JPH0555651A - Manufacture of josephson device - Google Patents
Manufacture of josephson deviceInfo
- Publication number
- JPH0555651A JPH0555651A JP3240541A JP24054191A JPH0555651A JP H0555651 A JPH0555651 A JP H0555651A JP 3240541 A JP3240541 A JP 3240541A JP 24054191 A JP24054191 A JP 24054191A JP H0555651 A JPH0555651 A JP H0555651A
- Authority
- JP
- Japan
- Prior art keywords
- board
- film
- substrate
- plane
- josephson
- 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.)
- Pending
Links
Landscapes
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】この発明は超電導体に部分的に形
成される弱結合を利用したジョセフソン素子の製造方法
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a Josephson device utilizing weak coupling partially formed in a superconductor.
【0002】[0002]
【従来の技術】弱結合ジョセフソン素子として、ブリッ
ジ型ジョセフソン素子がある。図4は一般的なブリッジ
型ジョセフソン素子である。この素子は、超電導体薄膜
21に長さdのくびれ22を形成してその部分の超電導
性を弱め、弱結合にし、くびれのない部分に電圧端子2
3、24、電流端子25、26を設けたものである。く
びれ22の長さdは薄膜21の材料のコヒーレンス長程
度で、Nb、Pbなどの超電導体では数千Åである。2. Description of the Related Art As a weakly coupled Josephson element, there is a bridge type Josephson element. FIG. 4 shows a general bridge type Josephson device. In this device, a constriction 22 having a length d is formed in a superconductor thin film 21 to weaken the superconducting property of that portion and weakly couple it, and a voltage terminal 2 is formed in a portion without a constriction.
3, 24 and current terminals 25, 26 are provided. The length d of the constriction 22 is about the coherence length of the material of the thin film 21, and is several thousand Å in the case of a superconductor such as Nb or Pb.
【0003】ところで、高臨界温度超電導体として知ら
れているLn−Ba−Cu−O(Lnは希土類元素)は
コヒーレンス長がNb、Pbなどの1/100程度であ
り、通常の方法ではブリッジ型ジョセフソン素子の作成
は不可能である。しかし、このような酸化物超電導体で
は、一般的に膜成長時に粒成長を起こし、粒界が形成さ
れる。このため膜の内部の所々で弱結合、すなわち粒界
ジョセフソン結合が形成される。この弱結合のため、臨
界電流密度が大きくならないという問題があるが、この
粒界ジョセフソン結合を利用してさまざまな素子が試作
されている。By the way, Ln-Ba-Cu-O (Ln is a rare earth element) known as a high critical temperature superconductor has a coherence length of about 1/100 of Nb, Pb, etc. It is impossible to make a Josephson device. However, in such an oxide superconductor, grain growth generally occurs during film growth to form grain boundaries. Therefore, weak bonds, that is, grain boundary Josephson bonds, are formed in various places inside the film. There is a problem that the critical current density does not increase due to this weak coupling, but various devices have been prototyped using this grain boundary Josephson coupling.
【0004】図5はその例である。図5は、酸化物超電
導体、特にLn−Ba−Cu−Oを用いたSQUID
(超電導量子干渉計)で、ブリッジ型ジョセフソン素子
を二つ並列に接続したような素子であり、二つのくびれ
34をはさむ二つの部分33に電圧端子35、36、電
流端子37、38が設けられている。FIG. 5 shows an example. FIG. 5 is a SQUID using an oxide superconductor, particularly Ln-Ba-Cu-O.
(Superconducting quantum interferometer), which is an element in which two bridge type Josephson elements are connected in parallel, and voltage terminals 35 and 36 and current terminals 37 and 38 are provided in two portions 33 that sandwich two constrictions 34. Has been.
【0005】[0005]
【発明が解決しようとする課題】Ln−Ba−Cu−O
系の超電導体では、上述のように非常に弱結合ができや
すい。しかし、Ln−Ba−Cu−O系より10K以上
高い臨界温度をもつBi−Sr−Ca−Cu−O(BS
CCO)系あるいはBi−Pb−Sr−Ca−Cu−O
(BPSCCO)系超電導体では、膜成長時に粒成長が
起こすにもかかわらず、粒界ジョセフソン特性が観察さ
れない。[Problems to be Solved by the Invention] Ln-Ba-Cu-O
In the superconductor of the system, as described above, very weak coupling is likely to occur. However, Bi-Sr-Ca-Cu-O (BS with a critical temperature higher than 10 K higher than that of the Ln-Ba-Cu-O system
CCO) -based or Bi-Pb-Sr-Ca-Cu-O
In the (BPSCCO) based superconductor, grain boundary Josephson characteristics are not observed although grain growth occurs during film growth.
【0006】このため、図5に示すような素子はBSC
CO系ではつくられていない。また粒界ジョセフソン素
子でない図4に示すような素子を動作するには、コヒー
レンス長程度の微細加工が必要であるが、現在の技術で
は困難である。Therefore, the element shown in FIG.
It is not made with CO. Further, in order to operate an element as shown in FIG. 4 which is not a grain boundary Josephson element, fine processing of a coherence length is necessary, which is difficult with the current technology.
【0007】本発明の目的は、上述の問題を解決し、作
製容易なジョセフソン素子を提供することにある。An object of the present invention is to solve the above-mentioned problems and provide a Josephson device which is easy to manufacture.
【0008】[0008]
【課題を解決するための手段】この発明のジョセフソン
素子の製造方法は、MgO基板に種々の方位の面出しを
行うと共に、この基板に酸化物超電導薄膜を堆積するこ
とにより、酸化物超電導薄膜の成長方向依存性並びに基
板の角度により弱結合を形成することを特徴とする。According to the method for manufacturing a Josephson element of the present invention, the MgO substrate is chamfered in various orientations, and the oxide superconducting thin film is deposited on this substrate to form the oxide superconducting thin film. It is characterized in that weak bonds are formed depending on the growth direction dependence of the substrate and the angle of the substrate.
【0009】[0009]
【作用】MgO(100)面の上に堆積される酸化物超
電導薄膜はc軸が基板に垂直に成長する。また(10
0)面に45゜傾斜した面はMgO(110)面の方向
となり、その面に堆積される酸化物超電導薄膜はc軸に
平行に成長する。In the oxide superconducting thin film deposited on the MgO (100) surface, the c-axis grows perpendicular to the substrate. Also (10
The plane inclined at 45 ° to the (0) plane is in the direction of the MgO (110) plane, and the oxide superconducting thin film deposited on that plane grows parallel to the c-axis.
【0010】c軸が基板に垂直に成長した超電導薄膜は
膜面に平行に超電導電子対が流れ易いが、c軸が基板に
平行に成長した超電導薄膜は膜面に平行方向には超電導
電子対が流れにくくなる。In the superconducting thin film having the c-axis grown perpendicular to the substrate, the superconducting pair easily flows in parallel to the film surface, but in the superconducting thin film having the c-axis grown parallel to the substrate, the superconducting pair runs in the direction parallel to the film surface. Becomes difficult to flow.
【0011】従って、結晶方位の異なる面で一種の弱結
合型ジョセフソン接合を構成する。Therefore, a kind of weak-coupling Josephson junction is formed by planes having different crystal orientations.
【0012】また、結晶方位の異なる面の境界は基板に
角度がついており、この上に堆積される膜は粒界を形成
し、粒界効果型のジョセフソン接合も構成する。Further, the boundaries between the planes having different crystallographic orientations are angled to the substrate, and the film deposited thereon forms grain boundaries and also constitutes a grain boundary effect type Josephson junction.
【0013】[0013]
【実施例】以下、この発明の実施例について図面に従い
説明する。図1はこの発明の一実施例を示す断面図であ
る。Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the present invention.
【0014】基板10として、MgO基板を用いA面と
C面は(100)面を有する。そして、B面はA面に対
して45゜傾斜するように形成されており、このB面は
(110)面を有する。A MgO substrate is used as the substrate 10, and the A and C faces have a (100) face. The B surface is formed so as to be inclined by 45 ° with respect to the A surface, and the B surface has a (110) surface.
【0015】この基板10上に、ステップカバレージの
良好なCVD法により、YBCO膜、BSCCO膜等の
酸化物超電導薄膜11を積層形成する。An oxide superconducting thin film 11 such as a YBCO film or a BSCCO film is laminated on the substrate 10 by a CVD method having a good step coverage.
【0016】前述したように、基板10のA面及びC面
は(100)面を有するので、その上に堆積される酸化
膜超電導薄膜11はC軸が基板10に垂直に成長する。As described above, since the A-plane and C-plane of the substrate 10 have the (100) plane, the oxide superconducting thin film 11 deposited thereon grows with the C-axis perpendicular to the substrate 10.
【0017】また、基板10のB面は(110)面を有
するので、堆積される酸化物超電導薄膜11はC軸が基
板10に平行に成長する。Since the B-face of the substrate 10 has the (110) face, the C-axis of the deposited oxide superconducting thin film 11 grows parallel to the substrate 10.
【0018】従って、基板10のA、C面は図中a、b
面方向すなわち、膜面に平行に超電導電子対が流れ易
い。しかし、B面では超電導電子対は膜面に平行方向に
は流れにくく、A面→B面→C面で弱結合型のジョセフ
ソン接合を形成する。Therefore, the A and C planes of the substrate 10 are a and b in the figure.
The superconducting pair easily flows in the plane direction, that is, parallel to the film surface. However, in the B plane, the superconducting pair is unlikely to flow in the direction parallel to the film plane, and a weak coupling type Josephson junction is formed in the A plane → B plane → C plane.
【0019】更に、A面とB面、B面とC面の境界は、
基板10に角度がついているので、その上部に堆積され
る超電導薄膜11は粒界を形成する。従って、粒界効果
型のジョセフソン接合も堆積する。Further, the boundaries between the A and B surfaces and the B and C surfaces are
Since the substrate 10 is angled, the superconducting thin film 11 deposited on top of it forms grain boundaries. Therefore, a grain boundary effect type Josephson junction is also deposited.
【0020】図2及び図3は、部分的にブリッジ型接合
のくびれあるいは点接触型接合の接触部に相当する膜厚
の薄い部分を形成し、ジョセフソン接合を構成するため
に、基板に凹凸を形成する手法を示す工程図である。In FIGS. 2 and 3, a thin portion corresponding to the constriction of the bridge-type junction or the contact portion of the point contact type junction is partially formed to form a Josephson junction. FIG. 6 is a process drawing showing a method of forming a film.
【0021】この図2及び図3に従い弱結合型のジョセ
フソン素子の製造方法につき説明する。A method of manufacturing the weak coupling type Josephson device will be described with reference to FIGS.
【0022】まず基板として(100)面を有するMg
O基板40を用意する。First, Mg having a (100) plane as a substrate
An O substrate 40 is prepared.
【0023】図2(イ)に示すように、基板40に荷電
粒子ビーム60を照射する。このビーム60の照射領域
41が除去され、凹部42が形成される。As shown in FIG. 2A, the substrate 40 is irradiated with the charged particle beam 60. The irradiation region 41 of the beam 60 is removed, and the recess 42 is formed.
【0024】続いて、図2(ロ)に示すように、ビーム
径を絞って、基板40にビーム60を更に照射する。Subsequently, as shown in FIG. 2B, the beam diameter is narrowed and the substrate 40 is further irradiated with the beam 60.
【0025】図2(ハ)に示すように、このビーム60
の照射領域43が除去され凹部44が形成される。As shown in FIG. 2C, this beam 60
The irradiation region 43 is removed and a recess 44 is formed.
【0026】このように、ビーム径を徐々に絞り、基板
40にビーム60を照射することにより、図2(ニ)に
示すように、精密で連続した段差45が形成される。As described above, by gradually narrowing the beam diameter and irradiating the substrate 40 with the beam 60, a precise and continuous step 45 is formed as shown in FIG.
【0027】この段差45を形成したMgO基板40上
に、図3(イ)に示すように、YBCO、BSCCO等
の酸化物超電導薄膜50をスパッタリング法などにより
堆積する。As shown in FIG. 3A, an oxide superconducting thin film 50 of YBCO, BSCCO or the like is deposited on the MgO substrate 40 having the step 45 formed therein by a sputtering method or the like.
【0028】図3(ロ)に示すように、点線で囲んだ部
分に弱結合部が形成され、ジョセフソン接合素子が形成
される。As shown in FIG. 3B, a weak coupling portion is formed in a portion surrounded by a dotted line to form a Josephson junction element.
【0029】この方法によれば、弱結合部を直列に形成
することができ、この直列化により、インピーダンスの
向上が図れる。また、任意の数の直列化が可能である。According to this method, the weak coupling portion can be formed in series, and the serialization can improve the impedance. Also, any number of serializations is possible.
【0030】更に、弱結合間の距離が精密に制御でき直
列化による電圧標準利用や寸法を制御すれば、コヒーレ
ンス動作により、高インピーダンスの単一接合動作素子
ができる。Further, if the distance between the weak couplings can be precisely controlled and the voltage standard use and size are controlled by serialization, a high impedance single junction operating element can be formed by the coherence operation.
【0031】[0031]
【発明の効果】以上説明したように、この発明によれ
ば、結晶方位の異なる面で弱結合型ジョセフソン接合が
構成されると共に、結晶方位の異なる面の境界で粒界効
果型のジョセフソン接合が構成されるので、微細加工を
施す必要なく製造容易なジョセフソン接合素子を提供す
ることができる。As described above, according to the present invention, a weakly coupled Josephson junction is formed on the planes having different crystal orientations, and the grain boundary effect type Josephson junction is formed at the boundary between the planes having different crystal orientations. Since the junction is configured, it is possible to provide a Josephson junction element that can be easily manufactured without the need for performing fine processing.
【図1】この発明の実施例を示す断面図である。FIG. 1 is a sectional view showing an embodiment of the present invention.
【図2】基板に段差を形成し、弱結合型ジョセフソン素
子を構成する製造工程を示す断面図である。FIG. 2 is a cross-sectional view showing a manufacturing process in which a step is formed on a substrate to form a weakly coupled Josephson element.
【図3】基板に段差を形成し、弱結合型ジョセフソン素
子を構成する製造工程を示す断面図である。FIG. 3 is a cross-sectional view showing a manufacturing process in which a step is formed on a substrate to form a weakly coupled Josephson element.
【図4】ブリッジ型ジョセフソン素子を示す断面図であ
る。FIG. 4 is a cross-sectional view showing a bridge-type Josephson element.
【図5】酸化物超電導体を用いたSQIDの平面図であ
る。FIG. 5 is a plan view of an SQID using an oxide superconductor.
10 MgO基板 11 酸化物超電導体薄膜 10 MgO substrate 11 Oxide superconductor thin film
Claims (1)
と共に、この基板に酸化物超電導薄膜を堆積することに
より、酸化物超電導薄膜の成長方向依存性並びに基板の
角度により弱結合を形成することを特徴とするジョセフ
ソン素子の製造方法。1. A MgO substrate is faced in various orientations and an oxide superconducting thin film is deposited on this substrate to form weak bonds depending on the growth direction dependence of the oxide superconducting thin film and the angle of the substrate. A method of manufacturing a Josephson device, characterized in that
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP3240541A JPH0555651A (en) | 1991-08-26 | 1991-08-26 | Manufacture of josephson device |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP3240541A JPH0555651A (en) | 1991-08-26 | 1991-08-26 | Manufacture of josephson device |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH0555651A true JPH0555651A (en) | 1993-03-05 |
Family
ID=17061070
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP3240541A Pending JPH0555651A (en) | 1991-08-26 | 1991-08-26 | Manufacture of josephson device |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH0555651A (en) |
-
1991
- 1991-08-26 JP JP3240541A patent/JPH0555651A/en active Pending
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP2798361B2 (en) | Superconducting field effect device having grain boundary channel and method of manufacturing the same | |
US5750474A (en) | Method for manufacturing a superconductor-insulator-superconductor Josephson tunnel junction | |
JPH05160449A (en) | Josephson junction structure | |
US5439875A (en) | Process for preparing Josephson junction device having weak link of artificial grain boundary | |
JPH098368A (en) | High temperature superconducting jesephson element and fabrication thereof | |
JP3568547B2 (en) | Josephson junction structure | |
JP2871516B2 (en) | Oxide superconducting thin film device | |
JPH0555651A (en) | Manufacture of josephson device | |
JP3189403B2 (en) | Element having superconducting junction and method of manufacturing the same | |
JPS6065583A (en) | Josephson junction element and manufacture thereof | |
JP2994183B2 (en) | Superconducting element and manufacturing method thereof | |
JP2761504B2 (en) | Oxide superconducting device and manufacturing method thereof | |
JPH0272685A (en) | Method for forming weakly coupled superconductor part | |
JPH04268774A (en) | Josephson junction | |
JP2976851B2 (en) | Circuit manufacturing method using superconducting thin film | |
JPH0563247A (en) | Superconducting joint structure and production thereof | |
JPH10294499A (en) | Squid and manufacture therefor | |
JPH04293279A (en) | Manufacture of oxide superconducting film | |
JP2731513B2 (en) | Superconducting element and method of manufacturing the same | |
JPH0336771A (en) | Weak coupling type josephson junction element | |
JPH03211777A (en) | Structure and manufacture of josephson junction | |
JPH0432276A (en) | Josephson junction element | |
JPH04147681A (en) | Supedconducting junction | |
JPH06132577A (en) | Formation of oxide suprconducting josephson element | |
JPH05251769A (en) | Connection structure of superconducting current path |