核が成長
し、互いに接触し柱状構造となる際に窒素およびアルミ
ニウムからなる堆積粒子の再配列がおこり、結晶粒界の
エネルギーを低くするために互いの結晶方位が揃うと考
えられる。Means for achieving the above object of the present invention include, as a means for forming aluminum nitride on a substrate having an amorphous surface by PVD or CVD,
There is a method of applying energy necessary for aligning the crystal orientations of crystal grains in the same direction, and a method of applying this energy is a method of irradiating the substrate surface with plasma particles having a kinetic energy of 10 to 100 eV. is there. This energy irradiation causes aluminum nitride crystal nuclei to grow, and when they come into contact with each other to form a columnar structure, rearrangement of the deposited particles of nitrogen and aluminum occurs, and the crystal orientations of the two are aligned to reduce the energy of the crystal grain boundaries. it is conceivable that.
【０００７】この照射する粒子の運動エネルギーが１０
ｅＶ以下の場合には堆積された窒素およびアルミニウム
原子が再配列するのに十分なエネルギーが得られず、結
晶方位が揃った柱状構造からなる多結晶膜は得られな
い。また、この照射する粒子の運動エネルギーが１００
ｅＶ以上の場合には堆積した窒化アルミニウム膜に必要
以上の衝撃を与えるために、結晶欠陥が多くなり好まし
くない。The kinetic energy of the irradiated particles is 10
In the case of eV or less, sufficient energy for rearranging the deposited nitrogen and aluminum atoms cannot be obtained, and a polycrystalline film having a columnar structure with uniform crystal orientation cannot be obtained. Also, the kinetic energy of the particles to be irradiated is 100
In the case of eV or more, the deposited aluminum nitride film is given an excessive impact, so that crystal defects are increased, which is not preferable.
【０００８】従って、目的とする結晶方位の揃った柱状
構造からなる多結晶窒化アルミニウム薄膜を得るために
は１０〜１００ｅＶの範囲の運動エネルギーをもった粒
子を照射することが有効である。この範囲のエネルギー
をもった粒子を照射する手段としてはＥＣＲスパッタに
よるプラズマ照射や、イオン銃による基板への照射など
の方法がある。又、基板としてはガラス、アルミナなど
が使用可能であるが、デバイスとしては、表面に自然酸
化膜を生成させたシリコン基板が望ましい。Therefore, it is effective to irradiate particles having a kinetic energy in the range of 10 to 100 eV in order to obtain a desired polycrystalline aluminum nitride thin film having a columnar structure having a uniform crystal orientation. As means for irradiating particles having energy in this range, there are methods such as plasma irradiation by ECR sputtering and irradiation of a substrate by an ion gun. Further, glass, alumina or the like can be used as the substrate, but the device is preferably a silicon substrate having a natural oxide film formed on its surface.
【０００９】[0009]
実施例１ 表面に自然酸化膜（厚み５ｎｍ）を有するシリコンウェ
ハーを基板とし、金属アルミニウムをターゲットとした
ＥＣＲ（電子サイクロトロン共鳴）スパッタ法により平
均６０ｅＶのアルゴンおよび窒素プラズマ粒子を基板に
照射して窒化アルミニウムを成膜した。成膜条件を表１
に示す。表１の条件で成膜された窒化アルミニウム薄膜
の透過型電子顕微鏡による断面写真を図１に示す。図１
−ａは明視野像を、また図１−ｂは（１００）回折によ
る暗視野像を示す。結晶粒径が５０ｎｍ程度の緻密な柱
状晶からなる多結晶膜であることが分かる。図２にその
電子線回折パターンを示す。この電子線回折パターンは
図３（図１に対応）の円で示した領域のものであり多数
の結晶粒の配向のしかたを表している。（００２）回折
のスポットはすべての結晶粒のｃ軸が基板表面に垂直で
あることを示し、また（１００）回折などが線状になら
ず、点状になっていることからすべての結晶粒において
ａ軸及びｂ軸がおなじ方向を向いていることが分かる。
従って、この多結晶窒化アルミニウム薄膜において、そ
れぞれの結晶粒の結晶方位が互いに揃っている。Example 1 A silicon wafer having a natural oxide film (thickness: 5 nm) on its surface was used as a substrate, and the substrate was irradiated with argon and nitrogen plasma particles having an average of 60 eV by an ECR (electron cyclotron resonance) sputtering method targeting metal aluminum, and nitriding. Aluminum was deposited. Table 1 shows film formation conditions
Shown in. FIG. 1 shows a cross-sectional photograph of an aluminum nitride thin film formed under the conditions of Table 1 by a transmission electron microscope. Figure 1
-A shows a bright field image, and FIG. 1-b shows a dark field image by (100) diffraction. It can be seen that the polycrystalline film is a dense columnar crystal having a crystal grain size of about 50 nm. FIG. 2 shows the electron beam diffraction pattern. This electron beam diffraction pattern is in the region shown by the circle in FIG. 3 (corresponding to FIG. 1) and represents the orientation of many crystal grains. The (002) diffraction spots indicate that the c-axes of all the crystal grains are perpendicular to the substrate surface, and the (100) diffraction and the like are not linear but dot-like, so all the crystal grains are It can be seen that the a-axis and the b-axis point in the same direction.
Therefore, in this polycrystalline aluminum nitride thin film, the crystal orientations of the respective crystal grains are aligned with each other.
【００１０】[0010]
【表１】 [Table 1]
【００１１】実施例２ 石英ガラスを基板とし、ＥＣＲ（電子サイクロトロン共
鳴）スパッタ法により平均６０ｅＶのアルゴンおよび窒
素プラズマ粒子を基板に照射して窒化アルミニウムを成
膜した。成膜条件を表２に示す。表２の条件で成膜され
た窒化アルミニウム薄膜を透過型電子顕微鏡および電子
線回折により解析した結果、実施例１とおなじく結晶粒
径が５０ｎｍ程度の緻密な柱状晶からなる多結晶膜であ
り、すべての結晶粒においてａ軸及びｂ軸がおなじ方向
を向いていた。従って、この多結晶窒化アルミニウム薄
膜において、それぞれの結晶粒の結晶方位が互いに揃っ
ている。Example 2 Using a quartz glass substrate, an aluminum nitride film was formed by irradiating the substrate with argon and nitrogen plasma particles having an average of 60 eV by ECR (electron cyclotron resonance) sputtering. Table 2 shows the film forming conditions. The aluminum nitride thin film formed under the conditions of Table 2 was analyzed by a transmission electron microscope and electron diffraction, and as a result, it was a polycrystalline film composed of dense columnar crystals with a crystal grain size of about 50 nm, The a-axis and the b-axis were oriented in the same direction in all the crystal grains. Therefore, in this polycrystalline aluminum nitride thin film, the crystal orientations of the respective crystal grains are aligned with each other.
【００１２】[0012]
【表２】 [Table 2]
【００１３】[0013]
【発明の効果】表面が非晶質の基板上に結晶軸が互いに
配向した窒化アルミニウム薄膜を作製することにより、
その弾性や圧電性などの結晶異方性を有効に利用する弾
性表面波素子などのデバイスが、単結晶サファイアなど
の高価な基板を用いることなく、作製可能となる。EFFECTS OF THE INVENTION By producing an aluminum nitride thin film having crystal axes oriented on a substrate whose surface is amorphous,
A device such as a surface acoustic wave element that effectively utilizes crystal anisotropy such as elasticity and piezoelectricity can be manufactured without using an expensive substrate such as single crystal sapphire.
【図１】実施例１の条件で作製した窒化アルミニウム薄
膜の断面透過電子顕微鏡写真、FIG. 1 is a cross-sectional transmission electron micrograph of an aluminum nitride thin film produced under the conditions of Example 1,
【図２】実施例１の条件で作製した窒化アルミニウム薄
膜の電子線回折パターン、2 is an electron diffraction pattern of an aluminum nitride thin film prepared under the conditions of Example 1, FIG.
【図３】図２の電子線回折に用いた領域を示す模式図で
ある。FIG. 3 is a schematic diagram showing a region used for electron beam diffraction in FIG.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｈ０３Ｈ 9/25 Ｃ 7259−5Ｊ ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Office reference number FI technical display location H03H 9/25 C 7259-5J
Claims (2)
方晶の結晶型を有し、該ｃ軸が基板表面と垂直に配向し
かつ互いの結晶粒がａ軸及びｂ軸方向が同一方向に配向
された窒化アルミニウム多結晶膜を成膜していることを
特徴とする誘電体材料。1. A substrate having an amorphous surface has a wurtzite hexagonal crystal form, the c-axis is oriented perpendicular to the substrate surface, and the crystal grains of each are in the a-axis and b-axis directions. Is formed of an aluminum nitride polycrystal film oriented in the same direction.
１０〜１００ｅＶの運動エネルギーを有するプラズマ粒
子照射を行うことを特徴とする請求項１記載の誘電体材
料の製造方法。2. The method for producing a dielectric material according to claim 1, wherein the film formation substrate is irradiated with plasma particles having a kinetic energy of 10 to 100 eV during the vapor phase growth method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2441194A JPH07232998A (en) | 1994-02-22 | 1994-02-22 | Dielectric material and its production |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2441194A JPH07232998A (en) | 1994-02-22 | 1994-02-22 | Dielectric material and its production |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH07232998A true JPH07232998A (en) | 1995-09-05 |
Family
ID=12137424
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2441194A Withdrawn JPH07232998A (en) | 1994-02-22 | 1994-02-22 | Dielectric material and its production |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07232998A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2020088281A (en) * | 2018-11-29 | 2020-06-04 | Tdk株式会社 | Piezoelectric thin film element |
-
1994
- 1994-02-22 JP JP2441194A patent/JPH07232998A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2020088281A (en) * | 2018-11-29 | 2020-06-04 | Tdk株式会社 | Piezoelectric thin film element |
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