JP3021764B2 - Oxide superconductor thin film - Google Patents
Oxide superconductor thin filmInfo
- Publication number
- JP3021764B2 JP3021764B2 JP3115350A JP11535091A JP3021764B2 JP 3021764 B2 JP3021764 B2 JP 3021764B2 JP 3115350 A JP3115350 A JP 3115350A JP 11535091 A JP11535091 A JP 11535091A JP 3021764 B2 JP3021764 B2 JP 3021764B2
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- oxide superconductor
- atomic layer
- layer
- composition
- 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 - Lifetime
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment
Landscapes
- Inorganic Compounds Of Heavy Metals (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
- Superconductors And Manufacturing Methods Therefor (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、ミリ波・マイクロ波デ
バイス等の導体として好適な酸化物超電導体薄膜に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxide superconductor thin film suitable as a conductor for a millimeter-wave / microwave device or the like.
【０００２】[0002]
【従来の技術】５年前にＴｃ（臨界温度）が３０Ｋの
（Ｂａ，Ｌａ）−Ｏ，Ｃｕ−Ｏ等の原子層が層状に配列
したペロブスカイト関連のＫ2 Ｎ2Ｆ4 型構造のＢａ−
Ｌａ−Ｃｕ−Ｏ系超電体が発見され、その後ペロブスカ
イト関連の似た構造の、Ｔｃが液体窒素温度（７７Ｋ）
を超えるＹＢａＣｕＯ系，ＢｉＳｒＣａＣｕＯ系，Ｔｌ
ＢａＣａＣｕＯ系等の酸化物超電導体が次々に発見され
るに到って、酸化物超電導体に関して、超電導機構の解
明とともに、電力応用，強磁場応用，エレクトロニクス
応用等の実用化に向けた研究が大いに進展した。ところ
で、エレクトロニクス分野への応用には、酸化物超電導
体の薄膜化技術が必須であり、これまでに、スパッタリ
ング法，レーザー蒸着法，各種の物理気相蒸着法（ＰＶ
Ｄ法）や化学蒸着法（ＣＶＤ法）等の応用研究がなされ
てきた。しかしながら、上記のような従来法により作製
される酸化物超電導体薄膜は表面抵抗が大きく、ミリ波
・マイクロ波デバイス等に応用するには不適当なもので
あった。2. Description of the Related Art Five years ago, perovskite-related K 2 N 2 F 4 type Ba in which atomic layers of (Ba, La) —O, Cu—O, etc. having a Tc (critical temperature) of 30 K are arranged in layers. −
La-Cu-O-based superconductor was discovered, and Tc of similar structure related to perovskite was changed to liquid nitrogen temperature (77K).
YBaCuO-based, BiSrCaCuO-based, Tl
As oxide superconductors such as BaCaCuO are discovered one after another, research on oxide superconductors, including elucidation of the superconducting mechanism and practical application of electric power application, strong magnetic field application, electronics application, etc., has been greatly performed. Evolved. By the way, thinning technology of oxide superconductors is indispensable for application to the electronics field. Up to now, sputtering, laser deposition, various physical vapor deposition (PV)
D) and chemical vapor deposition (CVD). However, the oxide superconductor thin film produced by the conventional method as described above has a large surface resistance, and is unsuitable for application to millimeter-wave / microwave devices and the like.
【０００３】[0003]
【課題を解決する為の手段】本発明はかかる状況に鑑
み、表面抵抗の小さい薄膜の作製方法について、鋭意研
究を行った結果、従来のＰＶＤ法やＣＶＤ法により作製
された酸化物超電導体薄膜の表面抵抗が大きい理由は、
蒸発源に酸化物超電導体の構成元素を全て含む単一のタ
ーゲットを用い、或いは構成元素別ターゲットを同時に
蒸着させる方法により作製する為、組成制御はできるが
構造制御性が悪く、又薄膜の表面に異相が析出したりす
ることによること、即ち、酸化物超電導体を構成する原
子層の積み重ね方によって表面抵抗が著しく相違するこ
とを知見し、更に研究を重ねて本発明を完成するに到っ
たものである。即ち、本発明は、基板上に形成された、
Ｃｕを構成元素として含有する酸化物超電導体薄膜であ
って、前記薄膜の結晶のＣ軸が基板面の垂線方向に配向
しており、且つ前記薄膜の最上層に伝導性のＣｕ−Ｏ原
子層が形成されていることを特徴とするものである。In view of the foregoing, the present invention has made intensive studies on a method of forming a thin film having a small surface resistance. As a result, an oxide superconductor thin film formed by a conventional PVD method or CVD method has been obtained. The reason why the surface resistance of
Since a single target containing all the constituent elements of the oxide superconductor is used as the evaporation source, or the target is prepared by vapor deposition of the constituent elements at the same time, the composition can be controlled but the structure controllability is poor, and the surface of the thin film And that the surface resistance is significantly different depending on how the atomic layers constituting the oxide superconductor are stacked, and further studies have been completed to complete the present invention. It is a thing. That is, the present invention relates to a method of forming on a substrate,
An oxide superconductor thin film containing Cu as a constituent element, wherein a C axis of a crystal of the thin film is oriented in a direction perpendicular to a substrate surface, and a conductive Cu—O atomic layer is formed on an uppermost layer of the thin film. Are formed.
【０００４】本発明の酸化物超電導体薄膜とは、Ｂｉ2
Ｓｒ2 Ｃａ2 Ｃｕ3 ＯY 組成、又はＢｉ2 Ｓｒ2 Ｃａ1
Ｃｕ2 ＯY 組成、又はＴｌ2 Ｂａ2 Ｃａ2 Ｃｕ3 ＯZ 組
成、又はＴｌ2 Ｂａ2 Ｃａ1 Ｃｕ2 ＯZ 組成、又は一般
式ＬｎＢａ2 Ｃｕ3Ｏ7-x （式中ＬｎはＹ及びランタノ
イド金属元素の中の１元素又は複数元素）で示される組
成等のＣｕを構成元素として含有する酸化物超電導体全
般を指すものである。前記のＢｉ2 Ｓｒ2 Ｃａ2 Ｃｕ3
ＯY 〔以下Ｂｉ系（２２２３）と略記〕組成又はＢｉ2
Ｓｒ2 Ｃａ1 Ｃｕ2 ＯY 〔以下Ｂｉ系（２２１２）と略
記〕組成の酸化物超電導体は、図１イ，ロにその結晶の
単位格子をそれぞれ示したように、前者はＢｉ−Ｏ，Ｂ
ｉ−Ｏ，Ｓｒ−Ｏ，Ｃｕ−Ｏ，Ｃａ，ＣｕＯ鎖，Ｃａ，
Ｃｕ−Ｏ，Ｓｒ−Ｏ，Ｂｉ−Ｏ，Ｂｉ−Ｏ，Ｓｒ−Ｏ，
Ｃｕ−Ｏ，Ｃａ，ＣｕＯ鎖，Ｃａ，Ｃｕ−Ｏ，Ｓｒ−Ｏ
の各々の原子層が順次積層して単位格子を作るペロブス
カイト構造の複合酸化物で、この酸化物超電導体におけ
る伝導性Ｃｕ−Ｏ原子層とは図１イで矢印で指したＳｒ
−Ｏ原子層とＣａ原子層とに挟まれたＣｕ−Ｏ原子層の
ことである。[0004] The oxide superconductor thin film of the present invention refers to Bi 2
Sr 2 Ca 2 Cu 3 O Y composition or Bi 2 Sr 2 Ca 1
Cu 2 O Y composition, or Tl 2 Ba 2 Ca 2 Cu 3 O Z composition, or Tl 2 Ba 2 Ca 1 Cu 2 O Z composition, or the general formula LnBa 2 Cu 3 O 7-x (where Ln is Y and It refers to all oxide superconductors containing Cu as a constituent element, such as a composition represented by one or more of the lanthanoid metal elements. Bi 2 Sr 2 Ca 2 Cu 3
O Y [hereinafter abbreviated as Bi system (2223)] composition or Bi 2
An oxide superconductor having a composition of Sr 2 Ca 1 Cu 2 O Y [hereinafter abbreviated as Bi-based (2212)] has a unit cell of crystal as shown in FIGS. B
i-O, Sr-O, Cu-O, Ca, CuO chain, Ca,
Cu-O, Sr-O, Bi-O, Bi-O, Sr-O,
Cu-O, Ca, CuO chain, Ca, Cu-O, Sr-O
Is a composite oxide having a perovskite structure in which each atomic layer is sequentially laminated to form a unit lattice. The conductive Cu—O atomic layer in this oxide superconductor is Sr indicated by an arrow in FIG.
It is a Cu-O atomic layer sandwiched between a -O atomic layer and a Ca atomic layer.
【０００５】又、後者はＢｉ−Ｏ，Ｂｉ−Ｏ，Ｓｒ−
Ｏ，Ｃｕ−Ｏ，Ｃａ，Ｃｕ−Ｏ，Ｓｒ−Ｏ，Ｂｉ−Ｏ，
Ｂｉ−Ｏ，Ｓｒ−Ｏ，Ｃｕ−Ｏ，Ｃａ，Ｃｕ−Ｏ，Ｓｒ
−Ｏの各々の原子層が順次積層して単位格子を作るペロ
ブスカイト構造の複合酸化物で、伝導性Ｃｕ−Ｏ原子層
とは矢印で指したやはりＳｒ−Ｏ原子層とＣａ原子層で
挟まれたＣｕ−Ｏ原子層である。又、Ｔｌ2 Ｂａ2 Ｃａ
2 Ｃｕ3 ＯZ 〔以下Ｔｌ系（２２２３）と略記〕組成、
又はＴｌ2 Ｂａ2 Ｃａ1 Ｃｕ2 ＯZ 〔以下Ｔｌ系（２２
１２）と略記〕組成の酸化物超電導体は、図２イ，ロに
その結晶の単位格子をそれぞれ示したように図１イ，ロ
に示したＢｉ系（２２２３）組成及びＢｉ系（２２１
２）組成の酸化物超電導体のＢｉをＴｌに、ＳｒをＢａ
にそれぞれ代えた酸化物超電導体であって、伝導性Ｃｕ
−Ｏ原子層はＢａ−Ｏ原子層とＣａ原子層で挟まれた矢
印で指したＣｕ−Ｏ原子層である。尚、前記のＣｕＯ鎖
とは、Ｃｕサイトの上下に頂点酸素を持たず、Ｃｕ原子
とＯ原子とが交互に正方形ＣｕＯ4 を形成したもので、
Ｃｕ原子が平面型４配位をとっているものである。The latter is Bi-O, Bi-O, Sr-
O, Cu-O, Ca, Cu-O, Sr-O, Bi-O,
Bi-O, Sr-O, Cu-O, Ca, Cu-O, Sr
-O is a composite oxide having a perovskite structure in which each atomic layer is sequentially laminated to form a unit cell. The conductive Cu-O atomic layer is also sandwiched between the Sr-O atomic layer and the Ca atomic layer indicated by arrows. A Cu—O atomic layer. Also, Tl 2 Ba 2 Ca
2 Cu 3 O Z [hereinafter abbreviated as Tl (2223)] composition,
Or Tl 2 Ba 2 Ca 1 Cu 2 O Z [hereinafter referred to as Tl-based (22
12) The oxide superconductor having the composition shown in FIGS. 2A and 2B shows the Bi-based (2223) composition and the Bi-based (2211) shown in FIGS.
2) Bi of the composition oxide superconductor is set to Tl and Sr is set to Ba.
Oxide superconductors, each of which has conductive Cu
The -O atomic layer is a Cu-O atomic layer indicated by an arrow sandwiched between a Ba-O atomic layer and a Ca atomic layer. Incidentally, the above-mentioned CuO chain has no vertex oxygen above and below the Cu site, and a Cu atom and an O atom alternately form a square CuO 4 ,
Cu atoms have a planar four-coordinate configuration.
【０００６】又、一般式ＬｎＢａ2 Ｃｕ3 Ｏ7-x （式中
ＬｎはＹ及びランタノイド金属元素の中の１元素又は複
数元素）で示される組成の酸化物超電導体の結晶の単位
格子は図３に示したように、例えばＣｕ−Ｏ，Ｂａ−
Ｏ，ＣｕＯ鎖，Ｂａ−Ｏ，Ｃｕ−Ｏ，Ｙ，Ｃｕ−Ｏ，Ｂ
ａ−Ｏ，ＣｕＯ鎖，Ｂａ−Ｏ，Ｃｕ−Ｏ，Ｙの各々の原
子層を順次積み上げて形成したものであって、この酸化
物超電導体の伝導性Ｃｕ−Ｏ原子層は、Ｂａ−Ｏ原子層
とＹ原子層とに挟まれた矢印で指したＣｕ−Ｏ原子面で
ある。尚、上記のＣｕＯ鎖とは、ＣｕとＯ原子とが交互
に直線状に配列したもので、Ｃｕが直線型２配位をとっ
ている。これはＣｕを含むが、超電導状態にならない層
である。又前記一般式中のＬｎはＹ及びランタノイド金
属元素の中の１種又は複数種の元素で、ランタノイド金
属元素とは、Ｌａ，Ｃｅ，Ｐｒ，Ｎｄ，Ｅｒ，Ｈｏ等で
ある。本発明の酸化物超電導体薄膜は、酸化物超電導体
を構成する原子層の伝導性のＣｕ−Ｏ原子層を薄膜の最
上層に配置するもので、かかる積層構造の酸化物超電導
体薄膜は、例えば分子線エピタキシー（ＭＢＥ）装置を
用い、構成元素を所定の順序で１原子層ずつ蒸着させて
作製することができる。The unit cell of a crystal of an oxide superconductor having a composition represented by a general formula LnBa 2 Cu 3 O 7-x (where Ln is one or more of Y and a lanthanoid metal element) is shown in FIG. As shown in FIG. 3, for example, Cu—O, Ba—
O, CuO chain, Ba-O, Cu-O, Y, Cu-O, B
a-O, CuO chains, Ba-O, Cu-O, Y are formed by sequentially stacking atomic layers. The conductive Cu-O atomic layer of this oxide superconductor is formed of Ba-O It is a Cu-O atomic plane pointed by an arrow between an atomic layer and a Y atomic layer. The above-mentioned CuO chain is one in which Cu and O atoms are alternately arranged in a linear manner, and Cu has a linear two-coordination. This is a layer containing Cu but not in a superconducting state. Ln in the above general formula is one or more of Y and the lanthanoid metal element, and the lanthanoid metal element is La, Ce, Pr, Nd, Er, Ho or the like. The oxide superconductor thin film of the present invention is one in which a conductive Cu-O atomic layer of an atomic layer constituting the oxide superconductor is arranged on the uppermost layer of the thin film. For example, it can be manufactured by using a molecular beam epitaxy (MBE) apparatus to deposit constituent elements one by one atomic layer in a predetermined order.
【０００７】以下に、本発明の酸化物超電導体薄膜の製
造方法の具体例を図を参照して説明する。図４は本発明
の薄膜を製造する為の分子線エピタキシー（ＭＢＥ）装
置の要部説明図である。このＭＢＥ装置は、チャンバー
１内に、蒸発源を入れる複数のセルａ，ｂ，ｃ，ｄと前
記蒸発源から発生するガスを堆積させる為の基板２とを
対向配置させて構成したものである。前記セルａ〜ｄに
は、蒸発源を加熱する為のヒーター３と基板２への蒸着
量を制御する為のシャッターイ，ロ，ハ，ニと蒸発速度
をモニターする水晶振動式膜厚計４がそれぞれ設けられ
ている。前記膜厚計４の計測結果はヒーター３及びシャ
ッターイ〜ニにフィードバックされて、基板２上に蒸着
する原子層の種類及び厚さが自動的に制御される。又酸
化物超電導体薄膜を形成する基板２にもヒーター13が付
いていて、基板温度をコントロールして酸化物超電導体
薄膜の結晶構造が調整される。チャンバー１内は、排気
用ポンプ５により圧力調節バルブ６を通して所定圧力に
排気される。セルａ〜ｄ近傍は蒸発源の酸化防止の為、
５×１０-7Ｔｏｒｒの高真空に保持され、他方、基板２
近傍には、基板２上に形成される蒸着膜への酸素取込み
が促進されるように、酸素原子を遊離し得るＯ3 やＮ2
Ｏ等の活性ガスをボンベ７からマスフローメーター８を
通しノズル９より吹付ける。基板２とセルａ〜ｄ間には
双方の真空度の差を保持する為差動排気板10が配置され
ている。A specific example of the method for producing an oxide superconductor thin film of the present invention will be described below with reference to the drawings. FIG. 4 is an explanatory view of a main part of a molecular beam epitaxy (MBE) apparatus for producing a thin film of the present invention. This MBE apparatus has a structure in which a plurality of cells a, b, c, and d for accommodating an evaporation source and a substrate 2 for depositing a gas generated from the evaporation source are arranged to face each other in a chamber 1. . The cells a to d are provided with a heater 3 for heating the evaporation source, shutters B, C, D for controlling the amount of vapor deposition on the substrate 2 and a quartz vibrating film thickness meter 4 for monitoring the evaporation rate. Are provided respectively. The measurement result of the film thickness meter 4 is fed back to the heater 3 and the shutters I to D to automatically control the type and thickness of the atomic layer deposited on the substrate 2. The substrate 2 on which the oxide superconductor thin film is to be formed is also provided with a heater 13 for controlling the substrate temperature to adjust the crystal structure of the oxide superconductor thin film. The inside of the chamber 1 is evacuated to a predetermined pressure through a pressure control valve 6 by an exhaust pump 5. In the vicinity of the cells a to d, in order to prevent oxidation of the evaporation source,
The substrate is kept in a high vacuum of 5 × 10 −7 Torr, while the substrate 2
In the vicinity, O 3 or N 2 which can release oxygen atoms is provided so that oxygen incorporation into the deposited film formed on the substrate 2 is promoted.
An active gas such as O is blown from a nozzle 9 through a mass flow meter 8 from a cylinder 7. A differential pumping plate 10 is arranged between the substrate 2 and the cells a to d in order to maintain a difference between the two degrees of vacuum.
【０００８】次に、前記ＭＢＥ装置を用いて、図１イに
示した結晶構造の酸化物超電導体薄膜を基板上に形成す
る方法について説明する。図４に示した装置のセル、
ａ，ｂ，ｃ，ｄに蒸発源として、例えばＢｉ2 Ｏ3 ，Ｓ
ｒ，Ｃａ，Ｃｕをそれぞれ充填し、前記セル、ａ〜ｄの
各々のシャッター（イ）〜（ニ）を、例えばハ，ニ，
ハ，ニ，ロ，イ，イ，ロ，ニ，ハ，ニ，ハ，ニ，ロ，
イ，イ，ロ，ニの順序で１個づつ所定時間開いて、基板
上に単位格子を構成するＣａ，ＣｕＯ鎖，Ｃａ，Ｃｕ−
Ｏ，Ｓｒ−Ｏ，Ｂｉ−Ｏ，Ｂｉ−Ｏ，Ｓｒ−Ｏ，Ｃｕ−
Ｏ，Ｃａ，ＣｕＯ鎖，Ｃａ，Ｃｕ−Ｏ，Ｓｒ−Ｏ，Ｂｉ
−Ｏ，Ｂｉ−Ｏ，Ｓｒ−Ｏ，Ｃｕ−Ｏの原子層を順次積
み上げて単位格子を形成し、この操作を複数回繰り返し
て最上層にＣｕ−Ｏ層が形成されたＢｉ系（２２２３）
組成の酸化物超電導体薄膜を製造する。上記において、
最上層に形成するＣｕ−Ｏ原子層は、単位格子中に現れ
るＳｒ−Ｏ原子層とＣａ原子層に挟まれた伝導性Ｃｕ−
Ｏ原子層である。又酸化物超電導体薄膜は、前記単位格
子の整数倍を積み上げて製造すると薄膜全体の電荷が中
性化されるので特性上好ましく、その場合基板上に形成
される第一層は、必然的にＳｒ−Ｏ又はＣａ原子層のい
ずれかの層であることが要求される。Next, a method for forming an oxide superconductor thin film having a crystal structure shown in FIG. 1A on a substrate by using the MBE apparatus will be described. A cell of the device shown in FIG. 4,
a, b, c, and d as evaporation sources, for example, Bi 2 O 3 , S
r, Ca, and Cu, respectively, and shutters (a) to (d) of the cells, a to d, for example, c, d,
Ha, ni, ro, i, i, ro, ni, ha, ni, ha, ni, ro,
Open one by one in the order of b, b, c, and c to form a unit cell on the substrate.
O, Sr-O, Bi-O, Bi-O, Sr-O, Cu-
O, Ca, CuO chain, Ca, Cu-O, Sr-O, Bi
-A, Bi-O (2223) in which atomic layers of -O, Bi-O, Sr-O, and Cu-O are sequentially stacked to form a unit cell, and this operation is repeated a plurality of times to form a Cu-O layer on the uppermost layer.
An oxide superconductor thin film having a composition is manufactured. In the above,
The Cu—O atomic layer formed on the uppermost layer is a conductive Cu—O layer sandwiched between the Sr—O atomic layer and the Ca atomic layer that appear in the unit cell.
It is an O atomic layer. When the oxide superconductor thin film is manufactured by stacking an integral multiple of the unit cell, the charge of the entire thin film is neutralized, so that it is preferable in terms of characteristics. It is required to be a layer of either Sr-O or Ca atomic layer.
【０００９】又図１ロに示した結晶構造のＢｉ系（２２
１２）組成の酸化物超電導体薄膜は、シャッター（イ）
〜（ニ）をハ，ニ，ロ，イ，イ，ロ，ニ，ハ，ニ，ロ，
イ，イ、ロ、ニの順序で１個づつ所定時間開いて、基板
上に単位格子を構成するＣａ，Ｃｕ−Ｏ，Ｓｒ−Ｏ，Ｂ
ｉ−Ｏ，Ｂｉ−Ｏ，Ｓｒ−Ｏ，Ｃｕ−Ｏ，Ｃａ，Ｃｕ−
Ｏ，Ｓｒ−Ｏ，Ｂｉ−Ｏ，Ｂｉ−Ｏ，Ｓｒ−Ｏ，Ｃｕ−
Ｏの各々の原子層を順次積み上げて単位格子を形成し、
この操作を複数回繰り返して最上層にＣｕ−Ｏ原子層を
形成して製造される。上記において、最上層に形成する
Ｃｕ−Ｏ原子層は、単位格子中に現れるＳｒ−Ｏ原子層
とＣａ原子層に挟まれた伝導性Ｃｕ−Ｏ原子層であり、
基板上に第一層としてＳｒ−Ｏ原子層又はＣａ原子層の
いずれかを形成し、以下単位格子の整数倍を積み上げる
と最上層に伝導性Ｃｕ−Ｏ原子層が形成され、しかも薄
膜全体の電荷が中性化される。Further, the Bi system (22) having the crystal structure shown in FIG.
12) The oxide superconductor thin film of the composition
To (d), ha, d, b, i, i, b, d, c, d, b,
Open one by one for a predetermined time in the order of a, b, b and c to form Ca, Cu-O, Sr-O, B
i-O, Bi-O, Sr-O, Cu-O, Ca, Cu-
O, Sr-O, Bi-O, Bi-O, Sr-O, Cu-
Each atomic layer of O is sequentially stacked to form a unit cell;
This operation is repeated a plurality of times to form a Cu—O atomic layer on the uppermost layer, thereby manufacturing the semiconductor device. In the above, the Cu-O atomic layer formed on the uppermost layer is a conductive Cu-O atomic layer sandwiched between the Sr-O atomic layer and the Ca atomic layer appearing in the unit cell,
Forming either a Sr-O atomic layer or a Ca atomic layer as a first layer on a substrate, and stacking an integral multiple of the unit cell below, forms a conductive Cu-O atomic layer on the uppermost layer, and furthermore, the entire thin film The charge is neutralized.
【００１０】図２イ，ロに示したＴｌ2 Ｂａ2 Ｃａ2 Ｃ
ｕ3 ＯZ 組成又はＴｌ2 Ｂａ2 Ｃａ1 Ｃｕ2 ＯZ 組成の
酸化物超電導体の結晶の単位格子は、前述したように、
図１イ，ロに示したＢｉ系（２２２３）組成又はＢｉ系
（２２１２）組成のＢｉ及びＳｒをそれぞれＴｌ及びＢ
ａに代えたものであり、各々の原子層の積み上げ方法
は、Ｂｉ系酸化物超電導体の場合と同じ方法によりなさ
れる。この酸化物超電導体薄膜の場合は、基板面上の第
１層には、Ｂａ−Ｏ又はＣａ原子層を配置し、この上に
単位格子を整数倍積み上げると最上層に伝導性のＣｕ−
Ｏ原子層が位置する。図３に示した一般式ＬｎＢａ2 Ｃ
ｕ3 Ｏ7-x （式中ＬｎはＹ及びランタノイド金属元素の
中の１元素又は複数元素）で示される組成の酸化物超電
導体は、Ｂａ−Ｏ，ＣｕＯ鎖，Ｂａ−Ｏ，Ｃｕ−Ｏ，
Ｙ，Ｃｕ−Ｏ，Ｂａ−Ｏ，ＣｕＯ鎖，Ｂａ−Ｏ，Ｃｕ−
Ｏ，Ｙ，Ｃｕ−Ｏ，の各々の原子層を順次積み上げて形
成するものであって、この酸化物超電導体薄膜の場合
は、基板面上の第一層に、Ｂａ−Ｏ又はＹ原子層を配置
し、この上に単位格子を整数倍積み上げると最上層にＣ
ｕ−Ｏ原子層が位置し、且つ酸化物超電導体薄膜全体の
電荷が中性化される。The Tl 2 Ba 2 Ca 2 C shown in FIGS.
The unit cell of the crystal of the oxide superconductor having the u 3 O Z composition or the Tl 2 Ba 2 Ca 1 Cu 2 O Z composition is, as described above,
Bi and Sr of the Bi-based (2223) composition or Bi-based (2212) composition shown in FIGS.
The method of stacking each atomic layer is the same as that of the Bi-based oxide superconductor. In the case of this oxide superconductor thin film, a Ba—O or Ca atomic layer is arranged on the first layer on the substrate surface, and a unit cell is stacked thereon by an integral multiple to form a conductive Cu— layer on the uppermost layer.
The O atomic layer is located. The general formula LnBa 2 C shown in FIG.
An oxide superconductor having a composition represented by u 3 O 7-x (where Ln is one or more of Y and a lanthanoid metal element) is made of Ba—O, CuO chain, Ba—O, Cu—O ,
Y, Cu-O, Ba-O, CuO chain, Ba-O, Cu-
O, Y, and Cu—O are formed by sequentially stacking atomic layers. In the case of this oxide superconductor thin film, a Ba—O or Y atomic layer is formed on the first layer on the substrate surface. Is placed on top of this, and a unit cell is piled up on the whole by an integral number.
The u-O atomic layer is located, and the charge of the entire oxide superconductor thin film is neutralized.
【００１１】[0011]
【作用】本発明の酸化物超電導体薄膜は、Ｃｕを構成元
素とする酸化物超電導体を基板上にＣ軸配向させて形成
し、最上層に超電導状態に寄与する伝導性Ｃｕ−Ｏ原子
層を位置させたものなので、表面抵抗が小さい。The oxide superconductor thin film of the present invention is formed by forming an oxide superconductor containing Cu as a constituent element on a substrate with a C-axis orientation, and forming a conductive Cu—O atomic layer contributing to the superconducting state on the uppermost layer. Surface resistance is low.
【００１２】[0012]
【実施例】以下に本発明を実施例により詳細に説明す
る。 実施例１ 図４に示したＭＢＥ装置により、Ｂｉ系（２２２３）組
成の酸化物超電導体薄膜をＬａＡｌＯ3 単結晶基板の
（１００）面上に３０００Åの厚さに形成した。蒸発源
として、セルａ，ｂ，ｃ，ｄにＢｉ2 Ｏ3 ，Ｓｒ，Ｃ
ａ，Ｃｕをそれぞれ充填し、各々をヒーターにより８２
０℃，８００℃，８５０℃，１１００℃に加熱した。蒸
発速度は、各々の蒸発量を水晶振動式膜厚計により計測
し、計測結果をそれぞれのシャッター（イ）〜（ニ）に
連動して蒸発源毎に１〜５Å／ｓｅｃの範囲の所定の速
度になるように自動制御した。シャッター（イ）〜
（ニ）は、前述の通り、ハ，ニ，ハ，ニ，ロ，イ，イ，
ロ，ニ，ハ，ニ，ハ，ニ，ロ，イ，イ，ロ，ニの順序で
１個づつ開いてＣａ，ＣｕＯ鎖，Ｃａ，Ｃｕ−Ｏ，Ｓｒ
−Ｏ，Ｂｉ−Ｏ，Ｂｉ−Ｏ，Ｓｒ−Ｏ，Ｃｕ−Ｏ，Ｃ
ａ，ＣｕＯ鎖，Ｃａ，Ｃｕ−Ｏ，Ｓｒ−Ｏ，Ｂｉ−Ｏ，
Ｂｉ−Ｏ，Ｓｒ−Ｏ，Ｃｕ−Ｏの各々の原子層を１層づ
つ上記順序で繰返し積み上げて最上層にＣｕ−Ｏ層を形
成して、Ｂｉ系（２２２３）組成の酸化物超電導体薄膜
を製造した。 実施例２ 実施例１において、シャッター（イ）〜（ニ）を、ハ，
ニ，ロ，イ，イ，ロ，ニ，ハ，ニ，ロ，イ，イ，ロ，ニ
の順序で１個づつ所定時間開いてＣａ，Ｃｕ−Ｏ，Ｓｒ
−Ｏ，Ｂｉ−Ｏ，Ｂｉ−Ｏ，Ｓｒ−Ｏ，Ｃｕ−Ｏ，Ｃ
ａ，Ｃｕ−Ｏ，Ｓｒ−Ｏ，Ｂｉ−Ｏ，Ｂｉ−Ｏ，Ｓｒ−
Ｏ，Ｃｕ−Ｏの各々の原子層を上記順序で１層づつ繰返
し積み上げて最上層にＣｕ−Ｏ原子層を形成した他は、
実施例１と同じ方法によりＢｉ系（２２１２）組成の酸
化物超電導体薄膜を製造した。The present invention will be described below in detail with reference to examples. Example 1 A Bi-based (2223) composition oxide superconductor thin film was formed to a thickness of 3000 ° on a (100) plane of a LaAlO 3 single crystal substrate by the MBE apparatus shown in FIG. As the evaporation source, cells a, b, c, Bi 2 O 3 to d, Sr, C
a and Cu, respectively, and each was filled with 82
Heated to 0 ° C, 800 ° C, 850 ° C, 1100 ° C. The evaporation rate is measured by a quartz vibrating film thickness meter for each evaporation amount, and the measurement results are linked to the respective shutters (a) to (d) in a predetermined range of 1 to 5 ° / sec for each evaporation source. Automatically controlled to reach speed. Shutter (A) ~
(D) is, as described above, ha, ni, ha, ni, ro, i, i, i,
B, d, c, d, d, d, d, d, d, d are opened one by one in the order of Ca, CuO chain, Ca, Cu-O, Sr.
—O, Bi—O, Bi—O, Sr—O, Cu—O, C
a, CuO chain, Ca, Cu-O, Sr-O, Bi-O,
Each atomic layer of Bi-O, Sr-O, and Cu-O is repeatedly stacked one by one in the above order to form a Cu-O layer on the uppermost layer, and a Bi-based (2223) composition oxide superconductor thin film Was manufactured. Example 2 In Example 1, shutters (a) to (d) were replaced by
D, b, b, b, b, b, b, b, b, b, b, c are opened one by one in the order of Ca, Cu-O, Sr.
—O, Bi—O, Bi—O, Sr—O, Cu—O, C
a, Cu-O, Sr-O, Bi-O, Bi-O, Sr-
Except that each atomic layer of O and Cu-O was repeatedly stacked one by one in the above order to form a Cu-O atomic layer on the uppermost layer,
An oxide superconductor thin film having a Bi-based (2212) composition was manufactured in the same manner as in Example 1.
【００１３】実施例３ セルａ，ｂ，ｃ，ｄに蒸発源として、それぞれＴｌ2 Ｏ
3 ，Ｂａ，Ｃａ，Ｃｕを充填し、ヒーターによりそれぞ
れを７２０℃，７４０℃，８５０℃，１１００℃に加熱
し、前記セルの各々のシャッター（イ）〜（ニ）をハ，
ニ，ハ，ニ，ロ、イ，イ，ロ，ニ，ハ，ニ，ハ，ニ，
ロ，イ，イ，ロ，ニの順序で１個づつ所定時間開いてＣ
ａ，ＣｕＯ鎖，Ｃａ，Ｃｕ−Ｏ，Ｂａ−Ｏ，Ｔｌ−Ｏ，
Ｔｌ−Ｏ，Ｂａ−Ｏ，Ｃｕ−Ｏ，Ｃａ，ＣｕＯ鎖，Ｃ
ａ，Ｃｕ−Ｏ，Ｓｒ−Ｏ，Ｔｌ−Ｏ，Ｔｌ−Ｏ，Ｂａ−
Ｏ，Ｃｕ−Ｏの各々の原子層を上記順序で１層づつ繰返
し積み上げて最上層にＣｕ−Ｏ原子層を形成した他は、
実施例１と同じ方法によりＴｌ系（２２２３）組成の酸
化物超電導体薄膜を製造した。 実施例４ 実施例３において、シャッター（イ）〜（ニ）を、ハ，
ニ，ロ，イ，イ，ロ，ニ，ハ，ニ，ロ，イ，イ，ロ，ニ
の順序で１個づつ所定時間開いてＣａ，Ｃｕ−Ｏ，Ｂａ
−Ｏ，Ｔｌ−Ｏ，Ｔｌ−Ｏ，Ｂａ−Ｏ，Ｃｕ−Ｏ，Ｃ
ａ，Ｃｕ−Ｏ，Ｂａ−Ｏ，Ｂｉ−Ｏ，Ｂｉ−Ｏ，Ｂａ−
Ｏ，Ｃｕ−Ｏの各々の原子層を上記順序で１層づつ繰返
し積み上げて最上層にＣｕ−Ｏ層を形成した他は、実施
例３と同じ方法によりＴｌ系（２２１２）組成の酸化物
超電導体薄膜を製造した。 実施例５ セルａ，ｂにそれぞれＢａ，Ｃｕを充填し、各々の温度
を７４０℃，１１００℃に加熱した。又Ｙは蒸発温度が
高いので、セルｃの代わりにカーボン製るつぼを配置
し、この中にＹを充填し電子銃で１４５０℃に加熱し
た。上記のカーボン製るつぼのシャッターには、ハのシ
ャッターを用いた。かくして、それぞれのシャッター
（イ）〜（ハ）を、ハ，ロ，イ，ロ，イ，ロ，ハ，ロ，
イ，ロ，イ，ロの順序で１個づつ所定時間開いて、Ｙ，
Ｃｕ−Ｏ，Ｂａ−Ｏ，ＣｕＯ鎖，Ｂａ−Ｏ，Ｃｕ−Ｏ，
Ｙ，Ｃｕ−Ｏ，Ｂａ−Ｏ，ＣｕＯ鎖，Ｂａ−Ｏ，Ｃｕ−
Ｏの各々の原子層を上記順序で１層づつ積み上げて最上
層にＣｕ−Ｏ原子層を形成したＹＢａＣｕＯ系酸化物超
電導体薄膜を製造した。Embodiment 3 Tl 2 O was used as an evaporation source in cells a, b, c and d.
3 , Ba, Ca, and Cu were charged, and each was heated to 720 ° C., 740 ° C., 850 ° C., and 1100 ° C. by a heater, and shutters (a) to (d) of each of the cells were c and c.
Ni, ha, ni, ro, i, i, ro, ni, ha, ni, ha, ni,
Open one by one for a given time in the order of b, i, i, b, d
a, CuO chain, Ca, Cu-O, Ba-O, Tl-O,
Tl-O, Ba-O, Cu-O, Ca, CuO chain, C
a, Cu-O, Sr-O, Tl-O, Tl-O, Ba-
Except that each atomic layer of O and Cu-O was repeatedly stacked one by one in the above order to form a Cu-O atomic layer on the uppermost layer,
An oxide superconductor thin film having a Tl (2223) composition was produced in the same manner as in Example 1. Example 4 In Example 3, shutters (a) to (d) were replaced by
D, b, b, b, d, b, c, d, b, d are opened one by one in the order of Ca, Cu-O, Ba.
-O, Tl-O, Tl-O, Ba-O, Cu-O, C
a, Cu-O, Ba-O, Bi-O, Bi-O, Ba-
Oxide superconductivity of Tl (2212) composition was formed in the same manner as in Example 3 except that each atomic layer of O and Cu-O was repeatedly stacked one by one in the above order to form a Cu-O layer on the uppermost layer. A body thin film was manufactured. Example 5 Cells a and b were filled with Ba and Cu, respectively, and the respective temperatures were heated to 740 ° C. and 1100 ° C. Further, since Y has a high evaporation temperature, a carbon crucible was placed in place of cell c, Y was filled therein, and heated to 1450 ° C. with an electron gun. As the shutter of the above-mentioned carbon crucible, a shutter of Ha was used. Thus, each shutter (a) to (c) is called ha, ro, i, ro, i, ro, ha, ro,
Open one by one in the order of i, b, i, b
Cu-O, Ba-O, CuO chain, Ba-O, Cu-O,
Y, Cu-O, Ba-O, CuO chain, Ba-O, Cu-
Each atomic layer of O was stacked one by one in the above order to produce a YBaCuO-based oxide superconductor thin film having a Cu—O atomic layer formed on the uppermost layer.
【００１４】比較例１ 実施例１において、シャッター（イ）〜（ニ）を、ニ，
ハ，ニ，ハ，ニ，ロ，イ，イ，ロ，ニ，ハ，ニ，ハ，
ニ，ロ，イ，イ，ロの順序で１個づつ所定時間開く操作
を所要回数繰り返して最上層にＳｒ−Ｏ原子層を形成し
た他は、実施例１と同じ方法によりＢｉ系（２２２３）
組成の酸化物超電導体薄膜を製造した。 比較例２ 実施例２において、シャッター（イ）〜（ニ）を、ニ，
ハ，ニ，ロ，イ，イ，ロ，ニ，ハ，ニ，ロ，イ，イ，ロ
の順序で１個づつ所定時間開く操作を所要回数繰り返し
て最上層にＳｒ−Ｏ原子層を形成した他は、実施例２と
同じ方法によりＢｉ系（２２１２）組成の酸化物超電導
体薄膜を製造した。 比較例３ 実施例３において、シャッター（イ）〜（ニ）を、ニ，
ハ，ニ，ハ，ニ，ロ，イ，イ，ロ，ニ，ハ，ニ，ハ，
ニ，ロ，イ，イ，ロの順序で１個づつ所定時間開く操作
を所要回数繰り返して最上層にＢａ−Ｏ原子層を形成し
た他は、実施例３と同じ方法によりＴｌ系（２２２３）
組成の酸化物超電導体薄膜を製造した。Comparative Example 1 In Example 1, the shutters (a) to (d) were replaced with
Ha, ni, ha, ni, ro, i, i, ro, ni, ha, ni, ha,
The Bi system (2223) is formed in the same manner as in the first embodiment except that the operation of opening one by one for a predetermined time in the order of d, b, a, b, and b is repeated a required number of times to form an Sr-O atomic layer on the uppermost layer.
An oxide superconductor thin film having the composition was manufactured. Comparative Example 2 In Example 2, shutters (a) to (d) were replaced with
The operation of opening each one for a predetermined time in the order of c, d, b, b, d, b, d, c, d, b, d, a, b is repeated a required number of times to form an Sr-O atomic layer on the uppermost layer. Other than that, a Bi-based (2212) composition oxide superconductor thin film was manufactured in the same manner as in Example 2. Comparative Example 3 In Example 3, the shutters (a) to (d) were replaced with (d) and (d).
Ha, ni, ha, ni, ro, i, i, ro, ni, ha, ni, ha,
The Tl system (2223) is formed in the same manner as in the third embodiment except that the operation of opening one by one in the order of d, b, b, b, and b is repeated a required number of times to form a Ba-O atomic layer on the uppermost layer.
An oxide superconductor thin film having the composition was manufactured.
【００１５】比較例４ 実施例４において、シャッター（イ）〜（ニ）を、ニ，
ハ，ニ，ロ，イ，イ，ロ，ニ，ハ，ニ，ロ，イ，イ，ロ
の順序で１個づつ所定時間開く操作を所要回数繰り返し
て最上層にＢａ−Ｏ原子層を形成した他は、実施例４と
同じ方法によりＴｌ系（２２１２）組成の酸化物超電導
体薄膜を製造した。 比較例５ 実施例５において、シャッター（イ）〜（ニ）を、ロ，
ハ，ロ，イ，ロ，イ，ロ，ハ，ロ，イ，ロ，イの順序で
１個づつ所定時間開く操作を所要回数繰り返して最上層
にＢａ−Ｏ原子層を形成した他は、実施例５と同じ方法
によりＹＢａＣｕＯ系酸化物超電導体薄膜を製造した。
このようにして得られた各々の酸化物超電導体薄膜に
ついて、Ｔｃを４端子法により測定した。又液体窒素中
（７７Ｋ）にて、１０ＧＨｚのマイクロ波を照射した状
態で表面抵抗（Ｒs ）を測定した。結果は表１に示し
た。尚、各々の薄膜について、Ｘ線回折法により結晶配
向性を調べたところ、いずれもＣ軸配向していた。Comparative Example 4 In Example 4, shutters (a) to (d) were replaced with
The operation of opening one by one in the order of c, d, b, d, i, b, d, c, d, b, b, b, b is repeated a required number of times to form a Ba-O atomic layer on the uppermost layer. Except that, a Tl-based (2212) composition oxide superconductor thin film was manufactured in the same manner as in Example 4. Comparative Example 5 In Example 5, the shutters (a) to (d) were replaced by
Except that the operation of opening one by one for a predetermined number of times in the order of c, b, b, b, b, b, b, b, b, b, b, b, b, b, b, b In the same manner as in Example 5, a YBaCuO-based oxide superconductor thin film was manufactured.
For each of the oxide superconductor thin films thus obtained, Tc was measured by a four-terminal method. Further, the surface resistance (Rs) was measured in a state where microwaves of 10 GHz were irradiated in liquid nitrogen (77 K). The results are shown in Table 1. In addition, when the crystal orientation of each thin film was examined by an X-ray diffraction method, all of the thin films were C-axis oriented.
【００１６】[0016]
【表１】 [Table 1]
【００１７】表１より明らかなように、本発明例品（No
１〜５）はＴｃが高く、又表面抵抗が小さく、ミリ波・
マイクロ波デバイス用として優れた特性のものであっ
た。これは酸化物超電導体薄膜の最上層に伝導性のＣｕ
−Ｏ原子層が形成されている為である。これに対し、比
較例品（No６〜10）は、特に表面抵抗が大きい値のもの
となったが、これは酸化物超電導体薄膜の最上層に電気
を通し難いＳｒ−Ｏ原子層又はＢａ−Ｏ原子層が形成さ
れている為である。As is clear from Table 1, the sample of the present invention (No.
1-5) have high Tc, low surface resistance, and
It had excellent characteristics for microwave devices. This is because the conductive Cu
This is because the -O atomic layer is formed. On the other hand, the comparative example (Nos. 6 to 10) had a particularly large surface resistance, but this was due to the Sr—O atomic layer or Ba— This is because an O atomic layer is formed.
【００１８】[0018]
【効果】以上述べたように、本発明の酸化物超電導体薄
膜は、最上層に伝導性のＣｕ−Ｏ原子層が形成されてい
るので表面抵抗が小さく、依ってミリ波・マイクロ波デ
バイス等の薄膜導体として用いて、顕著な効果を奏す
る。As described above, the oxide superconductor thin film of the present invention has a low surface resistance since the conductive Cu—O atomic layer is formed on the uppermost layer, and therefore has a low resistance in millimeter-wave / microwave devices. It has a remarkable effect when used as a thin film conductor.
【図面の簡単な説明】[Brief description of the drawings]
【図１】ＢｉＳｒＣａＣｕＯ系酸化物超電導体の結晶の
単位格子の説明図である。FIG. 1 is an explanatory diagram of a unit cell of a crystal of a BiSrCaCuO-based oxide superconductor.
【図２】ＴｌＢａＣａＣｕＯ系酸化物超電導体の結晶の
単位格子の説明図である。FIG. 2 is an explanatory diagram of a unit cell of a crystal of a TlBaCaCuO-based oxide superconductor.
【図３】ＹＢａＣｕＯ系酸化物超電導体の結晶の単位格
子の説明図である。FIG. 3 is an explanatory diagram of a unit cell of a crystal of a YBaCuO-based oxide superconductor.
【図４】本発明の酸化物超電導体薄膜を製造するのに用
いる分子線エピタキシー装置の要部説明図である。FIG. 4 is an explanatory view of a main part of a molecular beam epitaxy apparatus used for producing the oxide superconductor thin film of the present invention.
１ チャンバー ２ 基板 ３，13 ヒーター ４ 水晶振動式膜厚計 ａ〜ｄ セル （イ）〜（ニ） シャッター DESCRIPTION OF SYMBOLS 1 Chamber 2 Substrate 3, 13 Heater 4 Quartz-vibration-type film thickness meter a-d cell (a)-(d) Shutter
フロントページの続き (56)参考文献 特開 平１−130420（ＪＰ，Ａ) 特開 平１−246371（ＪＰ，Ａ) 特開 平１−268865（ＪＰ，Ａ) 特開 平２−5581（ＪＰ，Ａ) 特開 平２−239104（ＪＰ，Ａ) 特開 平３−12323（ＪＰ，Ａ) 特開 平２−306508（ＪＰ，Ａ) 特開 平４−329878（ＪＰ，Ａ) 国際公開90／13517（ＷＯ，Ａ１) (58)調査した分野(Int.Cl.7，ＤＢ名) C30B 1/00 - 35/00 C01G 1/00 H01B 12/06 H01P 11/00 Continuation of front page (56) References JP-A-1-130420 (JP, A) JP-A-1-246371 (JP, A) JP-A-1-268865 (JP, A) JP-A-2-5581 (JP) JP-A-2-239104 (JP, A) JP-A-3-12323 (JP, A) JP-A-2-306508 (JP, A) JP-A-4-329878 (JP, A) International publication 90 / 13517 (WO, A1) (58) Fields investigated (Int. Cl. 7 , DB name) C30B 1/00-35/00 C01G 1/00 H01B 12/06 H01P 11/00
Claims (1)
して含有する酸化物超電導体薄膜であって、前記薄膜の
結晶のＣ軸が基板面の垂線方向に配向しており、且つ前
記薄膜の最上層に伝導性のＣｕ−Ｏ原子層が形成されて
いることを特徴とする酸化物超電導体薄膜。1. An oxide superconductor thin film formed on a substrate and containing Cu as a constituent element, wherein a C axis of a crystal of the thin film is oriented in a direction perpendicular to a substrate surface, and the thin film A conductive Cu—O atomic layer is formed on the uppermost layer of the oxide superconductor thin film.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3115350A JP3021764B2 (en) | 1991-04-18 | 1991-04-18 | Oxide superconductor thin film |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3115350A JP3021764B2 (en) | 1991-04-18 | 1991-04-18 | Oxide superconductor thin film |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04321577A JPH04321577A (en) | 1992-11-11 |
| JP3021764B2 true JP3021764B2 (en) | 2000-03-15 |
Family
ID=14660350
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3115350A Expired - Lifetime JP3021764B2 (en) | 1991-04-18 | 1991-04-18 | Oxide superconductor thin film |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3021764B2 (en) |
-
1991
- 1991-04-18 JP JP3115350A patent/JP3021764B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04321577A (en) | 1992-11-11 |
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