JP3163679B2 - Surface acoustic wave substrate - Google Patents
Surface acoustic wave substrateInfo
- Publication number
- JP3163679B2 JP3163679B2 JP24964491A JP24964491A JP3163679B2 JP 3163679 B2 JP3163679 B2 JP 3163679B2 JP 24964491 A JP24964491 A JP 24964491A JP 24964491 A JP24964491 A JP 24964491A JP 3163679 B2 JP3163679 B2 JP 3163679B2
- Authority
- JP
- Japan
- Prior art keywords
- film
- temperature coefficient
- acoustic wave
- surface acoustic
- substrate
- 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 - Fee Related
Links
- 239000000758 substrate Substances 0.000 title claims description 32
- 238000010897 surface acoustic wave method Methods 0.000 title claims description 22
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- 239000010408 film Substances 0.000 description 46
- 238000010586 diagram Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- RZVAJINKPMORJF-UHFFFAOYSA-N Acetaminophen Chemical compound CC(=O)NC1=CC=C(O)C=C1 RZVAJINKPMORJF-UHFFFAOYSA-N 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000005297 pyrex Substances 0.000 description 2
- 238000005546 reactive sputtering Methods 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- 229910013641 LiNbO 3 Inorganic materials 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000012888 cubic function Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
Landscapes
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Description
【０００１】[0001]
【産業上の利用分野】この発明は、弾性表面波基板に関
するもので、特に、零温度係数を得るための改良に関す
るものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface acoustic wave substrate, and more particularly to an improvement for obtaining a zero temperature coefficient.
【０００２】[0002]
【従来の技術】一般に、電子部品材料には、温度変化に
よる特性の変化、すなわち温度係数が小さいことが要求
される。弾性表面波基板においても例外ではない。弾性
表面波基板では、温度係数は、通常、遅延時間の温度変
化によって評価されている。2. Description of the Related Art In general, electronic component materials are required to have a characteristic change due to a temperature change, that is, a small temperature coefficient. The surface acoustic wave substrate is no exception. In the case of a surface acoustic wave substrate, the temperature coefficient is usually evaluated by the temperature change of the delay time.
【０００３】本発明者は、先に、石英ガラスからなる基
材上に圧電膜を形成した層構造基板、より具体的にはＺ
ｎＯ／パイレックスガラスおよびＴａ2 Ｏ5 ／石英ガラ
ス基板において、異符号の温度係数の組合せと温度係数
の膜厚依存性とから、層構造基板全体の温度係数を零に
近づける技術を提案している（特開昭５３−１１０３４
８号公報および特開昭６１−１９５０１３号公報）。The present inventor has previously proposed a layered substrate in which a piezoelectric film is formed on a substrate made of quartz glass, more specifically, a Z substrate.
In the case of nO / pyrex glass and Ta 2 O 5 / quartz glass substrates, a technique has been proposed in which the temperature coefficient of the entire layer structure substrate approaches zero due to the combination of different temperature coefficients and the dependence of the temperature coefficient on the thickness. (JP-A-53-11034
No. 8 and JP-A-61-195013).
【０００４】[0004]
【発明が解決しようとする課題】しかしながら、上述し
た従来技術では、１次温度係数にのみ注目しており、２
次温度係数については全く配慮されていない。弾性表面
波の遅延時間温度変化率と周波数温度変化率は、 Δｆ／ｆ＝−Δτ／τ ＝ａ（Ｔ−Ｔ0 ）＋ｂ（Ｔ−Ｔ0 ）2 で表わされる。ここで、Δｆは周波数変化量、ｆは周波
数、Δτは遅延時間変化量、τは遅延時間、Ｔは温度、
Ｔ0 は基準温度、ａは１次温度係数、ｂは２次温度係数
である。However, in the above-mentioned prior art, attention is paid only to the primary temperature coefficient,
No consideration is given to the secondary temperature coefficient. The delay time temperature change rate and the frequency temperature change rate of the surface acoustic wave are represented by Δf / f = −Δτ / τ = a (T−T 0 ) + b (T−T 0 ) 2 . Here, Δf is a frequency change amount, f is a frequency, Δτ is a delay time change amount, τ is a delay time, T is a temperature,
T 0 is a reference temperature, a is a primary temperature coefficient, and b is a secondary temperature coefficient.
【０００５】それゆえに、この発明の目的は、１次温度
係数および２次温度係数の双方ともに制御可能な弾性表
面波基板を提供しようとすることである。SUMMARY OF THE INVENTION It is an object of the present invention to provide a surface acoustic wave substrate capable of controlling both a first-order temperature coefficient and a second-order temperature coefficient.
【０００６】[0006]
【課題を解決するための手段】この発明にかかる弾性表
面波基板は、石英ガラスからなる基材と、この基材上に
形成される２層構造の圧電膜とを備え、圧電膜を構成す
る一方の層がＺｎＯからなり、他方の層がＴａ2 Ｏ5 か
らなることを特徴としている。A surface acoustic wave substrate according to the present invention comprises a substrate made of quartz glass, and a two-layer piezoelectric film formed on the substrate, forming a piezoelectric film. It is characterized in that one layer is made of ZnO and the other layer is made of Ta 2 O 5 .
【０００７】[0007]
【作用】この発明では、前述したいわゆる「温度補償
形」基板であるＺｎＯ／パイレックスガラス基板とＴａ
2 Ｏ5 ／石英ガラス基板とが、互いに異符号の２次温度
係数を有することに注目し、これらを組合せながら、Ｚ
ｎＯ層とＴａ2 Ｏ5 層との各々の厚みを調節することに
よって、１次温度係数および２次温度係数の双方を制御
できる。According to the present invention, a ZnO / Pyrex glass substrate which is a so-called "temperature compensation type" substrate and a Ta
Note that the 2 O 5 / quartz glass substrate has second-order temperature coefficients of opposite signs.
By adjusting the thickness of each of the nO layer and the Ta 2 O 5 layer, both the primary temperature coefficient and the secondary temperature coefficient can be controlled.
【０００８】[0008]
【発明の効果】このように、この発明によれば、弾性表
面波の周波数温度変化における１次温度係数だけでな
く、２次温度係数も制御することができる。それゆえ
に、このような１次温度係数および２次温度係数の双方
を制御することにより、１次および２次の双方について
零温度係数とされた弾性表面波基板を提供することがで
きる。As described above, according to the present invention, it is possible to control not only the first-order temperature coefficient but also the second-order temperature coefficient in the frequency temperature change of the surface acoustic wave. Therefore, by controlling both the first-order temperature coefficient and the second-order temperature coefficient, it is possible to provide a surface acoustic wave substrate having a zero temperature coefficient for both the first and second order.
【０００９】したがって、この発明による弾性表面波基
板を用いれば、たとえば通信機用弾性表面波共振子また
は弾性表面波フィルタなどの弾性表面波装置の信頼性を
高めることができる。Therefore, the use of the surface acoustic wave substrate according to the present invention can improve the reliability of a surface acoustic wave device such as a surface acoustic wave resonator for a communication device or a surface acoustic wave filter.
【００１０】[0010]
【実施例】図１には、この発明の一実施例による弾性表
面波基板１の一部が断面図で示されている。弾性表面波
基板１は、石英ガラス（ＳｉＯ2 ）からなる基材２と、
基材２上に形成される２層構造の圧電膜３とを備える。
圧電膜３を構成する一方の層は、ＺｎＯ膜４によって与
えられ、他方の層は、Ｔａ2 Ｏ5 膜５によって与えられ
る。この実施例では、基材２上に、ＺｎＯ膜４、Ｔａ2
Ｏ5 膜５の順に形成されたが、この順序は逆であっても
よい。FIG. 1 is a sectional view showing a part of a surface acoustic wave substrate 1 according to an embodiment of the present invention. The surface acoustic wave substrate 1 includes a substrate 2 made of quartz glass (SiO 2 ),
A piezoelectric film 3 having a two-layer structure formed on a base material 2.
One layer constituting the piezoelectric film 3 is provided by a ZnO film 4, and the other layer is provided by a Ta 2 O 5 film 5. In this embodiment, a ZnO film 4 and a Ta 2
Although the O 5 film 5 is formed in this order, the order may be reversed.
【００１１】図１に示した弾性表面波基板１の遅延時間
温度係数（ＴＣＤ）は、基材２、ＺｎＯ膜４およびＴａ
2 Ｏ5 膜５の各々の物理定数と温度係数とから計算でき
る。図２には、ＺｎＯ膜４の膜厚ｈ１をパラメータと
し、Ｔａ2 Ｏ5 膜５の膜厚ｈ２を変化させた場合の１次
温度係数が示されている。なお、図２においては、それ
ぞれの膜厚ｈ１およびｈ２は、ｈｋ１およびｈｋ２（ｋ
＝２π／λ）と基準化された膜厚で表わされている。The temperature coefficient of delay time (TCD) of the surface acoustic wave substrate 1 shown in FIG.
It can be calculated from each physical constant and temperature coefficient of the 2 O 5 film 5. Figure 2 is the thickness h1 of the ZnO film 4 as a parameter, the primary temperature coefficient is shown in the case of changing the thickness h2 of the Ta 2 O 5 film 5. In FIG. 2, the respective film thicknesses h1 and h2 are hk1 and hk2 (k
= 2π / λ) and the normalized film thickness.
【００１２】図２から、１次温度係数に関して、零温度
係数を与える膜厚の組合せが多数存在することがわか
る。FIG. 2 shows that there are many combinations of film thicknesses that give a zero temperature coefficient with respect to the primary temperature coefficient.
【００１３】図３は、図２に示した結果から導き出され
る、１次温度係数ａに関して零温度係数を与える膜厚の
組合せを示している。FIG. 3 shows combinations of film thicknesses that give a zero temperature coefficient with respect to the primary temperature coefficient a, which are derived from the results shown in FIG.
【００１４】図３に示した曲線上に位置する膜厚の組合
せに従って、さらに２次温度係数ｂに関しても零温度係
数を与え得る膜厚の組合せを探究すべく、以下の実験を
行なった。The following experiment was conducted in order to find a combination of film thicknesses capable of providing a zero temperature coefficient with respect to the secondary temperature coefficient b in accordance with the combination of film thicknesses located on the curve shown in FIG.
【００１５】ＺｎＯ膜４およびＴａ2 Ｏ5 膜５は、それ
ぞれ、ターゲットにＺｎＯおよびＴａを用い、反応性ス
パッタリング法で作製した。ＺｎＯ膜４は、ｃ軸配向し
たものを、Ｔａ2 Ｏ5 膜５は、作製上の制約から、アモ
ルファス膜を採用した。しかし、温度特性に関しては、
アモルファス膜は、ｘ軸配向の膜と差異はないように推
測される。周波数温度変化の測定は、標準試料（１２８
°ＹＸ・ＬｉＮｂＯ3 ）の発振器を構成し、温度の校正
を行ない、干渉による零点法で行なった。The ZnO film 4 and the Ta 2 O 5 film 5 were prepared by reactive sputtering using ZnO and Ta as targets. The ZnO film 4 was c-axis oriented, and the Ta 2 O 5 film 5 was an amorphous film due to manufacturing restrictions. However, regarding the temperature characteristics,
It is assumed that the amorphous film is not different from the x-axis oriented film. The measurement of the frequency temperature change is performed using a standard sample (128
(YX.LiNbO 3 ) was constructed, the temperature was calibrated, and the zero point method based on interference was performed.
【００１６】図３において、「○」印は、上述の実験に
より得られたいくつかの試料の膜厚の組合せに相当する
点を示している。「○」印で示された各試料について、
２次温度係数ｂを求めると、図３に示す数値のとおりと
なった。すなわち、ｈｋ１＝０，ｈｋ２＝１．７８にお
いて、ｂ＞０、また、ｈｋ１＝１．８５，ｈｋ２＝０に
おいて、ｂ＜０となることに注目すると、図３の１次温
度係数ａが零になる曲線上において、２次温度係数ｂが
正から負へ変化し、ｂ＝０を与える膜厚の組合せが必ず
存在することがわかる。加えて、ｈｋ１＝０．８８，ｈ
ｋ２＝０．６６において、２次温度係数ｂがほぼ零の値
を示している。このことから、ｈｋ１＝０．８８，ｈｋ
２＝０．６６の膜厚の組合せ付近で、２次温度係数ｂが
零になることが推測できる。In FIG. 3, marks “○” indicate points corresponding to combinations of the film thicknesses of some samples obtained by the above-described experiments. For each sample marked with a “○”,
When the secondary temperature coefficient b was obtained, the values were as shown in FIG. That is, when it is noted that b> 0 at hk1 = 0 and hk2 = 1.78 and b <0 at hk1 = 1.85 and hk2 = 0, the primary temperature coefficient a in FIG. It can be seen that on the curve, the secondary temperature coefficient b changes from positive to negative, and there is always a combination of film thicknesses that gives b = 0. In addition, hk1 = 0.88, h
At k2 = 0.66, the secondary temperature coefficient b shows a value of almost zero. From this, hk1 = 0.88, hk
It can be estimated that the secondary temperature coefficient b becomes zero near the combination of the film thicknesses of 2 = 0.66.
【００１７】次に、基準化膜厚ｈｋ１＝０．８８のＺｎ
Ｏ膜４の上にＴａ2Ｏ5 膜５を種々の厚みで形成した試
料を作製し、その１次温度係数（ＴＣＤ）を求めたとこ
ろ、図４に示すような結果が得られた。図４において、
「○」印で示した実験値にばらつきが生じているのは、
Ｔａ2 Ｏ5 を５回に分けて形成し、それぞれの膜厚で周
波数を変えて測定を行なったため、および、温度を変化
させたことによる膜の変化が生じたためであると考えら
れる。図４に示した結果は、前述した図２に示した計算
結果と符合している。図４から、ｈｋ１＝０．８８，ｈ
ｋ２＝０．６６において、１次温度係数が零となること
がわかる。Next, Zn having a standardized film thickness hk1 = 0.88
Samples having various thicknesses of the Ta 2 O 5 film 5 formed on the O film 4 were prepared, and their primary temperature coefficients (TCD) were obtained. The results shown in FIG. 4 were obtained. In FIG.
Variations in the experimental values indicated by the “」 ”marks
This is presumably because Ta 2 O 5 was formed five times and the frequency was changed for each film thickness, and the film was changed by changing the temperature. The result shown in FIG. 4 matches the calculation result shown in FIG. 2 described above. From FIG. 4, hk1 = 0.88, h
It can be seen that the primary temperature coefficient becomes zero at k2 = 0.66.
【００１８】上述したｈｋ１＝０．８８，ｈｋ２＝０．
６６の試料の温度変化による周波数の変化率が図５に示
されている。この試料は、図３に示すように、ｂがほぼ
零であり、その周波数変化率は、測定誤差（±３ｐｐ
ｍ）を考慮しても３次関数に近似できる。The above hk1 = 0.88, hk2 = 0.
FIG. 5 shows the rate of change of the frequency due to the temperature change of the 66 samples. In this sample, as shown in FIG. 3, b is almost zero, and the frequency change rate is the measurement error (± 3 pp).
m) can be approximated to a cubic function.
【００１９】このように、図１に示した２層構造の圧電
膜３を有する弾性表面波基板１によれば、１次温度係数
と２次温度係数との双方が制御可能であり、結果として
３次特性を示す高安定な弾性表面波基板を実現できる。As described above, according to the surface acoustic wave substrate 1 having the two-layer piezoelectric film 3 shown in FIG. 1, both the primary temperature coefficient and the secondary temperature coefficient can be controlled. A highly stable surface acoustic wave substrate exhibiting tertiary characteristics can be realized.
【００２０】なお、上述した実験例では、ＺｎＯ膜４お
よびＴａ2 Ｏ5 膜５の形成を、反応性スパッタリング法
で行なったが、その他、ＣＶＤ法などの薄膜形成方法に
よって行なってもよい。In the experimental example described above, the ZnO film 4 and the Ta 2 O 5 film 5 are formed by a reactive sputtering method, but may be formed by a thin film forming method such as a CVD method.
【図１】この発明の一実施例による弾性表面波基板１の
一部を拡大して示す断面図である。FIG. 1 is an enlarged sectional view showing a part of a surface acoustic wave substrate 1 according to an embodiment of the present invention.
【図２】図１に示した弾性表面波基板１において、Ｚｎ
Ｏ膜４の基準化膜厚ｈｋ１をパラメータとし、Ｔａ2 Ｏ
5 膜５の基準化膜厚ｈｋ２を変化させた場合の１次温度
係数（ＴＣＤ）の計算結果を示す図である。FIG. 2 shows a surface acoustic wave substrate 1 shown in FIG.
Using the normalized thickness hk1 of the O film 4 as a parameter, Ta 2 O
5 is a diagram showing a calculation result of a primary temperature coefficient (TCD) when the standardized film thickness hk2 of the five films 5 is changed. FIG.
【図３】図２に示した結果から導き出される、１次温度
係数ａに関して零温度係数を与える膜厚の組合せを示す
図であり、併せて、実験により得られたいくつかの試料
の２次温度係数ｂの数値も示している。FIG. 3 is a diagram showing combinations of film thicknesses giving a zero temperature coefficient with respect to a primary temperature coefficient a, which are derived from the results shown in FIG. 2; The numerical value of the temperature coefficient b is also shown.
【図４】基準化膜厚ｈｋ１＝０．８８のＺｎＯ膜４の上
にＴａ2 Ｏ5 膜５を種々の厚みで形成した試料の１次温
度係数（ＴＣＤ）を示す図である。FIG. 4 is a diagram showing first order temperature coefficients (TCD) of samples in which Ta 2 O 5 films 5 are formed at various thicknesses on a ZnO film 4 having a standardized film thickness hk1 = 0.88.
【図５】ｈｋ１＝０．８８，ｈｋ２＝０．６６の試料の
温度変化による周波数の変化率を示す図である。FIG. 5 is a diagram showing a rate of change in frequency due to a temperature change of a sample when hk1 = 0.88 and hk2 = 0.66.
１ 弾性表面波基板 ２ 基材 ３ 圧電膜 ４ ＺｎＯ膜 ５ Ｔａ2 Ｏ5 膜1 SAW substrate 2 substrate 3 piezoelectric film 4 ZnO film 5 Ta 2 O 5 film
フロントページの続き (56)参考文献 特開 昭54−66792（ＪＰ，Ａ) Ｙ．ＮＡＫＡＧＡＷＡ；“ＣＯＮＴＲ ＯＬ ＯＦ ＳＥＣＯＮＤ ＯＲＤＥＲ ＴＥＭＰＥＲＡＴＵＲＥ ＣＥＦＦＩ ＣＩＥＮＴ ＯＦ ＳＡＷ ＰＲＯＰＡ ＧＡＴＩＮＧ ＩＮ ＴＷＯ ＴＨＩＮ ＦＩＬＭ ＬＡＹＥＲＳ”1993 ＩＥ ＥＥ ＵＬＴＲＡＳＯＮＩＣＳ ＳＹＭ ＰＯＳＩＵＭ，ＶＯＬ１ Ｐ．287−290 中川恭彦 他；“層構造弾性表面波基 板の２次温度係数制御”電子情報通信学 会技術研究報告，Ｖｏｌ．91（ＵＳ91− 51），Ｎｏ．274 ｐ．29−36 (58)調査した分野(Int.Cl.7，ＤＢ名) H03H 9/25 Continuation of front page (56) References JP-A-54-66792 (JP, A) NAGAGAWA; "CONTROL OF SECOND ORDER TEMPERATURE CEFFI CIENT OF SAW PROPA GATING IN TWO THIN FILM LAYERS" 1993 IE ULTRASONICS Symposium. 287-290 Yasuhiko Nakagawa et al .; "Secondary Temperature Coefficient Control of Layered Surface Acoustic Wave Substrate" IEICE Technical Report, Vol. 91 (US91-51), no. 274 p. 29-36 (58) Field surveyed (Int. Cl. 7 , DB name) H03H 9/25
Claims (1)
の層がＴａ2 Ｏ5 からなる、 弾性表面波基板。1. A piezoelectric device comprising: a substrate made of quartz glass; and a piezoelectric film having a two-layer structure formed on the substrate. One of the layers constituting the piezoelectric film is made of ZnO, and the other layer is made of Ta. A surface acoustic wave substrate made of 2 O 5 .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24964491A JP3163679B2 (en) | 1991-09-27 | 1991-09-27 | Surface acoustic wave substrate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24964491A JP3163679B2 (en) | 1991-09-27 | 1991-09-27 | Surface acoustic wave substrate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0590889A JPH0590889A (en) | 1993-04-09 |
| JP3163679B2 true JP3163679B2 (en) | 2001-05-08 |
Family
ID=17196091
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24964491A Expired - Fee Related JP3163679B2 (en) | 1991-09-27 | 1991-09-27 | Surface acoustic wave substrate |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3163679B2 (en) |
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| JP3717034B2 (en) * | 1998-11-10 | 2005-11-16 | 株式会社村田製作所 | Surface acoustic wave device |
| JP4385607B2 (en) * | 2003-01-29 | 2009-12-16 | セイコーエプソン株式会社 | Surface acoustic wave device, frequency filter, oscillator, electronic circuit and electronic equipment |
| CN109988997B (en) * | 2019-03-21 | 2020-12-08 | 淮阴工学院 | Thermal film and its preparation method and application |
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1991
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Non-Patent Citations (2)
| Title |
|---|
| Ｙ．ＮＡＫＡＧＡＷＡ；"ＣＯＮＴＲＯＬ ＯＦ ＳＥＣＯＮＤ ＯＲＤＥＲ ＴＥＭＰＥＲＡＴＵＲＥ ＣＥＦＦＩＣＩＥＮＴ ＯＦ ＳＡＷ ＰＲＯＰＡＧＡＴＩＮＧ ＩＮ ＴＷＯ ＴＨＩＮ ＦＩＬＭ ＬＡＹＥＲＳ"１９９３ ＩＥＥＥ ＵＬＴＲＡＳＯＮＩＣＳ ＳＹＭＰＯＳＩＵＭ，ＶＯＬ１ Ｐ．２８７−２９０ |
| 中川恭彦 他；"層構造弾性表面波基板の２次温度係数制御"電子情報通信学会技術研究報告，Ｖｏｌ．９１（ＵＳ９１−５１），Ｎｏ．２７４ ｐ．２９−３６ |
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| Publication number | Publication date |
|---|---|
| JPH0590889A (en) | 1993-04-09 |
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