JPH0222564B2 - - Google Patents
Info
- Publication number
- JPH0222564B2 JPH0222564B2 JP21114884A JP21114884A JPH0222564B2 JP H0222564 B2 JPH0222564 B2 JP H0222564B2 JP 21114884 A JP21114884 A JP 21114884A JP 21114884 A JP21114884 A JP 21114884A JP H0222564 B2 JPH0222564 B2 JP H0222564B2
- Authority
- JP
- Japan
- Prior art keywords
- acoustic wave
- surface acoustic
- insulating film
- interdigital electrode
- tantalum pentoxide
- 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
- 238000010897 surface acoustic wave method Methods 0.000 claims description 28
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 claims description 13
- 239000000758 substrate Substances 0.000 claims description 13
- PBCFLUZVCVVTBY-UHFFFAOYSA-N tantalum pentoxide Inorganic materials O=[Ta](=O)O[Ta](=O)=O PBCFLUZVCVVTBY-UHFFFAOYSA-N 0.000 claims description 13
- 239000010408 film Substances 0.000 description 16
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000007747 plating Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000004544 sputter deposition Methods 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000001259 photo etching Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 238000001039 wet etching Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02818—Means for compensation or elimination of undesirable effects
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
- H03H9/02—Details
- H03H9/05—Holders or supports
- H03H9/10—Mounting in enclosures
- H03H9/1064—Mounting in enclosures for surface acoustic wave [SAW] devices
- H03H9/1071—Mounting in enclosures for surface acoustic wave [SAW] devices the enclosure being defined by a frame built on a substrate and a cap, the frame having no mechanical contact with the SAW device
Landscapes
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Description
【発明の詳細な説明】
「技術分野」
本発明は遅延線、発振器、フイルタなどに適用
される弾性表面波素子に関する。DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a surface acoustic wave device applied to delay lines, oscillators, filters, etc.
「従来技術とその問題点」
弾性表面波素子は、従来軍需用の特殊な用途に
使用されていたが、近年FMチユーナ、TV等の
民生用機器にも使用され始め、にわかに脚光を浴
びるようになつてきた。弾性表面波素子は具体的
には遅延素子、発振子、フイルタなどとして製品
化されている。これら各種の弾性表面波素子の特
徴は、小型、軽量で、信頼性が高いこと、および
その製造工程が集積回路と類似しており、量産性
に富むことなどである。そして、現在では次くべ
からざる電子部品として量産されるに至つてい
る。"Prior Art and Its Problems" Surface acoustic wave elements have traditionally been used for special military purposes, but in recent years they have begun to be used in consumer equipment such as FM tuners and TVs, and have suddenly come into the spotlight. I'm getting old. Specifically, surface acoustic wave elements are commercialized as delay elements, oscillators, filters, and the like. The characteristics of these various surface acoustic wave devices are that they are small, lightweight, and highly reliable, and that their manufacturing process is similar to that of integrated circuits, making them highly suitable for mass production. Nowadays, it is mass-produced as an indispensable electronic component.
従来の弾性表面波素子の一例を弾性表面波共振
子を例として説明すると、第４図および第５図に
示すように、圧電基板１の上に導電性物質からな
るすだれ状電極２が形成されている。この場合、
圧電基板１は、例えば水晶、ニオブ酸リチウムな
どの圧電性をもつた単結晶や圧電セラミツクス、
あるいはガラスの表面に圧電性をもつた薄膜を形
成したものが使用される。また、すだれ状電極２
は、例えばアルミニウム、金などの金属を圧電基
板１の上に蒸着後、フオトエツチングにより形成
することができる。そして、このすだれ状電極２
の両側に誘電体、導電体、溝等からなるリツジで
構成される１対の格子状反射器３，３が形成され
ている。 To explain an example of a conventional surface acoustic wave element using a surface acoustic wave resonator as an example, as shown in FIGS. 4 and 5, an interdigital electrode 2 made of a conductive material is formed on a piezoelectric substrate 1. ing. in this case,
The piezoelectric substrate 1 is made of, for example, crystal, piezoelectric single crystal such as lithium niobate, piezoelectric ceramics,
Alternatively, a glass surface with a piezoelectric thin film formed thereon is used. In addition, the interdigital electrode 2
can be formed by photo-etching after depositing a metal such as aluminum or gold on the piezoelectric substrate 1. And this interdigital electrode 2
A pair of lattice-like reflectors 3, 3 each consisting of a ridge made of a dielectric, a conductor, a groove, etc. are formed on both sides of the lattice.
すだれ状電極２に特定周波数の電圧を印加する
と、すだれ状電極２の間隙の圧電基板１表面に電
界がかかり、圧電基板１の圧電性により電圧に比
例したひずみが生じ、そのひずみが圧電基板１の
材料によつて定まつた音速で表面波として両側に
伝搬する。この表面波は、両側の格子状反射器
３，３によつて反射され、再びすだれ状電極２に
帰還して共振がなされるようになつている。 When a voltage of a specific frequency is applied to the interdigital electrodes 2, an electric field is applied to the surface of the piezoelectric substrate 1 in the gap between the interdigital electrodes 2, and a strain proportional to the voltage is generated due to the piezoelectricity of the piezoelectric substrate 1. The sound propagates on both sides as a surface wave at a speed determined by the material. This surface wave is reflected by the grating reflectors 3, 3 on both sides, returns to the interdigital electrode 2 again, and resonates.
ところで、これら各種の弾性表面波素子は、第
６図に示すようなハーメチツクシール４と呼ばれ
る金属製容器によつて封止されるのが一般的であ
る。ハーメチツクシール４は封止性、耐触性等を
考慮して、通常はニツケルメツキ等のメツキが施
されている。 By the way, these various surface acoustic wave elements are generally sealed with a metal container called a hermetic seal 4 as shown in FIG. The hermetic seal 4 is usually plated with nickel plating or the like in consideration of sealing properties, contact resistance, etc.
しかしながら、かかる従来の弾性表面波素子に
おいては、ハーメチツクシール４の封止前に混入
した導電性異物や、ハーメチツクシール等のメツ
キ剥離物等がすだれ状電極に付着し、電極間短絡
現象を起すことがあつた。このため、電気的イン
ピーダンスが変化するなどの支障が生じ、弾性表
面波素子の信頼性が低下し、量産を妨げていた。 However, in such conventional surface acoustic wave elements, conductive foreign matter mixed in before the hermetic seal 4 is sealed, or peeled off plating of the hermetic seal, etc., adhere to the interdigital electrodes, causing short-circuits between the electrodes. A phenomenon occurred. This causes problems such as changes in electrical impedance, lowers the reliability of the surface acoustic wave element, and hinders mass production.
「発明の目的」
本発明の目的は、ハーメチツクシールのメツキ
剥離物やその他の導電性異物による電極間短絡現
象が生じないようにした弾性表面波素子を提供す
ることにある。OBJECT OF THE INVENTION An object of the present invention is to provide a surface acoustic wave device that is free from short-circuiting between electrodes due to peeled off plating of a hermetic seal or other conductive foreign matter.
「発明の構成」
本発明によれば、すだれ状電極部分に五酸化タ
ンタルからなる絶縁膜が被覆されている。"Structure of the Invention" According to the present invention, the interdigital electrode portion is coated with an insulating film made of tantalum pentoxide.
弾性表面波素子において圧電基板上を表面波が
伝搬するので、一般的には圧電基板上に絶縁膜を
被覆すると表面波の伝搬が妨げられ、弾性表面波
素子の特性が低下すると考えられる。しかし、弾
性表面波素子のすだれ状電極部分にのみ絶縁膜を
被覆した場合には、弾性表面波素子の特性低下を
無視できる程度あるいは設計上対応できる程度に
抑えられることが分つた。そして、弾性表面波素
子のすだれ状電極部分に絶縁膜を被覆することに
よつて、すだれ状電極の電極間短絡現象はほぼ完
全に防止することができ、弾性表面波素子の信頼
性を向上させると共に量産化において非常に有利
となる。 Since surface waves propagate on a piezoelectric substrate in a surface acoustic wave element, it is generally thought that coating the piezoelectric substrate with an insulating film impedes the propagation of the surface waves and deteriorates the characteristics of the surface acoustic wave element. However, it has been found that when only the interdigital electrode portions of the surface acoustic wave element are coated with an insulating film, the deterioration in the characteristics of the surface acoustic wave element can be suppressed to a negligible level or to an extent that can be accommodated in the design. By coating the interdigital electrode portion of the surface acoustic wave element with an insulating film, short-circuiting between the interelectrode of the interdigital electrode can be almost completely prevented, improving the reliability of the surface acoustic wave element. This is also very advantageous in mass production.
そして、本発明においては、すだれ状電極部分
を被覆する絶縁膜として五酸化タンタルを用い
る。すなわち、絶縁膜として種々の物質を用いて
実験した結果、特に五酸化タンタルを用いた場合
には、弾性表面波素子の特性低下が極めて小さく
抑えることができ、しかもすだれ状電極の電極間
短絡現象を効果的に防止できることが判明した。
五酸化タンタルの被覆膜は、例えばスパツタ蒸着
により形成することができる。 In the present invention, tantalum pentoxide is used as the insulating film covering the interdigital electrode portion. In other words, as a result of experiments using various materials as the insulating film, it has been found that when tantalum pentoxide is used in particular, the deterioration of the characteristics of the surface acoustic wave device can be suppressed to an extremely small level, and the short circuit phenomenon between the interelectrode of the interdigital electrode can be suppressed. It was found that this can be effectively prevented.
The tantalum pentoxide coating can be formed, for example, by sputter deposition.
「発明の実施例」
第１図および第２図に示すように、鏡面研磨を
施した水晶基板１の上にスパツタ法によりAIを
1μmの厚さで蒸着し、これを通常の湿式エツチン
グ法によりエツチングしてすだれ状電極２および
反射器３を形成した。その上に、五酸化タンタル
を、基板加熱温度200℃、成膜レート0.9μm／hr.、
Ar＋02の混合ガスで全圧２×10-3Torrにて基板
１を自公転しながらスパツタ蒸着した。そして、
すだれ状電極２の部分以外の五酸化タンタルを除
去して五酸化タンタルの絶縁膜５を形成した。こ
うして、弾性表面波共振子を製造した。``Embodiment of the invention'' As shown in FIGS. 1 and 2, AI is applied by sputtering onto a mirror-polished crystal substrate 1.
The film was deposited to a thickness of 1 μm and etched using a conventional wet etching method to form the interdigital electrode 2 and the reflector 3. On top of that, tantalum pentoxide was applied at a substrate heating temperature of 200℃ and a film formation rate of 0.9μm/hr.
Sputter deposition was performed using a mixed gas of Ar+0 2 at a total pressure of 2×10 −3 Torr while rotating the substrate 1 around its axis. and,
The tantalum pentoxide other than the interdigital electrode 2 was removed to form an insulating film 5 of tantalum pentoxide. In this way, a surface acoustic wave resonator was manufactured.
さらに、すだれ状電極２の電極間短絡現象の防
止効果を調べるため、マスク蒸着法により、すだ
れ状電極２の部分にAIを200Åの厚さでスパツタ
蒸着し、擬似導電性異物６を形成した、擬似導電
性異物６は、すだれ状電極２にまたがる大きさの
もので、すだれ状電極２を被覆する五酸化タンタ
ルの絶縁膜５の上の任意の場所に数個付着させ
た。そして、この擬似導電性異物６をすだれ状電
極２の電極間短絡現象の検討に用いた。なお、こ
の試験方法は、従来より用いられている振動試験
によるものと比較して少ない数量でより確実かつ
厳密に検査できる方法であることが実験より分つ
た。 Furthermore, in order to investigate the effect of preventing inter-electrode short circuit phenomenon of the interdigital electrode 2, AI was sputter-deposited to a thickness of 200 Å on the interdigital electrode 2 by mask deposition method to form pseudo-conductive foreign matter 6. Several pseudo-conductive foreign substances 6 were large enough to span the interdigital electrodes 2, and were attached to arbitrary locations on the tantalum pentoxide insulating film 5 covering the interdigital electrodes 2. Then, this pseudo-conductive foreign material 6 was used to study the short-circuit phenomenon between the interelectrode of the interdigital electrode 2. It has been found through experiments that this testing method allows for more reliable and rigorous testing with a smaller number of products than the conventionally used vibration testing method.
次に、上記の弾性表面波共振子を五酸化タンタ
ルの絶縁膜５の厚さを1000Å，2000Å，3000Åと
変えて作成し、それぞれについて、すだれ状電極
間の直流抵抗不良率と、共振抵抗増加率とを測定
した。なお、実験に用いた弾性表面波共振子は
90MHz帯のものである。その結果を第３図に示
す。 Next, the above-mentioned surface acoustic wave resonator was created by changing the thickness of the tantalum pentoxide insulating film 5 to 1000 Å, 2000 Å, and 3000 Å, and for each, the DC resistance failure rate between the interdigital electrodes and the resonance resistance increase The rate was measured. The surface acoustic wave resonator used in the experiment was
It is in the 90MHz band. The results are shown in FIG.
第３図から明らかなように、五酸化タンタルか
らなる絶縁膜５の膜厚が1000ÅだとAlの擬似導
電性異物６による直流抵抗不良率が平均５％程度
あるが、絶縁膜５の膜厚を2000Åにすると直流抵
抗不良率は零になり、顕著な効果が示される。ま
た、絶縁膜５の膜厚が2000Åのときの共振抵抗増
加率は８％程度であり、無視できるかあるいは設
計上対応できる程度で、実際上問題のないことが
わかる。なお、走査型電子顕微鏡、Ｘ線マイクロ
アナライザーによつて分析した結果、電極間短絡
現象を起こす導電性異物は種々のものがあるが、
主にハーメチツクシールのメツキ剥離物であるこ
とが確認された。 As is clear from FIG. 3, when the thickness of the insulating film 5 made of tantalum pentoxide is 1000 Å, the DC resistance failure rate due to the pseudo-conductive foreign matter 6 of Al is about 5% on average, but the thickness of the insulating film 5 When is set to 2000 Å, the DC resistance defect rate becomes zero, showing a remarkable effect. Further, when the thickness of the insulating film 5 is 2000 Å, the increase rate of the resonance resistance is about 8%, which is negligible or can be accommodated in the design, and there is no problem in practice. In addition, as a result of analysis using a scanning electron microscope and an X-ray microanalyzer, there are various conductive foreign substances that cause short circuits between electrodes.
It was confirmed that this was mainly peeled off plating from the hermetic seal.
「発明の効果」
以上説明したように、本発明によれば、圧電基
板上のすだれ状電極部分を五酸化タンタルからな
る絶縁膜で被覆したので、弾性表面波素子の特性
低下をおこすことなく、すだれ状電極の電極間短
絡現象をほぼ完全に防止して弾性表面波素子の信
頼性を高めることができ、量産に際して不良品の
発生を少なくすると共に検査等の作業を簡略化す
ることができる。"Effects of the Invention" As explained above, according to the present invention, since the interdigital electrode portion on the piezoelectric substrate is coated with an insulating film made of tantalum pentoxide, The reliability of the surface acoustic wave device can be improved by almost completely preventing the inter-electrode short-circuit phenomenon of the interdigital electrodes, and it is possible to reduce the occurrence of defective products during mass production and simplify inspection and other operations.
第１図は本発明による弾性表面波共振子の一実
施例を示す断面図、第２図は同弾性表面波共振子
の平面図、第３図は同弾性表面波共振子の試験結
果を示す図表、第４図は従来の弾性表面波共振子
の一例を示す平面図、第５図は同弾性表面波共振
子の断面図、第６図は弾性表面波素子をハーメチ
ツクシールで封止した製品形態を示す斜視図であ
る。
図中、１は圧電基板、２はすだれ状電極、５は
五酸化タンタルからなる絶縁膜である。
Fig. 1 is a cross-sectional view showing an embodiment of the surface acoustic wave resonator according to the present invention, Fig. 2 is a plan view of the surface acoustic wave resonator, and Fig. 3 shows test results of the surface acoustic wave resonator. Figure 4 is a plan view showing an example of a conventional surface acoustic wave resonator, Figure 5 is a cross-sectional view of the same surface acoustic wave resonator, and Figure 6 is a surface acoustic wave element sealed with a hermetic seal. FIG. In the figure, 1 is a piezoelectric substrate, 2 is an interdigital electrode, and 5 is an insulating film made of tantalum pentoxide.
Claims (1)
面波素子において、前記すだれ状電極部分に五酸
化タンタルからなる絶縁膜を被覆したことを特徴
とする弾性表面波素子。1. A surface acoustic wave device in which interdigital electrodes are formed on a piezoelectric substrate, characterized in that the interdigital electrode portions are coated with an insulating film made of tantalum pentoxide.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21114884A JPS6189708A (en) | 1984-10-08 | 1984-10-08 | Surface acoustic wave element |
| US06/779,223 US4617487A (en) | 1984-09-22 | 1985-09-23 | Piezoelectric elastic surface wave element with film of tantalum pentoxide or silicon nitride |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21114884A JPS6189708A (en) | 1984-10-08 | 1984-10-08 | Surface acoustic wave element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6189708A JPS6189708A (en) | 1986-05-07 |
| JPH0222564B2 true JPH0222564B2 (en) | 1990-05-21 |
Family
ID=16601169
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP21114884A Granted JPS6189708A (en) | 1984-09-22 | 1984-10-08 | Surface acoustic wave element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6189708A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0738425B2 (en) * | 1986-08-25 | 1995-04-26 | 株式会社日立製作所 | Manufacturing method of chemical resistant film |
-
1984
- 1984-10-08 JP JP21114884A patent/JPS6189708A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6189708A (en) | 1986-05-07 |
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