JPS59141813A - Thin film piezoelectric oscillator - Google Patents
Thin film piezoelectric oscillatorInfo
- Publication number
- JPS59141813A JPS59141813A JP1565183A JP1565183A JPS59141813A JP S59141813 A JPS59141813 A JP S59141813A JP 1565183 A JP1565183 A JP 1565183A JP 1565183 A JP1565183 A JP 1565183A JP S59141813 A JPS59141813 A JP S59141813A
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- piezoelectric
- electrode
- silicon
- upper electrode
- 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
- 239000010409 thin film Substances 0.000 title claims abstract description 68
- 239000000758 substrate Substances 0.000 claims abstract description 14
- 238000000605 extraction Methods 0.000 claims description 5
- 239000011810 insulating material Substances 0.000 claims description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract description 20
- 229910052710 silicon Inorganic materials 0.000 abstract description 20
- 239000010703 silicon Substances 0.000 abstract description 20
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 abstract description 8
- 229910052796 boron Inorganic materials 0.000 abstract description 8
- 239000000463 material Substances 0.000 abstract description 6
- 239000002131 composite material Substances 0.000 abstract description 3
- 239000010408 film Substances 0.000 abstract description 3
- 238000005530 etching Methods 0.000 description 6
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 5
- YCIMNLLNPGFGHC-UHFFFAOYSA-N catechol Chemical compound OC1=CC=CC=C1O YCIMNLLNPGFGHC-UHFFFAOYSA-N 0.000 description 4
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 238000007740 vapor deposition Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 238000005468 ion implantation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 239000011148 porous material Substances 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 devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
- H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
- H03H9/172—Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume
- H03H9/174—Membranes
Landscapes
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
Abstract
Description
【発明の詳細な説明】
本発明は圧電薄膜を用いたＶＨＦ、ＵＨＦ 用高周波
圧電振動子に関し、特にホウ素を高濃度にドープしたシ
リコン薄膜と圧電薄膜との組合せからなる複合構造の振
動部位を有する薄膜圧電振動子に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high frequency piezoelectric vibrator for VHF and UHF using a piezoelectric thin film, and in particular has a vibrating part of a composite structure consisting of a combination of a silicon thin film doped with boron at a high concentration and a piezoelectric thin film. This invention relates to thin film piezoelectric vibrators.
一般に数十ＭＨ２以上のような高い周波数で使用される
圧電振動子は、振動モードとして板面が厚さに比して十
分広い圧電性薄板の厚み振動を使用する。Generally, piezoelectric vibrators used at high frequencies, such as several tens of MH2 or more, use thickness vibration of a piezoelectric thin plate whose surface is sufficiently wide compared to its thickness as a vibration mode.
厚み振動の共振周波数は圧電性薄板の厚さに反比例する
ので高い周波数で使用するためには厚さを薄くしなけれ
ばならないが、厚さが４０ミクロン程度以下になると平
行平面研磨などの加工が非常に困難となる。したがって
バルク圧電結晶或いは圧電セラミックを用いて５０ＭＨ
２以上の厚み振動圧電振動子を量産することは困難であ
る。The resonant frequency of thickness vibration is inversely proportional to the thickness of the piezoelectric thin plate, so in order to use it at high frequencies, the thickness must be made thinner, but when the thickness is less than about 40 microns, processing such as parallel plane polishing is required. It becomes very difficult. Therefore, using bulk piezoelectric crystal or piezoelectric ceramic, 50MH
It is difficult to mass produce vibrating piezoelectric vibrators with a thickness of two or more.
振動部分の厚さを薄くして５０■号以上の厚み振動圧電
振動子を得る方法としては第１図、第２図の構造の薄膜
圧電振動子が公知である。この薄膜圧電振動子は基板１
１の上に半導体或いは絶縁体の薄膜部材１３を形成した
後、エツチングによって基板１１に空孔１２を作成し、
さらに薄膜部材１３の上に順に下地電極１４、圧電薄膜
１５、上部電極１６を形成することによって製造するも
ので、一般に非圧電性である薄膜部材１３と圧電薄膜１
５とからなる複合ダイアフラムが周縁部を基板１１によ
って支持された構造となっている。As a method for obtaining a vibrating piezoelectric vibrator having a thickness of 50 cm or more by reducing the thickness of the vibrating portion, a thin film piezoelectric vibrator having the structure shown in FIGS. 1 and 2 is known. This thin film piezoelectric vibrator has a substrate 1
After forming a semiconductor or insulator thin film member 13 on the substrate 1, holes 12 are created in the substrate 11 by etching,
Furthermore, it is manufactured by sequentially forming a base electrode 14, a piezoelectric thin film 15, and an upper electrode 16 on the thin film member 13. Generally, the thin film member 13, which is non-piezoelectric, and the piezoelectric thin film 1
A composite diaphragm consisting of 5 is supported at its peripheral portion by a substrate 11.
第１図、第２図の構造の薄膜圧電振動子において、基板
１１としては一般に表面が（ｉｏｏ ）面であるような
シリコンが用いられ、エチレンジアミン。In the thin film piezoelectric vibrator having the structure shown in FIGS. 1 and 2, the substrate 11 is generally made of silicon whose surface is an (ioo) plane, and is made of ethylenediamine.
ピロカテコール、水からなるエツチング液（以下ＥＤＰ
液という）或いは水酸化カリウム（ＫＯＨ）水溶液によ
る異方性エツチングを利用して精密に空孔１２を作成す
ることができる。Etching liquid (EDP) consisting of pyrocatechol and water
The pores 12 can be precisely created using anisotropic etching using an aqueous potassium hydroxide (KOH) solution or an aqueous solution of potassium hydroxide (KOH).
薄膜部材１３としては上記のＥＤＰ液或いはＫＯＨ水溶
液に対してできるだけエツチング速度の小さい材料が必
要であり、従来この目的に適４合する材料として種々の
酸化物、窒化物なども提案されているが、ホウ素を高濃
度にドープしたシリコン薄膜が最も理想的な材料である
。なぜならば、ホウ素を高濃度にドープしたシリコン薄
膜はシリコン基板の上にエピタキシャル成長、拡散、イ
オン注入などによって作成する単結晶であるので、機械
的強度が大きく、音響的クォリティ・ファクタＱが大き
いからである。The thin film member 13 needs to be made of a material that has an etching rate as low as possible with respect to the above-mentioned EDP liquid or KOH aqueous solution, and various oxides and nitrides have been proposed as materials suitable for this purpose. , a silicon thin film doped with a high concentration of boron is the most ideal material. This is because a silicon thin film doped with boron at a high concentration is a single crystal formed on a silicon substrate by epitaxial growth, diffusion, ion implantation, etc., so it has high mechanical strength and a large acoustic quality factor Q. be.
しかし、ホウ素を高濃度ζこドープしたシリコン薄膜は
導電率が非常に大きいため第１図、第２図に示した従来
の薄膜圧電振動子では次のような重大な欠点を有してい
た。すなわち、このような振動子ではワイヤ・ボンディ
ングなどによる配線のために上部電極の引き出し電極１
７が必要であるが、この引き出し電極１７とシリコン薄
膜との間の容量が振動子に並列に加わる結果、振動子の
容量比が見かけ上大きくなってしまうという欠点である
。However, since a silicon thin film doped with boron at a high concentration has a very high conductivity, the conventional thin film piezoelectric vibrator shown in FIGS. 1 and 2 had the following serious drawbacks. In other words, in such a vibrator, the lead electrode 1 of the upper electrode is used for wiring such as wire bonding.
However, as a result of the capacitance between the extraction electrode 17 and the silicon thin film being applied in parallel to the vibrator, the capacitance ratio of the vibrator becomes apparently large.
薄膜圧電振動子の上部電極の寸法は通常１００〜２００
μｍの程度であり、引き出し電極は可能な限り小さくし
ても１００μｆ２Ｌ角程度は必要であるから振動子の見
かけの容量比は２〜３倍に大きくなってしまう。このた
め従来の構造の薄膜圧電振動子を用いたのでは、発振器
の制御範囲或いはフィルタの比帯域幅を十分に広く取る
ことができなかった。The dimensions of the upper electrode of a thin film piezoelectric vibrator are usually 100 to 200.
Even if the extraction electrode is made as small as possible, it still needs to be about 100 μf2L square, so the apparent capacitance ratio of the vibrator becomes 2 to 3 times larger. For this reason, when a thin film piezoelectric vibrator having a conventional structure is used, the control range of the oscillator or the fractional bandwidth of the filter cannot be made sufficiently wide.
本発明の目的は、上記のような欠点を除いた薄膜圧電振
動子を提供することであり、本発明の最たる特徴は上部
電極の引き出し電極と圧電薄膜との間に絶縁材料の薄膜
を有する構造にある。An object of the present invention is to provide a thin film piezoelectric vibrator that eliminates the above-mentioned drawbacks, and the most important feature of the present invention is a structure in which a thin film of an insulating material is provided between the lead electrode of the upper electrode and the piezoelectric thin film. It is in.
すなわち、本発明は薄膜部材と該薄膜部材の上に順に下
地電極、圧電薄膜、上部電極が形成された構造の振動部
位を持ち、該振動部位にあたる部分が取り除かｉもだ基
板によって該振動部位の外縁部が支持されている構造の
薄膜圧電振動子において、上部電極の引出し電極と圧電
薄膜との間に絶縁材料の薄膜を有することを特徴とする
薄膜圧電振動子である。That is, the present invention has a vibrating part having a structure in which a thin film member and a base electrode, a piezoelectric thin film, and an upper electrode are formed in order on the thin film member, and the part corresponding to the vibrating part is removed and the vibrating part is moved by a substrate. The thin film piezoelectric vibrator has a structure in which the outer edge is supported, and is characterized by having a thin film of an insulating material between the lead electrode of the upper electrode and the piezoelectric thin film.
以下、実施例にしたがって本発明の詳細な説明する。Hereinafter, the present invention will be explained in detail based on examples.
第３図、第４図に本発明の実施例の薄膜圧電振動子の構
造を示す。第３図、第４図において３１は表面が（：ｔ
ｏｏ ）面であるようなシリコン基板、３２はエツチン
グによって基板に作成した空孔、３３はホウ素を高濃度
にドープしたシリコン薄膜、３４は下地電極、３５は圧
電薄膜、３６は上部電極、３７は上部電極の引き出し電
極であり、３８は本発明の特徴であるところの絶縁材薄
膜である。本発明の趣旨から言って絶縁材薄膜３８は誘
電率のできるだけ小さい材料が望ましく 、８１０２
、 Ｓｔ、Ｎ４など半導体工業分野でその製法が確立さ
れている種々の酸化物、窒化物などを使用することがで
きる。第３図、第４図のような本発明の薄膜圧電振動子
では絶縁材薄膜３８を有する結果、上部電極の引き出し
電極とシリコン薄膜との間の容量は振動部位における容
量に比べて非常に小さくなり、したがって従来のように
見かけの容量比が大きくなることがなく、従来に比べて
制御範囲の広い発撮器或いは比帯域の広いフィルタが実
現できる。FIGS. 3 and 4 show the structure of a thin film piezoelectric vibrator according to an embodiment of the present invention. In Figures 3 and 4, 31 has a surface (:t
oo) surface, 32 is a hole created in the substrate by etching, 33 is a silicon thin film doped with boron at a high concentration, 34 is a base electrode, 35 is a piezoelectric thin film, 36 is an upper electrode, 37 is a This is an extraction electrode of the upper electrode, and 38 is an insulating thin film which is a feature of the present invention. In view of the spirit of the present invention, the insulating thin film 38 is desirably made of a material with a dielectric constant as low as possible.
Various oxides and nitrides whose manufacturing methods have been established in the semiconductor industry, such as , St, and N4, can be used. As a result of the thin film piezoelectric vibrator of the present invention as shown in FIGS. 3 and 4 having the insulating thin film 38, the capacitance between the lead electrode of the upper electrode and the silicon thin film is very small compared to the capacitance at the vibrating part. Therefore, the apparent capacitance ratio does not increase as in the conventional case, and it is possible to realize an oscillator with a wider control range or a filter with a wider fractional band than in the conventional case.
以下に本発明の実施例についてさらに具体的ｔこ説明す
る。Examples of the present invention will be described in more detail below.
表面が（１００）面であるようなシリコン基板の表面に
ホウ素を１０２０／ｃｎＬ８の濃度にドープしたシリコ
ン薄膜を３μｍの厚さにエピタキシャル成長させた。次
にシリコン基板の裏面に形成したＳｉ、Ｎ４薄膜をマ、
スクと′して振動部位にあたるシリコン基板ヲエチレン
ジアミン、ピロカテコール及び水からなるエツチング液
を用いて裏面からエツチングを行ない、シリコン薄膜の
ダイアフラムを形成した。次にシリコン薄膜上に蒸着法
でＡｕ／Ｃｒ 電極を形成し、続いてスパッタリング法
で厚さ４μｍの酸化亜鉛（ＺｎＯ）薄膜を形成した。さ
らにスパッタリング法でＳ ｉｏ２絶縁材薄膜を形成し
た後、蒸着法でＭ電極を形成して第３図、第４図の構造
の薄膜圧電振動子を製造した。全く同様の工程で５ｉｎ
２絶縁膜を有しない従来構造の振動子を同時に製造した
。２種期の振動子の特性を測定した結果、従来構造の振
動子の容量比は６０、本発明の構造を用いた振動子の容
量比は３０であり、本発明の有用性が実証された。A silicon thin film doped with boron at a concentration of 1020/cnL8 was epitaxially grown on the surface of a silicon substrate having a (100) plane to a thickness of 3 μm. Next, the Si and N4 thin films formed on the back side of the silicon substrate are
A silicon substrate serving as a vibration site was etched from the back side using an etching solution consisting of ethylenediamine, pyrocatechol, and water to form a silicon thin film diaphragm. Next, an Au/Cr 2 electrode was formed on the silicon thin film by vapor deposition, and then a 4 μm thick zinc oxide (ZnO) thin film was formed by sputtering. Furthermore, after forming an Sio2 insulating thin film by sputtering, an M electrode was formed by vapor deposition to produce a thin film piezoelectric vibrator having the structure shown in FIGS. 3 and 4. 5 inches in exactly the same process
2. A vibrator with a conventional structure without an insulating film was manufactured at the same time. As a result of measuring the characteristics of the two types of vibrators, the capacity ratio of the vibrator with the conventional structure was 60, and the capacity ratio of the vibrator using the structure of the present invention was 30, demonstrating the usefulness of the present invention. .
以上のように本発明によれば従来構造に比べて容量比の
小さい薄膜圧電振動子の提供が可能であり、本発明の薄
膜圧電振動子を用いれば、制御範囲の広い発振器或いは
比帯域の広いフィルタか実現できる。As described above, according to the present invention, it is possible to provide a thin film piezoelectric vibrator with a smaller capacitance ratio than the conventional structure, and by using the thin film piezoelectric vibrator of the present invention, it is possible to create an oscillator with a wide control range or a wide specific band. A filter can be implemented.
なお上記の説明においては薄膜部材としてホウ素を高濃
度にドープしたシリコン薄膜を使用した場合について説
明したが、他の薄膜部材を使用した場合にも本発明の適
用により同様の効果を得ることができる。In the above explanation, a silicon thin film doped with boron at a high concentration is used as the thin film member, but the same effect can be obtained by applying the present invention even when other thin film members are used. .
第１図、第２図は従来の薄膜圧電振動子の構造を示す図
であり、第１図は平面図、第２図は断面図である。第３
図、第４図は本発明の薄膜圧電振動子の構造を示す図で
あり、第３図は平面図、第４図は断面図である。
第１図から第４図において、１１ 、３１はシリコン基
板、１．２ 、３２は空孔、：１３ 、３３はシリコン
薄膜、１４ 、３４は下地電極、１５ 、３５は圧電薄
膜、１６ 、３６は上部電極、１７．３７は引き出し電
極、３８は絶縁材薄膜である。
第１図
第 ３ 図
躬 ４ 図FIGS. 1 and 2 are diagrams showing the structure of a conventional thin film piezoelectric vibrator, with FIG. 1 being a plan view and FIG. 2 being a sectional view. Third
4 are diagrams showing the structure of the thin film piezoelectric vibrator of the present invention, FIG. 3 is a plan view, and FIG. 4 is a sectional view. 1 to 4, 11, 31 are silicon substrates, 1.2, 32 are holes, 13, 33 are silicon thin films, 14, 34 are base electrodes, 15, 35 are piezoelectric thin films, 16, 36 is an upper electrode, 17.37 is an extraction electrode, and 38 is an insulating material thin film. Figure 1 Figure 3 Figure 4
Claims (1)
成された構造の振動部位を持ち、該振動部位にあたる部
分が取り除かれた基板によって該振動部位の外縁部が支
持されている構造の薄膜圧電振動子において、上部電極
の引出し電極と圧電薄膜との間に絶縁材料の薄膜を有す
ることを特徴とする薄膜圧電振動子。A thin film having a structure in which a vibrating part has a structure in which a base electrode, a piezoelectric thin film, and an upper electrode are formed in order on a thin film member, and the outer edge of the vibrating part is supported by a substrate from which a portion corresponding to the vibrating part has been removed. A thin film piezoelectric vibrator characterized in that the piezoelectric vibrator includes a thin film of an insulating material between an extraction electrode of an upper electrode and a piezoelectric thin film.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1565183A JPS59141813A (en) | 1983-02-02 | 1983-02-02 | Thin film piezoelectric oscillator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1565183A JPS59141813A (en) | 1983-02-02 | 1983-02-02 | Thin film piezoelectric oscillator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59141813A true JPS59141813A (en) | 1984-08-14 |
| JPH0161253B2 JPH0161253B2 (en) | 1989-12-27 |
Family
ID=11894617
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1565183A Granted JPS59141813A (en) | 1983-02-02 | 1983-02-02 | Thin film piezoelectric oscillator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59141813A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5235240A (en) * | 1990-05-25 | 1993-08-10 | Toyo Communication Equipment Co., Ltd. | Electrodes and their lead structures of an ultrathin piezoelectric resonator |
| US6989723B2 (en) | 2002-12-11 | 2006-01-24 | Tdk Corporation | Piezoelectric resonant filter and duplexer |
-
1983
- 1983-02-02 JP JP1565183A patent/JPS59141813A/en active Granted
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5235240A (en) * | 1990-05-25 | 1993-08-10 | Toyo Communication Equipment Co., Ltd. | Electrodes and their lead structures of an ultrathin piezoelectric resonator |
| US6989723B2 (en) | 2002-12-11 | 2006-01-24 | Tdk Corporation | Piezoelectric resonant filter and duplexer |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0161253B2 (en) | 1989-12-27 |
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