JPS6352487B2 - - Google Patents
Info
- Publication number
- JPS6352487B2 JPS6352487B2 JP2614078A JP2614078A JPS6352487B2 JP S6352487 B2 JPS6352487 B2 JP S6352487B2 JP 2614078 A JP2614078 A JP 2614078A JP 2614078 A JP2614078 A JP 2614078A JP S6352487 B2 JPS6352487 B2 JP S6352487B2
- Authority
- JP
- Japan
- Prior art keywords
- insulator
- acoustic wave
- surface acoustic
- piezoelectric body
- film
- 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.)
- Expired
Links
- 239000012212 insulator Substances 0.000 claims description 22
- 238000010897 surface acoustic wave method Methods 0.000 claims description 19
- 239000002184 metal Substances 0.000 claims description 12
- 229910052751 metal Inorganic materials 0.000 claims description 12
- 229920002120 photoresistant polymer Polymers 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 5
- 239000000463 material Substances 0.000 description 7
- 239000000758 substrate Substances 0.000 description 5
- 238000007738 vacuum evaporation Methods 0.000 description 3
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 229910010413 TiO 2 Inorganic materials 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 239000011810 insulating material Substances 0.000 description 2
- 229910013641 LiNbO 3 Inorganic materials 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005566 electron beam evaporation Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
Landscapes
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Description
【発明の詳細な説明】
本発明は弾性表面波素子の構造及びその構造方
法に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a structure of a surface acoustic wave element and a method of constructing the same.
従来、圧電体物質の表面にインターデジタル形
電極を有する弾性表面波フイルターがある。その
代表的な構造は、第１図に示すように圧電体１上
に、トランスデユーサ、例えば、インターデジタ
ル形入力および出力電極２，３を設けて、電気信
号を表面波にまた、表面波を電気信号に変換して
所望の周波数特性を持つ弾性表面波フイルターを
形成している。 Conventionally, there are surface acoustic wave filters having interdigitated electrodes on the surface of a piezoelectric material. A typical structure thereof is to provide a transducer, for example, interdigital type input and output electrodes 2 and 3 on a piezoelectric body 1, as shown in FIG. is converted into an electrical signal to form a surface acoustic wave filter with desired frequency characteristics.
なお第１図ｂは第１図ａの−′における断
面図を示す。 Note that FIG. 1b shows a sectional view taken along the line -' of FIG. 1a.
また、このような弾性表面波フイルターにおい
て第２図に示すように、圧電体１とインターデジ
タル形電極２，３との間に絶縁物４を介在させた
構造の弾性表面波フイルターが提案されておりそ
の特徴として、
(1) 電気−機械結合係数を下げることにより不要
波の発生を削減できる。 Furthermore, as shown in FIG. 2, a surface acoustic wave filter has been proposed in which an insulator 4 is interposed between a piezoelectric body 1 and interdigital electrodes 2 and 3. Its features are: (1) Generation of unnecessary waves can be reduced by lowering the electro-mechanical coupling coefficient.
(2) 圧電体と絶縁物のそれぞれの温度係数を相殺
関係に選ぶことにより、圧電体単体で用いるよ
りも温度係数を小さくすることができる。(2) By selecting the temperature coefficients of the piezoelectric material and the insulating material so that they cancel each other out, the temperature coefficient can be made smaller than when the piezoelectric material is used alone.
(3) 比誘電率を小さくできインピーダンスマツチ
ングがとりやすい。(3) The dielectric constant can be reduced, making impedance matching easier.
すなわち比誘電率が大き過ぎると、インターデ
ジタル電極の入出力インピーダンスが小さくな
り、周辺回路とのインピーダンスマツチングがと
りにくいため比誘電率をより小さくする必要があ
る。そこで、より小さな比誘電率をもつ絶縁物を
圧電体上に形成すると、素子としての比誘電率を
小さくすることができる。 That is, if the relative dielectric constant is too large, the input/output impedance of the interdigital electrode becomes small, making it difficult to achieve impedance matching with peripheral circuits, so it is necessary to make the relative dielectric constant smaller. Therefore, by forming an insulator with a smaller dielectric constant on the piezoelectric material, the dielectric constant of the element can be reduced.
以上のように、圧電体１とインターデジタル形
電極２，３の間に絶縁物４を形成した構造をもつ
第２図に示すような弾性表面波フイルターには多
くの利点があるが、第１図に示す従来の構造の弾
性表面波フイルターに比べて、圧電体１上に絶縁
物４を形成するため、その工数増加に伴なうコス
トアツプの問題がある。また、圧電体１上に絶縁
物４を一面に形成するため、基板としての音波伝
播速度が変化して、その結果素子の周波数特性に
おいて中心周波数の変動が発生する問題もある。 As mentioned above, the surface acoustic wave filter shown in FIG. 2, which has a structure in which an insulator 4 is formed between a piezoelectric body 1 and interdigital electrodes 2 and 3, has many advantages. Compared to the surface acoustic wave filter of the conventional structure shown in the figure, since the insulator 4 is formed on the piezoelectric body 1, there is a problem of increased cost due to an increase in the number of steps. Furthermore, since the insulator 4 is formed all over the piezoelectric body 1, the sound wave propagation velocity of the substrate changes, and as a result, there is a problem that the center frequency changes in the frequency characteristics of the element.
本発明は、上記問題点を解決するためになされ
たもので圧電体上にインターデジタル形の絶縁物
を形成しその上に同一形状のインターデジタル形
電極を設けた弾性表面波素子及びその製造方法を
提供するものである。本発明は圧電体上に絶縁膜
を一面に形成する第２図の構造と異り、絶縁物が
ストライプ状であるため基板としての音波伝播速
度の変化が少なく、中心周波数の変動が少なくで
き、周波数特性の向上がはかれる。またそのこと
によりインターデジタル形電極の寸法設計も容易
になる。加えて、従来の弾性表面波フイルタと同
程度のコストで製作が可能である等の特徴を有す
る。 The present invention has been made to solve the above problems, and the present invention is a surface acoustic wave element in which an interdigital type insulator is formed on a piezoelectric body and an interdigital type electrode of the same shape is provided thereon, and a method for manufacturing the same. It provides: Unlike the structure shown in FIG. 2 in which an insulating film is formed all over the piezoelectric material, the present invention has a striped insulating material, so there is little change in the sound wave propagation velocity as a substrate, and the fluctuation in the center frequency can be reduced. The frequency characteristics can be improved. This also facilitates the dimensional design of the interdigital electrodes. In addition, it has features such as being able to be manufactured at a cost comparable to that of conventional surface acoustic wave filters.
次に、まず従来例として第２図に示す構造をも
つ弾性表面波フイルターを製作する方法の一例を
説明すると、まず、圧電体１（例えば、PZT、
LiNbO3等）に絶縁物４（例えば、SiO2、TiO2
等）をスパツタリング法、電子ビーム蒸着法、
CVD法等の手段により、100〜4000Å程度の膜厚
に形成する。次に、絶縁膜４上一面に金属膜（例
えば、Al、Cr−Al、Cr−Au）を真空蒸着法によ
り形成し、次に、金属膜上に、ホトレジスト膜パ
ターンを形成し、次に、ホトレジスト膜パターン
を保護膜として、金属膜を所定のエツチング液に
よりエツチングする。次に、金属膜上からホトレ
ジスト膜を取除いて弾性表面波素子が完成する。 Next, an example of a conventional method for manufacturing a surface acoustic wave filter having the structure shown in FIG. 2 will be explained.
LiNbO 3 etc.) and an insulator 4 (e.g. SiO 2 , TiO 2
etc.) by sputtering method, electron beam evaporation method,
The film is formed to a thickness of approximately 100 to 4000 Å by means such as CVD. Next, a metal film (for example, Al, Cr-Al, Cr-Au) is formed over the entire surface of the insulating film 4 by vacuum evaporation, a photoresist film pattern is formed on the metal film, and then, Using the photoresist film pattern as a protective film, the metal film is etched with a predetermined etching solution. Next, the photoresist film is removed from the metal film to complete the surface acoustic wave device.
次に、本発明の弾性表面波フイルターの構造と
製作法について説明する。 Next, the structure and manufacturing method of the surface acoustic wave filter of the present invention will be explained.
本発明の弾性表面波フイルターの構造は、第３
図に示すように、圧電体１上に、インターデジタ
ル形の絶縁物５を形成し、絶縁物５上に、絶縁物
５と同形状の金属膜２及び３からなるインターデ
ジタル形電極を設けたものである。 The structure of the surface acoustic wave filter of the present invention has a third
As shown in the figure, an interdigital insulator 5 is formed on a piezoelectric body 1, and an interdigital electrode made of metal films 2 and 3 having the same shape as the insulator 5 is provided on the insulator 5. It is something.
次に本発明の構造をもつ弾性表面波フイルター
を製作する方法の一例を第４図イ〜ニに基づいて
説明すると、まず第４図イに示す圧電体１（例え
ば、PZT、LiNbO3等）上に、第４図ロに示す通
り、インターデジタル形電極を形成する部分を欠
除部とするように、ホトレジスト膜６を形成す
る。 Next, an example of a method for manufacturing a surface acoustic wave filter having the structure of the present invention will be explained based on FIGS . As shown in FIG. 4B, a photoresist film 6 is formed on the photoresist film 6 so that the portion where the interdigital electrode is to be formed is a cutout.
次に、真空蒸着装置のベルジヤー内にこの基板
をセツトし、第４図ハに示すように、絶縁物５
（例えば、SiO2膜、TiO2膜）を、ホトレジスト膜
６によるパターンが形成された圧電体１上に、
100〜4000Å程度の膜厚で蒸着し、更に、この絶
縁物５上に、順次金属膜２，３（例えば、Al、
Cr−Al、Cr−Au膜等）を1000〜5000Å程度の膜
厚で真空蒸着する。ただし、金属膜２及び３は同
一物質であり同時に形成される。 Next, this substrate is set in the bell gear of the vacuum evaporation apparatus, and as shown in FIG.
(for example, SiO 2 film, TiO 2 film) on the piezoelectric body 1 on which the pattern of the photoresist film 6 is formed.
The metal films 2 and 3 (for example, Al,
Cr-Al, Cr-Au film, etc.) is vacuum deposited to a thickness of approximately 1000 to 5000 Å. However, metal films 2 and 3 are made of the same material and are formed at the same time.
次に、真空蒸着装置ベルジヤー内より、この基
板を取出し、圧電体１上から所定のエツチング液
により、ホトレジスト膜６を取除く。この時、ホ
トレジスト膜６上に付着している絶縁物５及び金
属膜３も同時に圧電体１上から取除かれ、圧電体
１上には、第４図ニのようにホトレジスト膜６と
はネガ関係の、絶縁物５及びその上に同一形状の
インターデジタル電極３が完成する。 Next, this substrate is taken out of the vacuum evaporation apparatus bell gear, and the photoresist film 6 is removed from the piezoelectric body 1 using a predetermined etching solution. At this time, the insulator 5 and metal film 3 adhering to the photoresist film 6 are also removed from the piezoelectric body 1 at the same time, and the photoresist film 6 is in a negative state on the piezoelectric body 1 as shown in FIG. A related insulator 5 and an interdigital electrode 3 of the same shape are completed thereon.
以上のように、本発明によれば、圧電体上に、
インターデジタル形電極と同一形状の絶縁物、そ
して、絶縁物上にインターデジタル形電極を形成
した弾性表面波素子で、電気−機械結合係数を下
げることができ、不要波の発生を削減することが
できる。また比誘電率を小さくできるのでインピ
ーダンスマツチングが容易であり、さらに圧電体
と絶縁物の温度係数を適当に選ぶことにより温度
特性の改善がはかれる。 As described above, according to the present invention, on the piezoelectric body,
A surface acoustic wave element with an insulator having the same shape as the interdigital electrode and an interdigital electrode formed on the insulator can lower the electrical-mechanical coupling coefficient and reduce the generation of unnecessary waves. can. Furthermore, since the dielectric constant can be made small, impedance matching is easy, and temperature characteristics can be improved by appropriately selecting the temperature coefficients of the piezoelectric material and the insulator.
さらに、本発明では同一蒸着装置で、絶縁膜及
び金属膜の形成が可能であり、従来の構造のもの
に比較し製作工程が少なく、コストの低下が図れ
る。加えて、本発明の構造の場合、絶縁膜がスト
ライプ状に形成されているため、基板の音波伝播
速度の絶縁膜による変動が少ないため、周波数特
性の改善、インターデジタル電極の寸法制御の際
の自由度が増加する利点もある。 Furthermore, in the present invention, it is possible to form an insulating film and a metal film using the same vapor deposition apparatus, and there are fewer manufacturing steps than those with a conventional structure, thereby reducing costs. In addition, in the case of the structure of the present invention, since the insulating film is formed in a striped shape, there is little variation in the sound wave propagation velocity of the substrate due to the insulating film, which makes it easier to improve frequency characteristics and control the dimensions of interdigital electrodes. There is also the advantage of increased degrees of freedom.
第１図ａは弾性表面波フイルターの構成を示す
平面図、同ｂは同断面図、第２図は従来の弾性表
面波フイルターの構造を示す断面図、第３図は本
発明の実施例における弾性表面波フイルターの構
造を示す断面図、第４図イ〜ニは本発明の弾性表
面波フイルターの一製造法を順に示す断面図であ
る。
１……圧電体、２，３……インターデジタル形
電極、４，５……絶縁物、６……ホトレジスト
膜。
FIG. 1a is a plan view showing the configuration of a surface acoustic wave filter, FIG. 1b is a sectional view thereof, FIG. 2 is a sectional view showing the structure of a conventional surface acoustic wave filter, and FIG. FIGS. 4A to 4D are cross-sectional views showing the structure of a surface acoustic wave filter. FIGS. 1... Piezoelectric body, 2, 3... Interdigital electrode, 4, 5... Insulator, 6... Photoresist film.
Claims (1)
を形成し、前記絶縁物の上に前記絶縁物と同一形
状の金属膜を形成したことを特徴とする弾性表面
波素子。 ２ 圧電体表面に、インターデジタル形電極パタ
ーンとはネガ関係にあるホトレジスト膜パターン
を形成する工程と、これらの表面に絶縁物を形成
する工程と、絶縁物の表面に金属膜を形成する工
程と、ホトレジスト膜と、不要な絶縁物、および
金属膜とを同時に取除く工程とを有することを特
徴とする弾性表面波素子の製造方法。[Scope of Claims] 1. A surface acoustic wave device characterized in that an interdigital insulator is formed on one surface of a piezoelectric body, and a metal film having the same shape as the insulator is formed on the insulator. 2. A step of forming a photoresist film pattern having a negative relationship with the interdigital electrode pattern on the surface of the piezoelectric body, a step of forming an insulator on these surfaces, and a step of forming a metal film on the surface of the insulator. A method for manufacturing a surface acoustic wave device, comprising the steps of simultaneously removing a photoresist film, an unnecessary insulator, and a metal film.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2614078A JPS54118150A (en) | 1978-03-07 | 1978-03-07 | Elastic surface wave element and method of fabricating same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2614078A JPS54118150A (en) | 1978-03-07 | 1978-03-07 | Elastic surface wave element and method of fabricating same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS54118150A JPS54118150A (en) | 1979-09-13 |
| JPS6352487B2 true JPS6352487B2 (en) | 1988-10-19 |
Family
ID=12185234
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2614078A Granted JPS54118150A (en) | 1978-03-07 | 1978-03-07 | Elastic surface wave element and method of fabricating same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS54118150A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008078739A (en) * | 2006-09-19 | 2008-04-03 | Fujitsu Media Device Kk | Elastic wave device and filter |
| WO2014192614A1 (en) * | 2013-05-27 | 2014-12-04 | 株式会社村田製作所 | Surface acoustic wave device |
-
1978
- 1978-03-07 JP JP2614078A patent/JPS54118150A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS54118150A (en) | 1979-09-13 |
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