JP2544390B2 - Oxide superconducting integrated circuit - Google Patents
Oxide superconducting integrated circuitInfo
- Publication number
- JP2544390B2 JP2544390B2 JP62165324A JP16532487A JP2544390B2 JP 2544390 B2 JP2544390 B2 JP 2544390B2 JP 62165324 A JP62165324 A JP 62165324A JP 16532487 A JP16532487 A JP 16532487A JP 2544390 B2 JP2544390 B2 JP 2544390B2
- Authority
- JP
- Japan
- Prior art keywords
- film
- oxide superconducting
- thin film
- srtio
- integrated circuit
- 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
- 239000010408 film Substances 0.000 claims description 100
- 239000010409 thin film Substances 0.000 claims description 33
- 229910002367 SrTiO Inorganic materials 0.000 claims description 17
- 239000011229 interlayer Substances 0.000 claims description 17
- 230000001681 protective effect Effects 0.000 claims description 8
- 239000002887 superconductor Substances 0.000 claims description 7
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 5
- 229910010413 TiO 2 Inorganic materials 0.000 claims description 4
- 238000009413 insulation Methods 0.000 claims 1
- 238000010030 laminating Methods 0.000 claims 1
- 239000010949 copper Substances 0.000 description 24
- 238000000034 method Methods 0.000 description 17
- 238000010438 heat treatment Methods 0.000 description 12
- 239000000463 material Substances 0.000 description 12
- 239000000758 substrate Substances 0.000 description 11
- 239000010410 layer Substances 0.000 description 10
- 229910052760 oxygen Inorganic materials 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 230000004888 barrier function Effects 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000003507 refrigerant Substances 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 238000004544 sputter deposition Methods 0.000 description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- 229910002480 Cu-O Inorganic materials 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 230000008034 disappearance Effects 0.000 description 2
- 239000012212 insulator Substances 0.000 description 2
- 238000001755 magnetron sputter deposition Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 238000001259 photo etching Methods 0.000 description 2
- 238000005477 sputtering target Methods 0.000 description 2
- 229910001020 Au alloy Inorganic materials 0.000 description 1
- 229910001152 Bi alloy Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910015617 MoNx Inorganic materials 0.000 description 1
- 229910009203 Y-Ba-Cu-O Inorganic materials 0.000 description 1
- 229910001297 Zn alloy Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910021417 amorphous silicon Inorganic materials 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000003486 chemical etching Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000001312 dry etching Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 238000010849 ion bombardment Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 238000001020 plasma etching Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 230000007261 regionalization Effects 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000001947 vapour-phase growth Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N60/00—Superconducting devices
- H10N60/10—Junction-based devices
- H10N60/12—Josephson-effect devices
- H10N60/124—Josephson-effect devices comprising high-Tc ceramic materials
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
- Containers, Films, And Cooling For Superconductive Devices (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、酸化物超電導体薄膜集積回路に係り、電極
膜の電気的絶縁、機械的保護及び腐食・反応防止を目的
とした絶縁膜に関する。Description: TECHNICAL FIELD The present invention relates to an oxide superconductor thin film integrated circuit, and relates to an insulating film for the purpose of electrical insulation, mechanical protection, and corrosion / reaction prevention of an electrode film. .
トンネル型ジョセフソン接合素子は、２つの超電導薄
膜の間に極めて薄いトンネル障壁層を挾んでサンドイッ
チ構造で、極低温（4.2K）における超電導トンネル現象
を応用したスイッチング素子である。この素子は、従来
の半導体素子に比べスイッチング速度は約１桁早いと同
時に、消費電力は約３桁小さいという特長があり、将来
の超高速計算機用の論理演算素子、記憶素子として期待
されている。それらの素子を構成するための超電導薄膜
には、おもにPb−In−Au合金、Pb−Bi合金、Nb及びNbN
などが用いられている。また抵抗薄膜にはAu−Zn合金、
Mo、あるいはMoNxなどが用いられている。さらに上記超
電導薄膜、抵抗体薄膜の相互電気的に絶縁するための層
間絶縁膜にはSiO膜、またはSiO2膜が用いられている。The tunnel-type Josephson junction element is a switching element that applies a superconducting tunnel phenomenon at extremely low temperature (4.2K) with a sandwich structure sandwiching an extremely thin tunnel barrier layer between two superconducting thin films. This element has a feature that the switching speed is about one order of magnitude faster than the conventional semiconductor element and the power consumption is about three orders of magnitude lower, and is expected as a logic operation element and a storage element for a future ultra-high-speed computer. . Superconducting thin films for constituting these elements mainly include Pb-In-Au alloy, Pb-Bi alloy, Nb and NbN.
Are used. The resistive thin film is made of Au-Zn alloy,
Mo or MoNx is used. Further, an SiO film or a SiO 2 film is used as an interlayer insulating film for mutually electrically insulating the superconducting thin film and the resistor thin film.
ところで、ジョセフソン接合素子は、従来液体ヘリウ
ムを冷媒として極低温冷却（〜4.2K）しながら所望の特
性を出現させていた。しかし最近希土類元素と銅の複合
酸化物からなる層状のペロブスカイト類似構造が，従来
の金属系超電導材料に比べ著しく高い超電導臨界温度を
示すことがシアイツシュリフト フュール フィジィ
ク，ビー，コンデンスト マター,64号（1986年）189頁
（Zeitschrift fur Physik,B−Condensed Matter,64（1
986）189.）において論じられている。その後の研究に
よって、La−Sr−Cu−Ｏ系材料ではおよぞ30〜40Kで、
またＹ−Ba−Cu−Ｏ系材料では88Kで超電導性を示し抵
抗ゼロを示すことが明らかになった。それらの酸化物超
電導材料は酸化物ないし炭酸塩を用い、これを混合後90
0℃前後の高温で反応させ、さらに混合粉砕の後900℃〜
1000℃で熱処理することにより作製することができる。
また上述の酸化物超電導材料を薄膜にするには、高温熱
処理によって作製した焼結体をターゲットとしたスパッ
タリング成膜法が用いられる。このように作製した薄膜
を900℃前後の高温酸素雰囲気中で当処理することによ
り、前述した高臨界温度特性を示す膜が得られる。この
ような酸化物超電導材料の出現によって、これまで不可
能であった液体窒素冷媒を用いて動作するジョセフソン
接合素子の作製が可能になった。By the way, the Josephson junction element has conventionally exhibited desired characteristics while being cryogenically cooled (up to 4.2 K) using liquid helium as a coolant. Recently, however, a layered perovskite-like structure composed of a complex oxide of rare earth elements and copper exhibits a significantly higher superconducting critical temperature than conventional metal-based superconducting materials. Issue (1986) p. 189 (Zeitschrift fur Physik, B-Condensed Matter, 64 (1
986) 189.). Subsequent studies have shown that the La-Sr-Cu-O-based materials have a total temperature of 30-40K.
Further, it was revealed that the Y-Ba-Cu-O-based material exhibits superconductivity at 88K and zero resistance. As oxide superconducting materials, oxides or carbonates are used.
React at a high temperature around 0 ℃, and after mixing and crushing 900 ℃ 〜
It can be produced by heat treatment at 1000 ° C.
In order to make the above-mentioned oxide superconducting material into a thin film, a sputtering film forming method using a sintered body produced by a high-temperature heat treatment as a target is used. By subjecting the thus-produced thin film to a high temperature oxygen atmosphere at about 900 ° C., a film exhibiting the above-mentioned high critical temperature characteristic can be obtained. With the advent of such oxide superconducting materials, it has become possible to fabricate Josephson junction devices that operate using liquid nitrogen refrigerant, which has been impossible until now.
以上のような方法によって形成される酸化物超電導ジ
ョセフソン接合素子を主要素子として、論理演算回路、
記憶回路の集積回路を作製する場合電極膜をはじめ、抵
抗、インダクタ、キャパシタ等の薄膜部品を同一チップ
内に形成する必要があり、それらは一般に積層した構造
で実現している。そのため薄膜部品を相互に電気的に隔
離する必要があり、それを目的とした層間絶縁膜を用い
ている。通常も半導体では、そのような層間絶縁膜とし
てSiO2,SiO,Si3N4,Si又はアモルファスSi,Al2O3膜等が
用いられている。しかしそれらの膜を前述の酸化物超電
導薄膜の絶縁膜として用いた場合、前述した酸化物超電
導薄膜の高温、酸素中熱処理によって前記酸化物超電導
薄膜と絶縁膜中のSi元素と反応している超電導特性、例
えば超電導臨界温度Tcの低下もしくは超電導特性の消失
などが生じる。一方酸化物超電導薄膜は900℃前後の熱
処理を行うと、薄膜の表面からCu元素が析出し、組成の
ずれが生じること、さらには析出したCu元素が酸化し2C
u2Oが形成されｐ型の半導体的な性質を示すようにな
る。したがってCuの析出を完全に抑制することが超電導
薄膜の特性劣化を防ぐうえで特に重要になる。つまり前
述の熱処理に対して超電導電極材料の特性に影響を及ぶ
ことがないようにすることが必須条件である。With the oxide superconducting Josephson junction element formed by the above method as a main element, a logical operation circuit,
When manufacturing an integrated circuit of a memory circuit, it is necessary to form electrode films, thin film components such as resistors, inductors, and capacitors in the same chip, and these are generally realized by a laminated structure. Therefore, it is necessary to electrically isolate the thin film components from each other, and an interlayer insulating film is used for that purpose. Usually, in semiconductors, SiO 2 , SiO, Si 3 N 4 , Si or amorphous Si, Al 2 O 3 film is used as such an interlayer insulating film. However, when these films are used as the insulating film of the above-mentioned oxide superconducting thin film, the superconducting substance reacting with the Si element in the oxide superconducting thin film and the insulating film by the heat treatment of the above-mentioned oxide superconducting thin film at high temperature in oxygen. For example, a decrease in the superconducting critical temperature Tc or the disappearance of the superconducting property occurs. On the other hand, when an oxide superconducting thin film is subjected to heat treatment at about 900 ° C, Cu element precipitates from the surface of the thin film, causing a composition shift, and further, the precipitated Cu element oxidizes and 2C
u 2 O is formed and the p-type semiconductor property is exhibited. Therefore, it is especially important to completely suppress the precipitation of Cu in order to prevent the characteristic deterioration of the superconducting thin film. In other words, it is an essential condition that the above heat treatment does not affect the characteristics of the superconducting electrode material.
さらに前記YBa2Cu3O7-XをはじめとするTBa系ペロブス
カイト構造酸化物超電導材，ならびにSuBa2Cu3O7-Xをは
じめとするSrBa系ペロブスカイト構造酸化物超電導材は
いずれも水用と反応するため、液体冷媒を用いて冷却を
繰返し行うと大気中の水分を露結させて前記超電導体表
面層より水分が浸み込み、やがて超電導特性が変化し、
Tcの低下ないし超電導特性が消失するという問題があ
る。したがってそのような特性の経時変化、あるいは劣
化を防ぐために、酸化物超電導体が水用と反応すること
がないように保護膜を設け、耐湿性を向上させることが
極めて重要である。また、特願昭58−202815号公報に
は、酸化物超電導体薄膜と基板との間に、酸化物である
SrTiO3,BaTiO3、KTaO3、（Sr,Ba）TiO3、（Ca,Sr）TiO3
またはMgOを設けることにより、従来と比較して結晶性
の良い酸化物超電導体薄膜を成長する方法が記載されて
いる。Furthermore, the TBa-based perovskite structure oxide superconducting materials such as YBa 2 Cu 3 O 7-X and the SrBa-based perovskite structure oxide superconducting materials such as SuBa 2 Cu 3 O 7-X are both for water. Because of the reaction, when cooling is repeatedly performed using a liquid refrigerant, moisture in the atmosphere is condensed to infiltrate the moisture from the superconductor surface layer, and eventually the superconducting characteristics change,
There is a problem that Tc is lowered or superconductivity is lost. Therefore, in order to prevent such changes in characteristics over time or deterioration, it is extremely important to provide a protective film so as to prevent the oxide superconductor from reacting with water and improve the moisture resistance. Further, Japanese Patent Application No. 58-202815 discloses that an oxide is present between the oxide superconductor thin film and the substrate.
SrTiO 3 , BaTiO 3 , KTaO 3 , (Sr, Ba) TiO 3 , (Ca, Sr) TiO 3
Alternatively, a method of growing an oxide superconductor thin film having better crystallinity as compared with the prior art by providing MgO is described.
このように従来技術は酸化物超電導薄膜と層間絶縁物
との反応及び耐水性については配慮されておらず高温酸
化物超電導薄膜デバイスの開発に問題があった。As described above, the prior art does not consider the reaction between the oxide superconducting thin film and the interlayer insulator and the water resistance, and has a problem in developing a high temperature oxide superconducting thin film device.
本発明の目的は高温・熱処理に対しても安定でしかも
耐湿性にも優れた絶縁膜（保護膜も含む）を有した酸化
物超電導集積回路を提供することにある。An object of the present invention is to provide an oxide superconducting integrated circuit having an insulating film (including a protective film) which is stable to high temperature and heat treatment and has excellent moisture resistance.
上記目的は、SrTiO3膜をはじめTiO2、Ti2O5、TiC、Ti
NおよびTiB2を層間絶縁膜ならびに保護膜として用いる
ことにより達成される。The above objectives include SrTiO 3 film, TiO 2 , Ti 2 O 5 , TiC and Ti.
It is achieved by using N and TiB 2 as an interlayer insulating film and a protective film.
SrTiO3は融点が高く絶縁性に優れた誘電体結晶の一種
であり、高温酸化物超電導体物質の代表的なYBa2Cu3O
7-Xと結晶格子のａ軸、ｂ軸の格子定数がほぼ等しいた
め、SrTiO3を基板としてYBa2Cu3O7-Xを薄膜状に堆積し
た場合ｃ軸配向の強い薄膜が得られる。このようにSrTi
O3とYBa2Cu3O7-Xとの間では相互に結晶成長の整合性が
極めて良く薄膜の積層構造を形成するのに適している。
一方前述とは逆にYBa2Cu3O7-X膜上にSrTiO3膜を形成し
た場合はYBa2Cu3O7膜の層間絶縁膜としての役割を持た
せることができる。つまり前述した高温、酸素雰囲気中
における熱処理に対しても相互拡散が生じることがな
く、熱的に安定な積層膜を形成することができ、SrTiO3
膜は酸化物超電導薄膜を用いた集積回路素子の層間絶縁
物薄膜として、また水分に対する征護膜として十分に用
いることが可能である。SrTiO 3 is a type of dielectric crystal that has a high melting point and excellent insulating properties, and is typical of YBa 2 Cu 3 O, which is a typical high temperature oxide superconductor material.
Since 7-X and the lattice constants of the a-axis and the b-axis of the crystal lattice are almost equal to each other, when YBa 2 Cu 3 O 7-X is deposited in a thin film form using SrTiO 3 as a substrate, a thin film having a strong c-axis orientation can be obtained. Thus SrTi
O 3 and YBa 2 Cu 3 O 7-X have very good crystal growth matching with each other and are suitable for forming a thin film laminated structure.
On the other hand, contrary to the above, when the SrTiO 3 film is formed on the YBa 2 Cu 3 O 7-X film, the YBa 2 Cu 3 O 7 film can serve as an interlayer insulating film. That is, mutual diffusion does not occur even with the heat treatment in the above-mentioned high temperature and oxygen atmosphere, and a thermally stable laminated film can be formed, and SrTiO 3
The film can be sufficiently used as an interlayer insulator thin film of an integrated circuit device using an oxide superconducting thin film and as a moisture protective film.
以下、本発明の一実施例を第１図により説明する。Sr
TiO3絶縁性基板１の主表面上にＹ−Cu−ＯおよびBa−Cu
−Ｏ材からなる２枚のスパッタターゲットとするマグネ
ットロンスパッタ法によりYBa2Cu3O7-X膜を約１μｍの
厚さに堆積する。その際放電ガスの雰囲気は、Ar又はAr
＋10％O2の低圧力中であればどちらの雰囲気を選んでも
良い。なお基板材料には前述のSrTiO3の他にMgO,YSZの
いずれを用いても良い。基板温度は常温である。その後
酸素加圧雰囲気中で920℃−2hrの熱処理を行いYBa2Cu3O
7-X膜を結晶化させる。An embodiment of the present invention will be described below with reference to FIG. Sr
Y-Cu-O and Ba-Cu are formed on the main surface of the TiO 3 insulating substrate 1.
A YBa 2 Cu 3 O 7-X film is deposited to a thickness of about 1 μm by a magnetron sputtering method using two sputtering targets made of —O material. At that time, the atmosphere of the discharge gas is Ar or Ar.
Either atmosphere may be selected as long as it is under a low pressure of + 10% O 2 . Any of MgO and YSZ may be used as the substrate material in addition to SrTiO 3 described above. The substrate temperature is normal temperature. After that, heat treatment is performed at 920 ° C for 2 hours in an oxygen-pressurized atmosphere to perform YBa 2 Cu 3 O.
Crystallize the 7-X film.
つぎにYBa2Cu3O7-X膜にAZレジストを用いたフォトエ
ッチングプロセスの露光・現象処理により所望のレジス
トパターンを形成する。ついで前記レジストパターンマ
スクにして５％NHO3水溶液（容量％）でYBa2Cu3O7-X膜
をエッチングして所望のパターン形状とし、下部電極膜
２を形成する。なお本実施例ではYBa2Cu3O7-X膜のパタ
ーン形成は前記化学エッチング法のほかにAr等のイオン
衝撃によるドライエッチング法によっても良い。Next, a desired resist pattern is formed on the YBa 2 Cu 3 O 7-X film by exposure / phenomenon treatment in a photoetching process using an AZ resist. Then, the YBa 2 Cu 3 O 7-X film is etched with a 5% NHO 3 aqueous solution (volume%) using the resist pattern mask to form a desired pattern shape, and the lower electrode film 2 is formed. In the present embodiment, the pattern formation of the YBa 2 Cu 3 O 7-X film may be performed by the dry etching method by ion bombardment of Ar or the like in addition to the chemical etching method.
つぎに前記下部電極膜２上に層間絶縁膜となるSrTiO3
を堆積させる。SrTiO3の膜厚は1.8μｍで、SrTiO3焼結
体をスパッタ・ターゲットに用いたマグネトロンスパッ
タ法によって所望の膜厚の絶縁膜を基板の主面上全面に
形成する。堆積条件の一例は次のようである。Ar＋10％
O2混合を用い、ガスの圧力は10mTorr,放電電圧は1KV
で、膜の堆積速度は約16nm/分である。ついてSrTiO3膜
を形成した基板１の主面上にAZレジストを塗布し、熱硬
化処理を行ったうえ所望のフォトマスクを用いて露光、
現像処理を行ってレジストパターンを形成する。ついで
フレオンガスを主成分とするプラズマエッチング法によ
って前記SrTiO3膜を所望のパターンに形成し、その後レ
ジストを除去し、層間絶縁膜３を形成する。なおその際
に下部電極膜２の一部が露出するように開口部４を設け
る。つぎにArのプラズマ放電法により層間絶縁膜の開口
部より露出したYBa2Cu3O7-X膜表面をクリーニングす
る。クリーニング条件はAr圧力10mTorr、rf放電電圧800
V、放電時間は20分である。その後引き続いて上部電極
になるYBa2Cu3O7-X膜をスパッタ法により形成する。堆
積したYBa2Cu3O7-X膜の厚さは３μｍである。つぎに前
記各々の薄膜を積層した基板１を加圧酸素雰囲気中にお
いて900℃−2hrの熱処理を行い、さらに100℃/hの速度
で徐冷する。この熱処理の際に前記基板１の主面が、焼
結法で作製したYBa2Cu3O7-Xペレット面に直接接触する
ように載置する。この熱処理工程によって下部電極膜３
表面に形成された高抵抗層（組成のずれ、あるいは結晶
の乱れなどによって絶縁性の膜として存在）は、一部低
抵抗層に変化し、残るわずかな高抵抗層がトンネル障壁
層としての役割を果たすようになる。以上の熱処理を行
った後、YBa2Cu3O7-X膜をフォトエッチングプロセスに
より所望のパターンに加工し、上部電極５を形成する。Next, SrTiO 3 to be an interlayer insulating film is formed on the lower electrode film 2.
Deposit. The film thickness of SrTiO 3 is 1.8 μm, and an insulating film having a desired film thickness is formed on the entire main surface of the substrate by a magnetron sputtering method using a SrTiO 3 sintered body as a sputtering target. An example of deposition conditions is as follows. Ar + 10%
Using O 2 mixture, gas pressure is 10 mTorr, discharge voltage is 1 KV
At that, the deposition rate of the film is about 16 nm / min. Then, an AZ resist is applied on the main surface of the substrate 1 on which the SrTiO 3 film is formed, heat-treated, and exposed using a desired photomask,
Development processing is performed to form a resist pattern. Then, the SrTiO 3 film is formed into a desired pattern by a plasma etching method containing freon gas as a main component, and then the resist is removed to form an interlayer insulating film 3. At that time, the opening 4 is provided so that a part of the lower electrode film 2 is exposed. Next, the surface of the YBa 2 Cu 3 O 7-X film exposed through the opening of the interlayer insulating film is cleaned by Ar plasma discharge method. Cleaning conditions are Ar pressure 10mTorr, rf discharge voltage 800
V, discharge time is 20 minutes. After that, subsequently, a YBa 2 Cu 3 O 7-X film to be the upper electrode is formed by the sputtering method. The thickness of the deposited YBa 2 Cu 3 O 7-X film is 3 μm. Next, the substrate 1 on which each thin film is laminated is heat-treated at 900 ° C. for 2 hours in a pressurized oxygen atmosphere, and then gradually cooled at a rate of 100 ° C./h. At the time of this heat treatment, the substrate 1 is placed so that the main surface of the substrate 1 is in direct contact with the surface of the YBa 2 Cu 3 O 7 -X pellets produced by the sintering method. Through this heat treatment process, the lower electrode film 3
The high resistance layer formed on the surface (existing as an insulating film due to composition shift or crystal disorder) partially changes to a low resistance layer, and the remaining small high resistance layer functions as a tunnel barrier layer. Will be fulfilled. After performing the above heat treatment, the YBa 2 Cu 3 O 7-X film is processed into a desired pattern by a photoetching process to form the upper electrode 5.
以上の方法により、酸化物超電導薄膜を用いたジョセ
フソン集積回路を作製できる。このようにして作製され
た素子の代表的な接合特性は、Jc＝3000A/cm2、Rj/Rnn
＝８を示す。By the above method, a Josephson integrated circuit using an oxide superconducting thin film can be manufactured. Typical junction characteristics of the device fabricated in this way are Jc = 3000A / cm 2 , Rj / Rnn
= 8 is shown.
前記実施例のほかに、トンネル障壁層の形成法として
層間絶縁膜３の開口部４によって露出したYBa2Cu3O7-X
下部電極膜２の表面をAr減圧下のrf放電により清浄化す
るとともに、下部電極表面に存在する高抵抗層を完全に
除去したのち、Alを約Å堆積し、さらに熱酸化処理を行
い前記AlをAl2O3に改質したうえ、上部電極膜のYBa2Cu3
O7-X膜を形成し、トンネル接合を作製する。この場合も
前述の結果と同様の超電導特性が得られている。In addition to the above-mentioned embodiment, YBa 2 Cu 3 O 7-X exposed through the opening 4 of the interlayer insulating film 3 is used as a method of forming the tunnel barrier layer.
The surface of the lower electrode film 2 is cleaned by rf discharge under reduced pressure of Ar, and after removing the high resistance layer existing on the surface of the lower electrode completely, Al is deposited about Å, and further thermal oxidation treatment is performed to remove Al. Was modified to Al 2 O 3 and YBa 2 Cu 3 of the upper electrode film was
An O 7-X film is formed and a tunnel junction is prepared. Also in this case, the superconducting characteristics similar to the above-mentioned results are obtained.
さらにトンネル障壁層材料として５〜20ÅのMgO、SrT
iO3、ZrO2のいずれかを清浄化処理した下部電極表面に
堆積して接合を形成した場合も，前述と同様の超電導特
性が得られる。その場合，接合電流密度Jcは，各々のト
ンネル障壁層の膜厚に依存して変化する。In addition, 5 to 20Å MgO and SrT as tunnel barrier layer materials
The same superconducting characteristics as described above can be obtained when either iO 3 or ZrO 2 is deposited on the cleaned lower electrode surface to form a junction. In that case, the junction current density Jc changes depending on the film thickness of each tunnel barrier layer.
以上実施例では層絶縁膜としてSrTiO3膜を用いた場合
について述べたが、絶縁膜材料としてTiO2膜、Ti2O膜、
TiC膜、TiN膜およびTiB2を各々用いた場合についても、
前記実施例と同様の結果が得られる。In the above examples, the case where the SrTiO 3 film was used as the layer insulating film was described, but the TiO 2 film, the Ti 2 O film, and the
Also when using TiC film, TiN film and TiB 2 respectively,
The same result as in the above-mentioned embodiment is obtained.
さらにSrTiO3膜、Ti2O膜、Ti2O5膜、TiC膜、TiN膜お
よびTiB2膜の絶縁膜を２つないしはそれ以上を含む薄膜
を組合せて層間絶縁膜として用いた場合についても前記
実施例の場合と同様の結果が得られる。Furthermore, when using a thin film including two or more insulating films such as SrTiO 3 film, Ti 2 O film, Ti 2 O 5 film, TiC film, TiN film and TiB 2 film as an interlayer insulating film, The same result as in the above-mentioned embodiment is obtained.
なお、前記実施例における絶縁膜形成はスパッタ成膜
法によったが、気相成長法によっても良い。Although the insulating film is formed by the sputtering film forming method in the above embodiment, it may be formed by the vapor phase growth method.
以上述べたように本発明によれば、SrTiO3膜、Ti2O
膜、Ti2O5膜、TiC膜、TiN膜あるいはTiB2の薄膜を酸化
物超電導薄膜電極のための層間絶縁膜あるいは保護膜と
して用いることにより、従来問題になっていた高温、酸
素雰囲気中の熱処理を行った後の超電導特性の劣化、あ
るいは消滅は発生せず、また液体窒素冷媒中浸漬の繰返
しによる水用の浸入も防ぐことができ酸化物超電導電極
膜の腐食による本質を完全に防止することができる。As described above, according to the present invention, SrTiO 3 film, Ti 2 O
By using a film, Ti 2 O 5 film, TiC film, TiN film or TiB 2 thin film as an interlayer insulating film or protective film for oxide superconducting thin film electrodes, high temperature and oxygen atmosphere Degradation or disappearance of superconducting properties after heat treatment does not occur, and penetration of water due to repeated immersion in liquid nitrogen refrigerant can be prevented, and the essence of corrosion of oxide superconducting electrode film is completely prevented. be able to.
以上のように本発明により素子の安定性は著しく向上
する。As described above, the stability of the device is remarkably improved by the present invention.
第１図は本発明の一実施例の構成を示す断面図である。 符号の説明 １……基板、２……下部電極膜、３……層間絶縁膜、４
……開口部、５……上部電極膜、６……保護膜。FIG. 1 is a sectional view showing the structure of an embodiment of the present invention. Explanation of symbols 1 ... Substrate, 2 ... Lower electrode film, 3 ... Interlayer insulating film, 4
…… Aperture, 5 …… Upper electrode film, 6 …… Protective film.
Claims (2)
ョセフソン接合は主要回路素子とし、該回路を構成する
薄膜部品相互を電気的に絶縁するための層間絶縁を構成
してなる超電導集積回路において、SrTiO3膜、TiO2膜、
Ti2O5膜、TiC膜、TiN膜およびTiB2膜のうちいずれか一
つを保護膜を含む層間絶縁膜に用いたことを特徴とする
酸化物超電導集積回路。1. A superconducting integrated device comprising a Josephson junction formed by laminating oxide superconductor thin films as a main circuit element, and forming an interlayer insulation for electrically insulating the thin film parts constituting the circuit. In the circuit, SrTiO 3 film, TiO 2 film,
An oxide superconducting integrated circuit characterized by using any one of a Ti 2 O 5 film, a TiC film, a TiN film and a TiB 2 film as an interlayer insulating film including a protective film.
膜のうち、いずれか２つないしそれ以上を含む薄膜を保
護膜を含む層間絶縁膜として用いたことを特徴とする酸
化物超電導集積回路。2. The SrTiO 3 film, the TiO 2 film, the Ti 2 O 5 film, the TiC film, the TiN film and the TiB 2 film according to the first aspect of the invention.
An oxide superconducting integrated circuit, wherein a thin film including any two or more of the films is used as an interlayer insulating film including a protective film.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62165324A JP2544390B2 (en) | 1987-07-03 | 1987-07-03 | Oxide superconducting integrated circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62165324A JP2544390B2 (en) | 1987-07-03 | 1987-07-03 | Oxide superconducting integrated circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6410677A JPS6410677A (en) | 1989-01-13 |
| JP2544390B2 true JP2544390B2 (en) | 1996-10-16 |
Family
ID=15810165
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62165324A Expired - Lifetime JP2544390B2 (en) | 1987-07-03 | 1987-07-03 | Oxide superconducting integrated circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2544390B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5380704A (en) * | 1990-02-02 | 1995-01-10 | Hitachi, Ltd. | Superconducting field effect transistor with increased channel length |
| WO1992020092A1 (en) * | 1991-05-08 | 1992-11-12 | Superconductor Technologies, Inc. | Passivation coating for superconducting thin film device |
-
1987
- 1987-07-03 JP JP62165324A patent/JP2544390B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6410677A (en) | 1989-01-13 |
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