JP2001196895A - Surface acoustic wave device - Google Patents
Surface acoustic wave deviceInfo
- Publication number
- JP2001196895A JP2001196895A JP2000002571A JP2000002571A JP2001196895A JP 2001196895 A JP2001196895 A JP 2001196895A JP 2000002571 A JP2000002571 A JP 2000002571A JP 2000002571 A JP2000002571 A JP 2000002571A JP 2001196895 A JP2001196895 A JP 2001196895A
- Authority
- JP
- Japan
- Prior art keywords
- acoustic wave
- surface acoustic
- zno
- wave device
- value
- 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.)
- Withdrawn
Links
- 238000010897 surface acoustic wave method Methods 0.000 title claims abstract description 36
- 239000010410 layer Substances 0.000 claims abstract description 38
- 239000000758 substrate Substances 0.000 claims abstract description 28
- 229910004298 SiO 2 Inorganic materials 0.000 claims abstract description 21
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 15
- 239000011241 protective layer Substances 0.000 claims abstract description 13
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims abstract description 9
- 229910052709 silver Inorganic materials 0.000 claims abstract description 7
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 82
- 239000011787 zinc oxide Substances 0.000 claims description 41
- 229910018068 Li 2 O Inorganic materials 0.000 claims description 9
- 235000012239 silicon dioxide Nutrition 0.000 claims description 9
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 7
- 229910052710 silicon Inorganic materials 0.000 claims description 7
- 239000010703 silicon Substances 0.000 claims description 7
- 229910052802 copper Inorganic materials 0.000 claims description 5
- 239000000377 silicon dioxide Substances 0.000 claims description 5
- 239000011701 zinc Substances 0.000 claims description 4
- 238000000034 method Methods 0.000 claims description 2
- 239000010409 thin film Substances 0.000 abstract description 8
- 238000000151 deposition Methods 0.000 abstract description 7
- 239000010453 quartz Substances 0.000 abstract description 5
- 238000004891 communication Methods 0.000 abstract description 4
- 229910052744 lithium Inorganic materials 0.000 abstract description 4
- 239000013078 crystal Substances 0.000 abstract description 2
- 238000003780 insertion Methods 0.000 abstract description 2
- 230000037431 insertion Effects 0.000 abstract description 2
- 238000010030 laminating Methods 0.000 abstract description 2
- 238000009413 insulation Methods 0.000 abstract 1
- 239000010408 film Substances 0.000 description 14
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 8
- 229910052760 oxygen Inorganic materials 0.000 description 8
- 239000001301 oxygen Substances 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 239000000463 material Substances 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 238000000608 laser ablation Methods 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000010924 continuous production Methods 0.000 description 2
- 238000001312 dry etching Methods 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000000059 patterning Methods 0.000 description 2
- 150000001768 cations Chemical class 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000012776 electronic material Substances 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000010295 mobile communication Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
Landscapes
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
(57)【要約】
【課題】 温度安定性を目指した表面弾性波素子である
水晶上のZnO薄膜の場合、他の電子デバイスとの集積
化が困難であり、ZnOの絶縁性が低下しやすく、水晶
の負のTCF値の絶対値が小さいのでZnOの膜厚を厚
くできず、素子全体のk2が小さくなる、といった欠点
があった。
【解決手段】 (100)Si基板11上に、Li,C
u、Agの少なくとも一つを添加した(001)配向Z
nO圧電体層13を積層することにより、圧電性が向上
しk2の値を増大させることができ、さらにその上にL
i2O、MgO、Al2O3のの少なくとも一つを含み負
の中心周波数温度係数(TCF)値を有するSiO2保
護層16を堆積することにより、k2値を減少させるこ
となく素子全体のTCF値を零にすることができ、挿入
損失が小さく温度安定性に優れた高周波フィルタ、発振
器などの通信デバイスを実現することができる。
PROBLEM TO BE SOLVED: To provide a ZnO thin film on quartz, which is a surface acoustic wave device aiming at temperature stability, because it is difficult to integrate with other electronic devices, and the insulation of ZnO is apt to decrease. Further, since the absolute value of the negative TCF value of the crystal is small, the thickness of ZnO cannot be increased, and the k 2 of the entire device is reduced. SOLUTION: On a (100) Si substrate 11, Li, C
(001) orientation Z to which at least one of u and Ag is added
By laminating the nO piezoelectric layer 13, the piezoelectricity can be improved and the value of k 2 can be increased.
By depositing an SiO 2 protective layer 16 having at least one of i 2 O, MgO and Al 2 O 3 and having a negative center frequency temperature coefficient (TCF) value, the entire device can be manufactured without reducing the k 2 value. Can be reduced to zero, and a communication device such as a high-frequency filter or an oscillator having low insertion loss and excellent temperature stability can be realized.
Description
【0001】[0001]
【発明の属する技術分野】本発明は、情報通信分野に用
いられる表面弾性波素子に関し、特に圧電薄膜を用いた
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 device used in the field of information communication, and more particularly to a surface acoustic wave device using a piezoelectric thin film.
【0002】[0002]
【従来の技術】携帯電話などの移動体通信を中心とした
通信分野の著しい発展に伴い、表面弾性波素子の需要が
急速に拡大している。表面弾性波素子の開発の方向とし
ては、小型化、高効率化、高周波化の方向にあり、その
ためには、より大きな電気機械結合係数(以下k2)、
より安定な温度特性、より大きな表面弾性波伝播速度、
が必要となる。表面弾性波素子は、フィルタ、共振器等
に用いられるが、例えば発振器として用いる場合は、そ
の中心周波数温度係数(TCF)がなるべく零に近くな
るような温度特性が望ましい。表面弾性波素子は、従
来、主として圧電体の単結晶上にインターディジタル型
電極(Inter−Digital Transduc
er、以下IDT)を形成した構造が用いられてきた
が、温度特性の安定が必要なIFフィルタや発振器の場
合には、TCFが零に近い水晶が圧電体基板として用い
られてきた。2. Description of the Related Art The demand for surface acoustic wave devices has been rapidly expanding with the remarkable development of the communication field centering on mobile communication such as mobile phones. The direction of development of surface acoustic wave devices is in the direction of miniaturization, high efficiency, and high frequency, and for that purpose, a larger electromechanical coupling coefficient (hereinafter k 2 ),
More stable temperature characteristics, larger surface acoustic wave propagation velocity,
Is required. The surface acoustic wave device is used for a filter, a resonator, or the like. For example, when the surface acoustic wave device is used as an oscillator, it is desirable that the temperature characteristic is such that its center frequency temperature coefficient (TCF) is as close to zero as possible. Conventionally, a surface acoustic wave device is mainly composed of an inter-digital electrode (Inter-Digital Transducc) on a piezoelectric single crystal.
er (hereinafter, IDT) has been used. However, in the case of an IF filter or an oscillator that requires stable temperature characteristics, quartz having a TCF close to zero has been used as a piezoelectric substrate.
【0003】一方、酸化亜鉛(以下ZnO)のような温
度特性に劣る圧電材料の場合には、例えば「表面波デバ
イスとその応用」電子材料工業会編 1978年発行 p
p106〜108 に記載されているように、TCFの
符号が異なる材料、例えば二酸化珪素(以下SiO2)
との積層によって温度特性を改善することが試みられて
きた。Jpn.J.Appl.Phys.Vol.36
(1997)pp.3076−3080や特開平9−1
30192に記載されているように、正のTCF値を有
するカット角および伝播方向の水晶基板上に負のTCF
値を有するZnO圧電膜を形成し、その膜厚を最適化す
ることによってTCFを零近傍に調整することが試みら
れている。この場合、それぞれの層の膜厚を最適化する
ことによって、温度特性のみならず、k2、表面波の伝
播速度をも改善することが可能となる。On the other hand, in the case of a piezoelectric material having inferior temperature characteristics such as zinc oxide (hereinafter referred to as ZnO), for example, “Surface Wave Devices and Their Applications”, edited by Electronic Materials Industry Association, published in 1978, p.
As described on pages 106 to 108, materials having different signs of TCF, for example, silicon dioxide (hereinafter, SiO 2 )
Attempts have been made to improve the temperature characteristics by laminating them. Jpn. J. Appl. Phys. Vol. 36
(1997) p. 3076-3080 and JP-A-9-19-1
As described in US Pat. No. 30192, a negative TCF on a quartz substrate with a cut angle and propagation direction having a positive TCF value.
Attempts have been made to adjust the TCF to near zero by forming a ZnO piezoelectric film having a certain value and optimizing the film thickness. In this case, by optimizing the film thickness of each layer, it is possible to improve not only the temperature characteristics but also the k 2 and the propagation speed of the surface wave.
【0004】[0004]
【発明が解決しようとする課題】しかし、従来の水晶上
のZnO薄膜を用いた表面弾性波素子には、以下のよう
な問題点がある。However, the conventional surface acoustic wave device using a ZnO thin film on quartz has the following problems.
【0005】まず、水晶基板を使用しなくてはならない
ため、他の電子デバイスと集積化することが困難であっ
た。従って、シリコン(以下Si)基板上に直接堆積す
る構造が実現できれば、製造コストの低減も含めて大変
有用である。またSiは、表面弾性波の伝播速度が50
00m/s程度と大きいことも、高周波化にとって有用
である。First, since a quartz substrate must be used, it has been difficult to integrate it with other electronic devices. Therefore, if a structure in which the film is directly deposited on a silicon (hereinafter, Si) substrate can be realized, it is very useful including reduction in manufacturing cost. Si has a surface acoustic wave propagation velocity of 50
A large value of about 00 m / s is also useful for increasing the frequency.
【0006】次に、ZnOは一般にn型半導体の性質を
示す材料であるため、低酸素雰囲気下での製膜プロセス
によって酸素欠陥が生じると、導電性が出現してリーク
電流や圧電定数の低下などの問題が生じやすかった。従
って、ZnOの絶縁性を確保するため、Znより価数の
小さな金属、すなわち1価の陽イオンになりやすい金属
を添加することが望ましい。Next, since ZnO is a material generally exhibiting the properties of an n-type semiconductor, when oxygen defects are generated by a film forming process in a low oxygen atmosphere, conductivity appears to cause a decrease in leak current and piezoelectric constant. Problems such as were easy to occur. Therefore, in order to secure the insulating property of ZnO, it is desirable to add a metal having a lower valence than Zn, that is, a metal that easily becomes a monovalent cation.
【0007】一方、正のTCFを有するSiO2につい
ては、ZnOの負のTCFを相殺するためにはその膜厚
をある程度厚くする必要があるが、その場合SiO2の
小さなk2の影響で、素子全体のk2が小さくなってしま
うといった欠点があった。従って、SiO2よりTCF
の大きな材料を選択することが望ましく、このような材
料としては、負の熱膨張係数を有するものが有望であ
る。On the other hand, the SiO 2 having a positive TCF is to offset the negative TCF of ZnO it is necessary to increase the film thickness to some extent, in which case the influence of small k 2 of SiO 2, There is a drawback that k 2 of the entire device is reduced. Therefore, TCF is better than SiO 2
It is desirable to select a material having a large thermal expansion coefficient, and a material having a negative coefficient of thermal expansion is promising.
【0008】本発明は以上述べた問題点を解決するもの
であり、温度特性に優れかつk2が高く高周波化に対応
できる薄膜を用いた表面弾性波素子を提供するものであ
る。The present invention solves the above-mentioned problems, and provides a surface acoustic wave device using a thin film which is excellent in temperature characteristics and has a high k 2 and can cope with a higher frequency.
【0009】[0009]
【課題を解決するための手段】請求項1記載の表面弾性
波素子は、(100)Si基板と、前記Si基板上のS
iO2からなるバッファ層と、前記SiO2バッファ層上
のZnOからなる圧電体層とからなり、前記ZnO圧電
体層の直下または直上にIDTを形成することを特徴と
する。According to a first aspect of the present invention, there is provided a surface acoustic wave device comprising: a (100) Si substrate;
It is characterized by comprising a buffer layer made of iO 2 and a piezoelectric layer made of ZnO on the SiO 2 buffer layer, wherein an IDT is formed immediately below or directly above the ZnO piezoelectric layer.
【0010】上記構成によれば、Si基板上に直接Zn
O圧電体を堆積する構造が実現でき、製造コストの低減
や他の電子デバイスの集積化にとって有利であるという
効果を有する。According to the above configuration, Zn is directly formed on the Si substrate.
A structure in which an O piezoelectric material is deposited can be realized, which is advantageous in reducing manufacturing costs and integrating other electronic devices.
【0011】請求項2記載の表面弾性波素子は、ZnO
圧電体層において、Znの一部をLi、Cu、Agの少
なくとも一つで置換した組成を有することを特徴とす
る。According to a second aspect of the present invention, there is provided a surface acoustic wave device comprising ZnO
The piezoelectric layer has a composition in which Zn is partially replaced with at least one of Li, Cu, and Ag.
【0012】上記構成によれば、ZnO圧電体層のリー
ク電流や圧電定数の低下などの問題を改善するという効
果を有する。According to the above configuration, there is an effect that problems such as a leak current of the ZnO piezoelectric layer and a decrease in the piezoelectric constant are improved.
【0013】請求項3記載の表面弾性波素子は、ZnO
圧電体層において、c軸が前記シリコン基板に垂直に配
向し、かつa軸が前記シリコン基板に平行な面内で配向
したエピタキシャル膜であることを特徴とする。According to a third aspect of the present invention, there is provided a surface acoustic wave device comprising ZnO
In the piezoelectric layer, the c-axis is oriented perpendicular to the silicon substrate, and the a-axis is an epitaxial film oriented in a plane parallel to the silicon substrate.
【0014】上記構成によれば、平坦で緻密なエピタキ
シャル膜が得られるので、リーキー波伝播に伴う損失を
低減させるという効果を有する。According to the above configuration, since a flat and dense epitaxial film can be obtained, there is an effect that a loss caused by leaky wave propagation is reduced.
【0015】請求項4記載の表面弾性波素子は、ZnO
圧電体層の上に、SiO2からなる保護層を有すること
を特徴とする。According to a fourth aspect of the present invention, there is provided a surface acoustic wave device comprising ZnO
It is characterized by having a protective layer made of SiO 2 on the piezoelectric layer.
【0016】上記構成によれば、正のTCFを有するS
iO2層がZnO層の負のTCFを相殺して素子全体の
TCFを零にすることができ、温度安定性が改善される
という効果を有する。According to the above configuration, S having a positive TCF
The iO 2 layer can cancel the negative TCF of the ZnO layer to make the TCF of the entire device zero, thereby improving temperature stability.
【0017】請求項5記載の表面弾性波素子は、SiO
2保護層において、SiO2の他、Li2O、MgO、A
l2O3の少なくとも一つを含むことを特徴とする。According to a fifth aspect of the present invention, there is provided a surface acoustic wave device comprising:
2 In the protective layer, besides SiO 2 , Li 2 O, MgO, A
It is characterized by containing at least one of l 2 O 3 .
【0018】上記構成によれば、SiO2層の正のTC
F値を増大させることができるので、SiO2保護層の
厚みを低減でき、素子全体のk2が改善されるという効
果を有する。According to the above configuration, the positive TC of the SiO 2 layer
Since the F value can be increased, the thickness of the SiO 2 protective layer can be reduced, and k 2 of the entire device can be improved.
【0019】[0019]
【発明の実施の形態】以下、本発明を実施例にしたがっ
て詳細に説明する。DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments.
【0020】(実施例1)図1は本発明の表面弾性波素
子の第1の実施例を示す図である。(Embodiment 1) FIG. 1 is a view showing a first embodiment of a surface acoustic wave device according to the present invention.
【0021】Liを3mol%添加したZnOターゲッ
トを用いたレーザアブレーションにより、基板温度60
0℃、酸素分圧3×10-3Torrの条件で、Si基板
1上にZnO圧電体層3を2μm堆積した。このとき、
Si基板1とZnO圧電体層3の間には、熱酸化による
SiO2酸化膜層2が形成される。ただし、基板温度、
酸素分圧は、これに限るものではなく、Li添加量もこ
れに限るものではない。The substrate temperature was adjusted to 60 by laser ablation using a ZnO target to which 3 mol% of Li was added.
At 0 ° C. and an oxygen partial pressure of 3 × 10 −3 Torr, a 2 μm ZnO piezoelectric layer 3 was deposited on the Si substrate 1. At this time,
The SiO 2 oxide film layer 2 is formed between the Si substrate 1 and the ZnO piezoelectric layer 3 by thermal oxidation. However, substrate temperature,
The oxygen partial pressure is not limited to this, and the amount of Li added is not limited to this.
【0022】次に、金属アルミニウムを蒸着後、レジス
ト塗布、露光、ドライエッチング、レジスト除去による
パターニングの連続プロセスを行い、ZnO圧電体層3
上にIDT電極4、5を形成した。Next, after depositing metal aluminum, a continuous process of resist coating, exposure, dry etching, and patterning by removing the resist is performed to form a ZnO piezoelectric layer 3.
IDT electrodes 4 and 5 were formed thereon.
【0023】得られた表面弾性波素子は、擬立方晶指数
表示した場合、膜面に垂直方向に(001)ZnO/
(100)Si、面内で[100]ZnO//[10
0]Siの配向膜であった。得られた表面弾性波素子に
ついて、IDT電極4、5の間での表面弾性波の遅延時
間Vopenから求めた音速は4000m/sであった。I
DT電極4、5の間を金属薄膜で覆った場合の表面弾性
波の遅延時間Vshortとの差から求めると、k2は0.0
1となった。Liを添加しないZnOターゲットを用い
た場合に、音速が4000m/s、k2が0.001で
あることから、Liを添加して圧電性が向上したことが
明らかである。When the obtained surface acoustic wave device is expressed in pseudo cubic index, the (001) ZnO /
(100) Si, [100] ZnO // [10
0] It was an oriented film of Si. With respect to the obtained surface acoustic wave device, the sound velocity determined from the delay time V open of the surface acoustic wave between the IDT electrodes 4 and 5 was 4000 m / s. I
When calculated from the difference from the delay time V short of the surface acoustic wave when the space between the DT electrodes 4 and 5 is covered with a metal thin film, k 2 is 0.0
It became 1. When using a ZnO target without added Li, since the sound velocity is 4000 m / s, k 2 is 0.001, it is clear that improved piezoelectric properties by addition of Li.
【0024】また、Liの代わりにCuまたはAgを添
加したZnOを圧電体層に用いた場合も同様な効果が得
られた。なお、IDT電極を圧電体層の下に形成した場
合も同様な効果が得られた。上述のように、Li、C
u、Agのいずれかを添加したZnOターゲットを用い
て(100)Si基板上に(001)配向ZnO圧電薄
膜を堆積することにより、k2を向上させることが可能
となる。Similar effects were obtained when ZnO to which Cu or Ag was added instead of Li was used for the piezoelectric layer. The same effect was obtained when the IDT electrode was formed under the piezoelectric layer. As described above, Li, C
By depositing a (001) oriented ZnO piezoelectric thin film on a (100) Si substrate using a ZnO target to which either u or Ag is added, k 2 can be improved.
【0025】(実施例2)図2は本発明の表面弾性波素
子の第2の実施例を示す図である。(Embodiment 2) FIG. 2 is a view showing a surface acoustic wave device according to a second embodiment of the present invention.
【0026】Liを3mol%添加したZnOターゲッ
トを用いたレーザアブレーションにより、基板温度60
0℃、酸素分圧3×10-3Torrの条件で、Si基板
11上にZnO圧電体層13を2μm堆積した。このと
き、Si基板11とZnO圧電体層13の間には、熱酸
化によるSiO2酸化膜層12が形成される。ただし、
基板温度、酸素分圧は、これに限るものではなく、Li
添加量もこれに限るものではない。The substrate temperature was adjusted to 60 by laser ablation using a ZnO target to which 3 mol% of Li was added.
Under a condition of 0 ° C. and an oxygen partial pressure of 3 × 10 −3 Torr, a 2 μm ZnO piezoelectric layer 13 was deposited on the Si substrate 11. At this time, the SiO 2 oxide film layer 12 is formed between the Si substrate 11 and the ZnO piezoelectric layer 13 by thermal oxidation. However,
The substrate temperature and the oxygen partial pressure are not limited to those described above.
The amount of addition is not limited to this.
【0027】次に、金属アルミニウムを蒸着後、レジス
ト塗布、露光、ドライエッチング、レジスト除去による
パターニングの連続プロセスを行い、ZnO圧電層13
上にIDT電極14、15を形成した。Next, after vapor deposition of metal aluminum, a continuous process of resist coating, exposure, dry etching, and patterning by resist removal is performed to obtain a ZnO piezoelectric layer 13.
IDT electrodes 14 and 15 were formed thereon.
【0028】最後に、Li2O・Al2O3・4SiO2タ
ーゲットを用いたレーザアブレーションにより、基板温
度25℃、酸素分圧3mTorrの条件で、SiO2保
護層16を2μm堆積した。ただし、基板温度、酸素分
圧は、これに限るものではない。Finally, a 2 μm SiO 2 protective layer 16 was deposited by laser ablation using a Li 2 O.Al 2 O 3 .4SiO 2 target under the conditions of a substrate temperature of 25 ° C. and an oxygen partial pressure of 3 mTorr. However, the substrate temperature and the oxygen partial pressure are not limited to these.
【0029】得られた表面弾性波素子は、擬立方晶指数
表示した場合、膜面に垂直方向に(001)ZnO/
(100)Si、面内で[100]ZnO//[10
0]Siの配向膜であった。またSiO2保護層はアモ
ルファスであった。When the obtained surface acoustic wave device is represented by a pseudo cubic index, the (001) ZnO /
(100) Si, [100] ZnO // [10
0] It was an oriented film of Si. Further, the SiO 2 protective layer was amorphous.
【0030】得られた表面弾性波素子について、IDT
電極14、15の間での表面弾性波の遅延時間Vopenか
ら求めた音速は4000m/sであった。IDT電極1
4、15の間を金属薄膜で覆った場合の表面弾性波の遅
延時間Vshortとの差から求めると、k2は0.01とな
った。TCFは25℃で−1ppm/℃であった。これ
は、Li2OまたはAl2O3を添加しないSiO2ターゲ
ットを用いた場合に比べ、音速4000m/s、k2=
0.01は同じであるが、TCFは25℃で−10pp
m/℃という値に比べてはるかに小さくなった。For the obtained surface acoustic wave device, IDT
The speed of sound obtained from the delay time V open of the surface acoustic wave between the electrodes 14 and 15 was 4000 m / s. IDT electrode 1
When calculated from the difference from the delay time V short of the surface acoustic wave when the area between 4 and 15 was covered with a metal thin film, k 2 was 0.01. TCF was -1 ppm / ° C at 25 ° C. This is 4000 m / s in sound velocity and k 2 = as compared with the case of using a SiO 2 target to which Li 2 O or Al 2 O 3 is not added.
0.01 is the same, but the TCF is −10 pp at 25 ° C.
It was much smaller than the value of m / ° C.
【0031】また、Liの代わりにCuまたはAgを添
加したZnOを圧電体層に用いた場合も同様な効果が得
られた。さらに、Li2O・Al2O3・4SiO2の代わ
りにLi2O、MgO、Al2O3のいずれかを含んだS
iO2を保護層に用いた場合も、同様な効果が得られ
た。なお、IDT電極を圧電体層の下に形成した場合も
同様な効果が得られた。Similar effects were obtained when ZnO to which Cu or Ag was added instead of Li was used for the piezoelectric layer. Further, instead of Li 2 O of Li 2 O · Al 2 O 3 · 4SiO 2, MgO, containing one of Al 2 O 3 S
Similar effects were obtained when iO 2 was used for the protective layer. The same effect was obtained when the IDT electrode was formed under the piezoelectric layer.
【0032】上述のように、(100)Si基板上に、
Li、Cu、Agのいずれかを添加したZnO圧電薄膜
を堆積し、さらにLi2O、MgO、Al2O3を含んだ
SiO2保護層を堆積することにより、温度特性を向上
させることが可能となる。As described above, on a (100) Si substrate,
Temperature characteristics can be improved by depositing a ZnO piezoelectric thin film to which any of Li, Cu, and Ag are added, and further depositing a SiO 2 protective layer containing Li 2 O, MgO, and Al 2 O 3. Becomes
【0033】[0033]
【発明の効果】以上述べたように、本発明の表面弾性波
素子によれば、Si基板上に、Li添加ZnO圧電体層
を堆積することにより、圧電性が向上しk2の値を増大
させることができ、さらにその上にLi2O、MgO、
Al2O3の少なくとも一つを含み正のTCFを有するS
iO2保護層を堆積することにより、ZnO層の負のT
CFを相殺して素子全体のTCFを零にすることがで
き、挿入損失が小さく温度安定性に優れた高周波フィル
タ、発振器などの通信デバイスを実現することができ
る。As described above, according to the surface acoustic wave device of the present invention, by depositing the Li-doped ZnO piezoelectric layer on the Si substrate, the piezoelectricity is improved and the value of k 2 is increased. And Li 2 O, MgO,
S containing at least one of Al 2 O 3 and having a positive TCF
By depositing an iO 2 protective layer, the negative T
By canceling CF, the TCF of the entire element can be reduced to zero, and a communication device such as a high-frequency filter or an oscillator having low insertion loss and excellent temperature stability can be realized.
【図1】本発明の一実施例を示すLi添加ZnO圧電体
層を有する表面弾性波素子の断面図である。FIG. 1 is a cross-sectional view of a surface acoustic wave device having a Li-doped ZnO piezoelectric layer according to an embodiment of the present invention.
【図2】本発明の一実施例を示すLi添加ZnO圧電体
層およびLi2O、Al2O3を含んだSiO2保護層を有
する表面弾性波素子の断面図である。FIG. 2 is a sectional view of a surface acoustic wave device having a Li-doped ZnO piezoelectric layer and a SiO 2 protective layer containing Li 2 O and Al 2 O 3 according to an embodiment of the present invention.
1.(100)Si基板 2.SiO2酸化膜層 3.(001)ZnO圧電体層 4.IDT電極 5.IDT電極 11.(100)Si基板 12.SiO2酸化膜層 13.(001)ZnO圧電体層 14.IDT電極 15.IDT電極 16.SiO2保護層1. (100) Si substrate 2. SiO 2 oxide film layer (001) ZnO piezoelectric layer IDT electrode 5. IDT electrode 11. (100) Si substrate 12. SiO 2 oxide film layer 13. 13. (001) ZnO piezoelectric layer IDT electrode 15. IDT electrode 16. SiO 2 protective layer
───────────────────────────────────────────────────── フロントページの続き (72)発明者 宮澤 弘 長野県諏訪市大和3丁目3番5号 セイコ ーエプソン株式会社内 Fターム(参考) 5J097 AA06 AA21 AA23 DD29 EE08 FF02 FF05 HA02 HA03 KK09 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiroshi Miyazawa 3-3-5 Yamato, Suwa City, Nagano Prefecture Seiko Epson Corporation F-term (reference) 5J097 AA06 AA21 AA23 DD29 EE08 FF02 FF05 HA02 HA03 KK09
Claims (5)
基板上の二酸化珪素からなるバッファ層と、前記二酸化
珪素バッファ層上の酸化亜鉛からなる圧電体層とからな
り、前記酸化亜鉛圧電体層の直下または直上にインター
ディジタル型電極を形成することを特徴とする表面弾性
波素子。1. A (100) silicon substrate, comprising: a buffer layer made of silicon dioxide on the silicon substrate; and a piezoelectric layer made of zinc oxide on the silicon dioxide buffer layer. A surface acoustic wave device comprising an interdigital electrode formed immediately below or directly above.
i、Cu、Agの少なくとも一つで置換した組成を有す
ることを特徴とする請求項1記載の表面弾性波素子。2. A method according to claim 1, wherein said zinc oxide piezoelectric layer has a part of Zn
2. The surface acoustic wave device according to claim 1, having a composition substituted by at least one of i, Cu, and Ag.
コン基板に垂直に配向し、かつa軸が前記シリコン基板
に平行な面内で配向したエピタキシャル膜であることを
特徴とする請求項1記載の表面弾性波素子。3. The zinc oxide piezoelectric layer is an epitaxial film having a c-axis oriented perpendicular to the silicon substrate and an a-axis oriented in a plane parallel to the silicon substrate. Item 3. A surface acoustic wave device according to item 1.
からなる保護層を有することを特徴とする請求項1記載
の表面弾性波素子。4. The surface acoustic wave device according to claim 1, further comprising a protective layer made of silicon dioxide on said zinc oxide piezoelectric layer.
Li2O、MgO、Al2O3の少なくとも一つを含むこ
とを特徴とする請求項4記載の表面弾性波素子。5. The silicon dioxide protective layer according to claim 1, further comprising: SiO 2 ;
Li 2 O, MgO, surface acoustic wave device according to claim 4, characterized in that it comprises at least one of Al 2 O 3.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2000002571A JP2001196895A (en) | 2000-01-11 | 2000-01-11 | Surface acoustic wave device |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2000002571A JP2001196895A (en) | 2000-01-11 | 2000-01-11 | Surface acoustic wave device |
Publications (1)
Publication Number | Publication Date |
---|---|
JP2001196895A true JP2001196895A (en) | 2001-07-19 |
Family
ID=18531666
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP2000002571A Withdrawn JP2001196895A (en) | 2000-01-11 | 2000-01-11 | Surface acoustic wave device |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP2001196895A (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2004070946A1 (en) * | 2003-02-10 | 2004-08-19 | Murata Manufacturing Co., Ltd. | Elastic boundary wave device |
US7020374B2 (en) | 2003-02-03 | 2006-03-28 | Freescale Semiconductor, Inc. | Optical waveguide structure and method for fabricating the same |
US7176903B2 (en) | 2003-10-07 | 2007-02-13 | Fujitsu Limited | Piezoelectric element and touch screen utilizing the same |
US7504910B2 (en) | 2004-04-30 | 2009-03-17 | Murata Manufacturing Co., Ltd. | Thin-film piezoelectric resonator utilizing a second or higher harmonic mode |
CN104167459A (en) * | 2014-06-11 | 2014-11-26 | 中国石油大学(华东) | Heterojunction having photoinduction position sensitivity |
CN112653420A (en) * | 2020-12-18 | 2021-04-13 | 广东广纳芯科技有限公司 | A high-speed high-frequency high-frequency low-frequency temperature coefficient narrowband filter and manufacturing method |
-
2000
- 2000-01-11 JP JP2000002571A patent/JP2001196895A/en not_active Withdrawn
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7020374B2 (en) | 2003-02-03 | 2006-03-28 | Freescale Semiconductor, Inc. | Optical waveguide structure and method for fabricating the same |
WO2004070946A1 (en) * | 2003-02-10 | 2004-08-19 | Murata Manufacturing Co., Ltd. | Elastic boundary wave device |
US7471027B2 (en) | 2003-02-10 | 2008-12-30 | Murata Manufacturing Co., Ltd. | Elastic boundary wave device |
US7176903B2 (en) | 2003-10-07 | 2007-02-13 | Fujitsu Limited | Piezoelectric element and touch screen utilizing the same |
US7504910B2 (en) | 2004-04-30 | 2009-03-17 | Murata Manufacturing Co., Ltd. | Thin-film piezoelectric resonator utilizing a second or higher harmonic mode |
CN104167459A (en) * | 2014-06-11 | 2014-11-26 | 中国石油大学(华东) | Heterojunction having photoinduction position sensitivity |
CN104167459B (en) * | 2014-06-11 | 2015-12-02 | 中国石油大学(华东) | A kind of have heterojunction of photoinduction position sensing and preparation method thereof |
CN112653420A (en) * | 2020-12-18 | 2021-04-13 | 广东广纳芯科技有限公司 | A high-speed high-frequency high-frequency low-frequency temperature coefficient narrowband filter and manufacturing method |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP3777931B2 (en) | Surface acoustic wave device | |
CN1229917C (en) | Sound wave resonator and method for its operation when temperature changes to maintain harmonic vibration | |
US6239536B1 (en) | Encapsulated thin-film resonator and fabrication method | |
US7105980B2 (en) | Saw filter device and method employing normal temperature bonding for producing desirable filter production and performance characteristics | |
EP0616426B1 (en) | Surface acoustic wave device having a lamination structure | |
CN100511986C (en) | Elasticity surface wave device and method of manufacturing the same | |
JP2001196896A (en) | Surface acoustic wave device | |
TW202044757A (en) | High-order mode surface acoustic wave device | |
EP0534355B1 (en) | Method of manufacturing a surface acoustic wave device | |
US7105880B2 (en) | Electronic device and method of fabricating the same | |
JP4016583B2 (en) | Piezoelectric thin film resonator, filter and electronic device | |
US20220385267A1 (en) | Surface acoustic wave device with high electromechanical coupling coefficient based on double-layer electrodes and preparation method thereof | |
US4501987A (en) | Surface acoustic wave transducer using a split-finger electrode on a multi-layered substrate | |
JP2001196895A (en) | Surface acoustic wave device | |
CN114584101B (en) | Surface acoustic wave resonator and method for manufacturing the same, and surface acoustic wave filter | |
JP2006135443A (en) | Surface acoustic wave device and method of manufacturing surface acoustic wave device | |
CN107171653A (en) | A kind of SAW device with high electromechanical coupling factor and high center frequency | |
KR101082201B1 (en) | Surface acoustic wave device | |
JPH05183373A (en) | Electrode material for surface acoustic wave element | |
CN114584097A (en) | Surface acoustic wave resonator, method for manufacturing the same, and surface acoustic wave filter | |
JP2020057952A (en) | Surface acoustic wave device and manufacturing method of the same | |
JP3780791B2 (en) | Surface acoustic wave device | |
JPH05254991A (en) | Thin film laminated crystal and method for manufacturing the same | |
JP2000196404A (en) | Piezoelectric resonator | |
KR100323802B1 (en) | Method of fabrication acoustic wave device and acoustic wave device using the same |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
A300 | Withdrawal of application because of no request for examination |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 20070403 |