JPH04150512A - Surface acoustic wave element - Google Patents
Surface acoustic wave elementInfo
- Publication number
- JPH04150512A JPH04150512A JP27492890A JP27492890A JPH04150512A JP H04150512 A JPH04150512 A JP H04150512A JP 27492890 A JP27492890 A JP 27492890A JP 27492890 A JP27492890 A JP 27492890A JP H04150512 A JPH04150512 A JP H04150512A
- Authority
- JP
- Japan
- Prior art keywords
- comb
- thin film
- acoustic wave
- surface acoustic
- electrodes
- 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.)
- Granted
Links
- 238000010897 surface acoustic wave method Methods 0.000 title claims abstract description 34
- 239000010409 thin film Substances 0.000 claims abstract description 32
- 239000000758 substrate Substances 0.000 claims description 18
- 239000010408 film Substances 0.000 claims description 14
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 7
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 7
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 3
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 2
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 2
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 2
- 238000000034 method Methods 0.000 abstract description 8
- 238000004519 manufacturing process Methods 0.000 abstract description 6
- 239000000428 dust Substances 0.000 abstract description 4
- 230000005611 electricity Effects 0.000 abstract description 4
- 230000003068 static effect Effects 0.000 abstract description 4
- 238000003466 welding Methods 0.000 abstract description 3
- 230000015556 catabolic process Effects 0.000 abstract description 2
- 238000007789 sealing Methods 0.000 abstract description 2
- 210000001520 comb Anatomy 0.000 abstract 2
- 229920002120 photoresistant polymer Polymers 0.000 description 10
- 239000011295 pitch Substances 0.000 description 10
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 7
- 229910052782 aluminium Inorganic materials 0.000 description 6
- 230000005484 gravity Effects 0.000 description 5
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000004544 sputter deposition Methods 0.000 description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000005268 plasma chemical vapour deposition Methods 0.000 description 2
- 238000007738 vacuum evaporation Methods 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
Description
本発明は、例えば通信機器用のフィルタ回路や共振器回
路として使用するのに適した表面弾性波素子に関するも
のである。The present invention relates to a surface acoustic wave element suitable for use as a filter circuit or a resonator circuit for communication equipment, for example.
圧電体に電圧を印加して生ずる表面弾性波を利用する素
子として表面弾性波素子が知られている。
第４図には、従来の表面弾性波素子本体の外観図が示し
である。この図に示すように、表面弾性波素子ｌＯは、
圧電基板１上に櫛型電極２ａと２ｂ及び櫛型電極３ａと
３ｂが形成されている。
各櫛型電極２ａはパッド部４ａにつながっており、各櫛
型電極２ｂはパッド部４ｂに、各櫛型電極３ａはパッド
部５ａに、各櫛型電極３ｂはパッド部５ｂに夫々つなが
っている。パッド部４ａは外部電極６ａに接続され、パ
ッド部４ｂは外部電極６ｂに、パッド部５ａは外部電極
７ａに、パッド部５ｂは外部電極７ｂに接続している。
第５図は櫛型電極２ａと２ｂ及びパッド部４ａと４ｂの
拡大正面図であり、櫛型電極３ａと３ｂ及びパッド部５
ａと５ｂも同じような形状をしている。第６図には櫛型
電極２ａと２ｂの断面図が示しである。櫛型電極３ａと
３ｂの断面も同じような形状をしている。櫛型電極２ａ
の各ピッチと櫛型電極２ｂの各ピッチは夫々対向し、櫛
型電極３ａの各ピッチと櫛型電極３ｂの各ピッチも夫々
対向している。横型電極２ａと２ｂおよび櫛型電極３ａ
と３ｂは通常アルミニニウム金属薄膜で、厚みが１００
０人〜５０００人程度、電極ピッチは１μｍ〜１０μｍ
程度に形成する。
この表面弾性波素子１０で櫛型電極の一対、例えば櫛型
電極２ａと２ｂ間に外部電極６ａと６ｂを通じて高周波
信号が入力すると、電極ピッチに対応した周期で圧電基
板１の表面に機械的歪が生ずる。この機械的歪は表面波
として圧電基板１の表面を伝わり、もう一方の対の櫛型
電極３ａと３ｂまで到達する。櫛型電極３ａと３ｂでは
この機械的な歪から起電力が生じ、電気信号として検出
できる。このとき櫛型電極２ａと２ｂおよび櫛型電極３
ａと３ｂのピッチに一致しない人力周波数の信号は多数
の電極ピッチで互いに打消されて伝達されず、電極ピッ
チに一致した周波数信号のみが伝達される。
上記した表面弾性波素子はフィルタ回路や共振器回路と
して使用される。表面弾性波素子を回路部品として完成
させるには、表面弾性波素子を金属性ベースに貼りつけ
たり、櫛型電極のパッドを外部接続端子にワイヤで接続
する（ワイヤボンディング）の作業や、表面弾性波素子
にキャップを被せてその周辺部を溶接封止するといった
作業が必要である。
表面弾性波素子は圧電基板を使用しているため、このよ
うな作業工程中に遭遇する機械的な摩擦や温度変化によ
り静電気を生ずることがある。
このとき櫛型電極の電極ピッチが非常に狭いため、電極
間で放電し、表面弾性波素子が放電破壊してしまうこと
があった。また、圧電基板表面の帯電により空気中のご
みを吸着しやすいので、製品に欠陥を生ずることがあっ
た。A surface acoustic wave element is known as an element that utilizes surface acoustic waves generated by applying a voltage to a piezoelectric material. FIG. 4 shows an external view of a conventional surface acoustic wave element main body. As shown in this figure, the surface acoustic wave element IO is
On a piezoelectric substrate 1, comb-shaped electrodes 2a and 2b and comb-shaped electrodes 3a and 3b are formed. Each comb-shaped electrode 2a is connected to a pad part 4a, each comb-shaped electrode 2b is connected to a pad part 4b, each comb-shaped electrode 3a is connected to a pad part 5a, and each comb-shaped electrode 3b is connected to a pad part 5b. . The pad portion 4a is connected to the external electrode 6a, the pad portion 4b is connected to the external electrode 6b, the pad portion 5a is connected to the external electrode 7a, and the pad portion 5b is connected to the external electrode 7b. FIG. 5 is an enlarged front view of the comb-shaped electrodes 2a and 2b and the pad portions 4a and 4b.
A and 5b also have similar shapes. FIG. 6 shows a cross-sectional view of the comb-shaped electrodes 2a and 2b. The cross sections of the comb-shaped electrodes 3a and 3b also have similar shapes. Comb-shaped electrode 2a
Each pitch of the comb-shaped electrode 2b and each pitch of the comb-shaped electrode 2b are opposed to each other, and each pitch of the comb-shaped electrode 3a and each pitch of the comb-shaped electrode 3b are also opposed to each other. Horizontal electrodes 2a and 2b and comb-shaped electrode 3a
and 3b are usually aluminum metal thin films with a thickness of 100 mm.
0 to 5000 people, electrode pitch 1μm to 10μm
Form to a certain degree. In this surface acoustic wave element 10, when a high frequency signal is input between a pair of comb-shaped electrodes, for example, comb-shaped electrodes 2a and 2b, through external electrodes 6a and 6b, mechanical strain is generated on the surface of the piezoelectric substrate 1 at a period corresponding to the electrode pitch. occurs. This mechanical strain is transmitted as a surface wave on the surface of the piezoelectric substrate 1 and reaches the other pair of comb-shaped electrodes 3a and 3b. This mechanical strain generates an electromotive force in the comb-shaped electrodes 3a and 3b, which can be detected as an electrical signal. At this time, the comb-shaped electrodes 2a and 2b and the comb-shaped electrode 3
Signals with human frequencies that do not match the pitches of a and 3b are canceled by each other at a large number of electrode pitches and are not transmitted, and only frequency signals that match the electrode pitches are transmitted. The surface acoustic wave device described above is used as a filter circuit or a resonator circuit. To complete a surface acoustic wave device as a circuit component, it is necessary to attach the surface acoustic wave device to a metal base, connect the comb-shaped electrode pads to external connection terminals with wires (wire bonding), and perform surface acoustic wave It is necessary to cover the element with a cap and seal the surrounding area by welding. Because surface acoustic wave devices use piezoelectric substrates, static electricity can be generated due to mechanical friction and temperature changes encountered during these operations. At this time, since the electrode pitch of the comb-shaped electrodes is very narrow, discharge may occur between the electrodes, and the surface acoustic wave element may be destroyed by discharge. In addition, since the surface of the piezoelectric substrate is electrically charged, it tends to attract dust in the air, resulting in defects in the product.
本発明は、従来の表面弾性波素子がもつ上記のような不
都合を解消するためになされたもので、製作作業工程中
に放電破壊してしまうことがない表面弾性波素子を提供
するものである。The present invention was made in order to eliminate the above-mentioned disadvantages of conventional surface acoustic wave devices, and provides a surface acoustic wave device that will not be destroyed by electrical discharge during the manufacturing process. .
上記課題を解決するための本発明を適用した表面弾性波
素子は、実施例に対応する第１図および第２図に示すよ
うに、圧電基板１上に形成された櫛型電極２ａと２ｂお
よび３ａと３ｂの対向する各欄が、直流抵抗１０’Ω〜
ｔｏ”Ωの半絶縁性薄膜１１により接続被覆されている
。
また、半絶縁性薄膜１１の比抵抗は１０’Ωｃ１１〜１
０１ΩＣ−程度であることが好ましい。A surface acoustic wave device to which the present invention is applied to solve the above problems is as shown in FIGS. Each column 3a and 3b facing each other has a DC resistance of 10'Ω~
The connection is covered by a semi-insulating thin film 11 with a resistance of 10'Ωc11 to 10'Ω.
It is preferable that the resistance is about 0.01ΩC-.
本発明の表面弾性波素子は、櫛型電極２ａと２ｂおよび
３ａと３ｂが半絶縁性薄膜１１と接続することにより、
電極間の直流抵抗が小さくなる。半絶縁性薄膜１１の比
抵抗値は、薄膜に加わる電界に依存するが５例えば圧電
基板ｌの帯電により放電する電界強度２ Ｖ ／ Ｃ＠
では、約１０”０ｃｍとなる。第１図に示すように、一
対の電極２ａ−２ｂの電極間隔なｄ、電極長さをβ、電
極本数をｎとし、電極の上部に半絶縁性薄ｌ１１１をｔ
の厚さに形成したとき、対向する各欄の直流抵抗Ｒは、
次式（１）により近似的に求められる。
ｉ
Ｒ：８８ ρ ・□・ □ ・−・・−（１）ｔｊ
ｎ
前記の電界強度２Ｖ／ａｍの場合、 ｐ ＝＝１０’
Ｑｃｗ＋、ｄ ＝ １ ｕ＋、ｔ ＝ １００＋１人、
Ａ ＝ ｌ ａｓ、 ｎ ＝ １１１００とする
とＲ＝ １０’Ωとなり、半絶縁性薄膜を使用しないと
きの電極の直流抵抗Ｒ＞ １０”Ωよりも６桁小さくな
る。従って、ワイア９の接続およびキャップ１４の溶接
封止などの作業工程中に遭遇する機械的な摩擦や温度変
化によって静電気が圧電基板１上にたまることがないの
で、電極間で放電して表面弾性波素子が放電破壊するこ
とを防止できる。
また、圧電基板表面の帯電は半絶縁性薄膜によって中和
されるため、空気中のごみも吸着しないので製造しやす
い。In the surface acoustic wave device of the present invention, the comb-shaped electrodes 2a and 2b and 3a and 3b are connected to the semi-insulating thin film 11.
DC resistance between electrodes becomes smaller. The specific resistance value of the semi-insulating thin film 11 depends on the electric field applied to the thin film.
As shown in Fig. 1, the distance between the pair of electrodes 2a and 2b is d, the electrode length is β, the number of electrodes is n, and a semi-insulating thin l111 is placed on top of the electrodes. t
When formed to a thickness of , the DC resistance R of each opposing column is
It can be approximately determined by the following equation (1). i R:88 ρ ・□・ □ ・−・・−(1)tj
n In the case of the electric field strength 2V/am, p ==10'
Qcw+, d = 1 u+, t = 100+1 person,
If A = l as, n = 11100, then R = 10'Ω, which is 6 orders of magnitude smaller than the DC resistance of the electrode R >10'Ω when no semi-insulating thin film is used. Therefore, the connection of wire 9 and the cap Since static electricity does not accumulate on the piezoelectric substrate 1 due to mechanical friction or temperature changes encountered during work processes such as welding and sealing in step 14, it is possible to prevent electrical discharge between the electrodes and damage to the surface acoustic wave element. In addition, since the electrostatic charge on the surface of the piezoelectric substrate is neutralized by the semi-insulating thin film, it does not attract dust in the air, making it easy to manufacture.
以下、本発明の実施例を図面により詳細に説明する。
！１図に示すように、表面弾性波素子１０は。
圧電基板ｌ上に横型電極２ａと２ｂおよび３ａと３ｂを
形成しである。各櫛型電極２ａはパッド部４ａにつなが
っており、各櫛型電極２ｂはパッド部４ｂに、各櫛型電
極３ａはパッド部５ａに、各櫛型電極３ｂはパッド部５
ｂに夫々つながっている。パッド部４ａは外部電極６ａ
に接続され、パッド部４ｂは外部電極６ｂに、パッド部
５ａは外部電極７ａに、パッド部５ｂは外部電極７ｂに
接続している。櫛型電極２ａと２ｂおよびパッド部４ａ
と４ｂ、櫛型電極３ａと３ｂおよびパッド部５ａと５ｂ
の拡大形状は第５図のとおりである。第２図に示しであ
るように、櫛型電極２ａと２ｂの表面を半絶縁性薄膜１
１であるシリコン窒化膜で被覆してあり、その比抵抗は
１０’Ωｃｍ〜１０９ΩＣ園程度である。櫛型電極３ａ
と３ｂの表面も同様に、比抵抗が１０４Ωｃｃｍ−１０
”Ωｃｍであるシリコン窒化膜で被覆しである。
櫛型電極２ａと２ｂおよび３ａと３ｂは、以下のような
リングラフのパターン形成法により作成される。先ず圧
電基板１にアルミニュウム薄膜を真空蒸着法又はスパッ
タ法で約３０００人形成する。
この上にフォトレジストを約１μｍの厚さに均一にコー
ティングする。そこに横型電極のパターンを有するフォ
トマスクを介して、紫外線光で照射する０次いでフォト
レジストを現像すれば、櫛型電極のパターンを残した光
照射部分が除去されアルミニュウム薄膜の表面が露出さ
れる。これをリン酸／酢酸／硝酸の混合液に浸してアル
ミニュウム薄膜の表面が露出している部分を溶解すると
フォトレジストに覆われている部分のアルミニュウム薄
膜は残る。これを水洗い後、フォトレジストを除去する
とアルミニニウム薄膜からなる櫛型電極２ａと２ｂおよ
び３ａと３ｂのパターンが形成される。
櫛型電極２ａと２ｂおよび３ａと３ｂの表面をシリコン
窒化膜１１により覆う工程は、以下のとおりである。上
記により櫛型電極のパターンが形成されている圧電基板
１上の櫛型電極２ａと２ｂおよび３ａと３ｂ以外の部分
に、同様のパターン形成法によりフォトレジストで被覆
する。そこにプラズマＣＶＤ （化学気相成長）法によ
り、圧電基板ｌの温度を２００・℃以下に保ったままで
シリコン窒化膜を約５００Å以上の厚さに形成する。次
にフォトレジストを除去すると電極部以外のシリコン窒
化膜も除去される。
最後にパッド部４ａと４ｂおよびパッド部５ａと５ｂの
電極を以下により形成する。上記により櫛型電極のパタ
ーンおよびシリコン窒化膜が形成されている圧電基板１
上のパッド部４ａと４ｂおよびパッド部５ａと５ｂに該
当する以外の部分に、同様のパターン形成法によりフォ
トレジストを被覆する。この上に真空蒸着法またはスパ
ッタ法でアルミニニウム薄膜を約５０００人形成する。
この後フォトレジストを除去するとパッド部４ａと４ｂ
およびパッド部５ａと５ｂの電極が形成できる。
上記によりできた表面弾性波素子ｌＯは、さらに以下の
工程により回路部品として完成する。第３図に示すよう
に、表面弾性波素子ｌＯは金属性ベース８に貼りつけら
れる。尚、この図に示す表面弾性波素子ｌＯは櫛型電極
２ａと２ｂが半絶縁性薄膜１２、櫛型電極３ａと３ｂが
半絶縁性薄膜１３に夫々覆われている例である。櫛型電
極２ａのパッド部４ａはワイヤ９が接続され、さらにワ
イヤ９は外部接続端子６ａに接続される。同様に櫛型電
極２ｂのパッド部４ｂは外部接続端子６ｂに、櫛型電極
３ａのパッド部５ａは外部接続端子７ａに、櫛型電極３
ｂのパッド部５ｂは外部接続端子７ｂに夫々ワイヤで接
続される。これらのワイヤボンディングが終了したら金
属性ベース８の上にキャップ１４を被せ、その周辺部を
気密にろう付けし、回路部品として完成する。 半絶縁
性薄膜として用いる材質は、表面弾性波・素子の特性が
薄膜の質量に依存するので比重が小さいものがよい、シ
リコン窒化ＩＩ （ＳＬＬ 、 ｘ ＜ ４ ）は、比
重が３．４ｇ／ｃｍ”と軽いので表面弾性波素子の特性
が劣化しない。また、半絶縁性薄膜は圧電基板表面の帯
電を効率よく中和するために比抵抗の小さいものがよい
、しかしながら、電極間の直流抵抗が約１０１Ω以下に
なると、通常用いられる電気的整合インピーダンスであ
る５０Ωもしくは７０Ωに対し、表面弾性波素子本来の
インピーダンス整合回路特性が劣化する。半絶縁性薄膜
の比抵抗は電橋構成により変化するが、通常の構成では
１０４ΩＣ−〜ｌＯ″ΩＣ−の範囲で、厚さ５００人程
度であれば電気的特性も劣化せず、櫛型電極に溜る静電
気は半絶縁性薄膜を通して潤沢に放電され、圧電基板表
面は帯電しない。
本発明で使用したシリコン窒化膜（５ｉｓＮワ）は、本
来の組成比、例えばＳｉＪ＜では絶縁抵抗が高く、比抵
抗がｔｏ”０ｃｍ以上であるが、ＳＬ組成を大きくする
ことにより導電性を上げることができる。このような特
性をもつ半絶縁性薄膜の形成方法は、以下にその方法に
ついて記す。
５ＩＩＮ１１薄膜の形成は、マイクロ波を使用したプラ
ズマＣＶＤ法により、成膜時の圧力１３ｍ＋＊ｔｏｒｒ
、ＳｉＨ，カス流量５３ＣＣＭ、 Ｎ２ガス流量２５Ｓ
ＣＣＭ、マイクロ波電力３００ｗ、圧電基板温度は基準
の条件下で行なう。これらの条件は、 ５ｉｓＮｘ薄膜
のシリコン組成比が化学量論比より多くなる条件である
。また、スパッタ法でも形成可能である。
なお、半絶縁性薄膜１１は、シリコン酸化膜（ＳｉＯｍ
、 ｘ ＜ ２ 、比重２．２ｇ／ｃｍり、シリコン酸
化窒化膜（ＳｉＯＮ、比重２．２ｇ／ａｍ”〜３．４ｇ
／ｃｍ”Ｊ 、およびシリコンカーバイト（ＳＬＣＩｌ
、 Ｘ ＜ １ 、比重３．２ｇ／ｃｎ＋３）も成膜時
の条件を変えることにより。
同様に形成できる。
τ発明の効果】
以上、説明したように本発明を適用する表面弾性波素子
は、製造作業工程中で放電破壊することを防止でき、さ
らにまたごみなどによる電極の短絡がないため、製造歩
留が飛躍的に増大するとともに品質が均一になるという
利点がある。Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. ! As shown in FIG. 1, a surface acoustic wave device 10 is. Horizontal electrodes 2a and 2b and 3a and 3b are formed on a piezoelectric substrate l. Each comb-shaped electrode 2a is connected to the pad part 4a, each comb-shaped electrode 2b is connected to the pad part 4b, each comb-shaped electrode 3a is connected to the pad part 5a, and each comb-shaped electrode 3b is connected to the pad part 5.
Each is connected to b. The pad portion 4a is an external electrode 6a
The pad portion 4b is connected to the external electrode 6b, the pad portion 5a is connected to the external electrode 7a, and the pad portion 5b is connected to the external electrode 7b. Comb-shaped electrodes 2a and 2b and pad portion 4a
and 4b, comb-shaped electrodes 3a and 3b, and pad portions 5a and 5b.
The enlarged shape of is shown in FIG. As shown in FIG. 2, the surfaces of the comb-shaped electrodes 2a and 2b are covered with a semi-insulating thin film 1.
1, and its specific resistance is approximately 10'Ωcm to 109ΩC. Comb-shaped electrode 3a
Similarly, the surface of 3b has a specific resistance of 104Ωccm-10
The comb-shaped electrodes 2a and 2b and 3a and 3b are formed by the following ring graph pattern forming method.First, a thin aluminum film is deposited on the piezoelectric substrate 1 by vacuum evaporation. Alternatively, about 3,000 layers are formed using a sputtering method. A photoresist is uniformly coated on this to a thickness of about 1 μm. A photoresist is then irradiated with ultraviolet light through a photomask having a pattern of horizontal electrodes. When developed, the light irradiated part leaving the comb-shaped electrode pattern is removed and the surface of the aluminum thin film is exposed.This is immersed in a mixed solution of phosphoric acid/acetic acid/nitric acid to expose the surface of the aluminum thin film. When the parts covered by the photoresist are dissolved, the aluminum thin film remains in the parts covered by the photoresist.After washing this with water and removing the photoresist, patterns of comb-shaped electrodes 2a and 2b and 3a and 3b made of the aluminum thin film are formed. The process of covering the surfaces of the comb-shaped electrodes 2a and 2b and 3a and 3b with the silicon nitride film 11 is as follows.The comb-shaped electrode 2a on the piezoelectric substrate 1 on which the comb-shaped electrode pattern is formed as described above. 2b, 3a, and 3b are coated with photoresist using the same pattern forming method.Then, the piezoelectric substrate 1 is coated with photoresist using a plasma CVD (chemical vapor deposition) method while keeping the temperature of the piezoelectric substrate 1 below 200°C. A silicon nitride film is formed to a thickness of about 500 Å or more.Next, when the photoresist is removed, the silicon nitride film other than the electrode parts is also removed.Finally, the electrodes of pad parts 4a and 4b and pad parts 5a and 5b are formed as follows. A piezoelectric substrate 1 on which a comb-shaped electrode pattern and a silicon nitride film are formed as described above.
Portions other than those corresponding to upper pad portions 4a and 4b and pad portions 5a and 5b are coated with photoresist by a similar pattern forming method. Approximately 5000 aluminum thin films are formed on this by vacuum evaporation or sputtering. After that, when the photoresist is removed, the pad portions 4a and 4b are removed.
And electrodes for pad portions 5a and 5b can be formed. The surface acoustic wave device 1O produced as described above is further completed as a circuit component through the following steps. As shown in FIG. 3, the surface acoustic wave element IO is attached to a metal base 8. As shown in FIG. The surface acoustic wave element IO shown in this figure is an example in which the comb-shaped electrodes 2a and 2b are covered with a semi-insulating thin film 12, and the comb-shaped electrodes 3a and 3b are covered with a semi-insulating thin film 13, respectively. A wire 9 is connected to the pad portion 4a of the comb-shaped electrode 2a, and the wire 9 is further connected to an external connection terminal 6a. Similarly, the pad portion 4b of the comb-shaped electrode 2b is connected to the external connection terminal 6b, and the pad portion 5a of the comb-shaped electrode 3a is connected to the external connection terminal 7a.
The pad portions 5b of b are respectively connected to external connection terminals 7b by wires. After these wire bondings are completed, the cap 14 is placed on the metal base 8, and the peripheral portion thereof is brazed to be airtight, thereby completing the circuit component. The material used for the semi-insulating thin film should have a low specific gravity because the surface acoustic wave/element characteristics depend on the mass of the thin film. Silicon nitride II (SLL, x < 4) has a specific gravity of 3.4 g/cm. ”, so the characteristics of the surface acoustic wave device will not deteriorate.In addition, the semi-insulating thin film should have a low resistivity in order to efficiently neutralize the charge on the surface of the piezoelectric substrate. However, the DC resistance between the electrodes is If it is less than about 101 Ω, the impedance matching circuit characteristics inherent to the surface acoustic wave element will deteriorate compared to the commonly used electrical matching impedance of 50 Ω or 70 Ω.The resistivity of the semi-insulating thin film changes depending on the electric bridge configuration. , in a normal configuration, it is in the range of 104 ΩC- to lO'' ΩC-, and if the thickness is about 500 people, the electrical characteristics will not deteriorate, and the static electricity accumulated in the comb-shaped electrode will be abundantly discharged through the semi-insulating thin film, and the piezoelectric The substrate surface is not charged. The silicon nitride film (5isN) used in the present invention has a high insulation resistance at its original composition ratio, for example, SiJ<, and has a specific resistance of 0 cm or more, but by increasing the SL composition, the conductivity can be increased. The method for forming a semi-insulating thin film with such characteristics is described below.The 5IIN11 thin film was formed by plasma CVD using microwaves at a pressure of 13m+*torr during film formation.
, SiH, gas flow rate 53CCM, N2 gas flow rate 25S
CCM, microwave power of 300 W, and piezoelectric substrate temperature are performed under standard conditions. These conditions are such that the silicon composition ratio of the 5isNx thin film is greater than the stoichiometric ratio. It can also be formed by sputtering. Note that the semi-insulating thin film 11 is a silicon oxide film (SiOm
, x < 2, specific gravity 2.2 g/cm, silicon oxynitride film (SiON, specific gravity 2.2 g/am''~3.4 g
/cm”J, and silicon carbide (SLCIl)
, X < 1, specific gravity 3.2g/cn+3) by changing the conditions during film formation. It can be formed similarly. τEffects of the Invention As explained above, the surface acoustic wave device to which the present invention is applied can prevent breakdown due to discharge during the manufacturing process, and furthermore, since there is no short circuit of electrodes due to dust etc., the manufacturing yield can be improved. This has the advantage that the quality increases dramatically and the quality becomes uniform.
第１図は本発明を適用する表面弾性波素子の斜視図、第
２図はその要部断面図、第３図は表面弾性波素子を組み
込んだ回路部品の斜視図、第４図は従来の表面弾性波素
子の斜視図、第５図は櫛型電極の拡大図、第６図は従来
の表面弾性波素子の要部断面図である。
１−・・圧電基板
２ａ、２ｂ、３ａ、３ ｂ−・・櫛型電極４ａ、４ｂ、
５ａ、５ ｂ−・・パッド部６ａ、６ｂ、７ａ、７ ｂ
−・・外部ｔＳ８・・・金属性ベース
９・・・ワイヤ
１０・・・表面弾性波素子
１１．１２．１３・・・半絶縁性薄膜
１４・・・キャップ
第３図
第４図
第５図
第６図Fig. 1 is a perspective view of a surface acoustic wave device to which the present invention is applied, Fig. 2 is a cross-sectional view of its main parts, Fig. 3 is a perspective view of a circuit component incorporating the surface acoustic wave device, and Fig. 4 is a conventional FIG. 5 is an enlarged view of a comb-shaped electrode, and FIG. 6 is a sectional view of a main part of a conventional surface acoustic wave device. 1-...Piezoelectric substrates 2a, 2b, 3a, 3b-...Comb-shaped electrodes 4a, 4b,
5a, 5b--Pad portions 6a, 6b, 7a, 7b
-...External tS8...Metallic base 9...Wire 10...Surface acoustic wave element 11.12.13...Semi-insulating thin film 14...Cap Fig. 3 Fig. 4 Fig. 5 Figure 6
Claims (2)
、直流抵抗１０＾３Ω〜１０＾９Ωの半絶縁性薄膜によ
り接続被覆されていることを特徴とする表面弾性波素子
。1. A surface acoustic wave device characterized in that each opposing comb of a comb-shaped electrode formed on a piezoelectric substrate is connected and covered with a semi-insulating thin film having a DC resistance of 10^3Ω to 10^9Ω.
窒化膜、シリコン窒化膜およびシリコンカーバイトから
選ばれる薄膜であり、その比抵抗が１０＾４Ωｃｍ〜１
０＾９Ωｃｍであることを特徴とする請求項第１項記載
の表面弾性波素子。2. The semi-insulating thin film is a thin film selected from a silicon oxide film, a silicon oxynitride film, a silicon nitride film, and a silicon carbide film, and has a specific resistance of 10^4 Ωcm to 1
The surface acoustic wave device according to claim 1, characterized in that the resistance is 0^9 Ωcm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2274928A JPH0758876B2 (en) | 1990-10-12 | 1990-10-12 | Surface acoustic wave device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2274928A JPH0758876B2 (en) | 1990-10-12 | 1990-10-12 | Surface acoustic wave device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04150512A true JPH04150512A (en) | 1992-05-25 |
| JPH0758876B2 JPH0758876B2 (en) | 1995-06-21 |
Family
ID=17548500
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2274928A Expired - Lifetime JPH0758876B2 (en) | 1990-10-12 | 1990-10-12 | Surface acoustic wave device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0758876B2 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1994021040A1 (en) * | 1993-03-11 | 1994-09-15 | Siemens Matsushita Components Gmbh & Co. Kg | Component working with acoustic surface waves |
| JPH08167826A (en) * | 1994-12-13 | 1996-06-25 | Nec Corp | Surface acoustic wave element |
| US5889446A (en) * | 1996-01-19 | 1999-03-30 | Nec Corporation | Surface acoustic wave device with a resistor thin film to remove pyroelectric effect charges |
| US6078229A (en) * | 1997-08-05 | 2000-06-20 | Nec Corporation | Surface acoustic wave device mounted with a resin film and method of making same |
| US6580198B2 (en) | 1999-11-30 | 2003-06-17 | Tdk Corporation | Surface acoustic wave device having a thin metal oxide film fully covering at least the electrodes and method of fabricating same |
| KR20130094918A (en) * | 2012-02-17 | 2013-08-27 | 삼성전자주식회사 | Nano scale resonator and nano scale sensor and fabrication method thereof |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5642418A (en) * | 1979-09-13 | 1981-04-20 | Murata Mfg Co Ltd | Bulk wave piezoelectric resonator device |
| JPS56162523A (en) * | 1980-05-19 | 1981-12-14 | Nippon Dempa Kogyo Co Ltd | Elastic surface wave device |
| JPS61191624U (en) * | 1985-05-20 | 1986-11-28 | ||
| JPH022327A (en) * | 1987-12-18 | 1990-01-08 | Univ Claude Bernard Lyon 1 | Sweetener having heterocyclic group |
-
1990
- 1990-10-12 JP JP2274928A patent/JPH0758876B2/en not_active Expired - Lifetime
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5642418A (en) * | 1979-09-13 | 1981-04-20 | Murata Mfg Co Ltd | Bulk wave piezoelectric resonator device |
| JPS56162523A (en) * | 1980-05-19 | 1981-12-14 | Nippon Dempa Kogyo Co Ltd | Elastic surface wave device |
| JPS61191624U (en) * | 1985-05-20 | 1986-11-28 | ||
| JPH022327A (en) * | 1987-12-18 | 1990-01-08 | Univ Claude Bernard Lyon 1 | Sweetener having heterocyclic group |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1994021040A1 (en) * | 1993-03-11 | 1994-09-15 | Siemens Matsushita Components Gmbh & Co. Kg | Component working with acoustic surface waves |
| US5699026A (en) * | 1993-03-11 | 1997-12-16 | Siemens Aktiengesellschaft | Component working with surface acoustic waves |
| JPH08167826A (en) * | 1994-12-13 | 1996-06-25 | Nec Corp | Surface acoustic wave element |
| US5889446A (en) * | 1996-01-19 | 1999-03-30 | Nec Corporation | Surface acoustic wave device with a resistor thin film to remove pyroelectric effect charges |
| US6078229A (en) * | 1997-08-05 | 2000-06-20 | Nec Corporation | Surface acoustic wave device mounted with a resin film and method of making same |
| US6580198B2 (en) | 1999-11-30 | 2003-06-17 | Tdk Corporation | Surface acoustic wave device having a thin metal oxide film fully covering at least the electrodes and method of fabricating same |
| KR20130094918A (en) * | 2012-02-17 | 2013-08-27 | 삼성전자주식회사 | Nano scale resonator and nano scale sensor and fabrication method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0758876B2 (en) | 1995-06-21 |
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