JPS62198175A - Superconducting tunnel junction element - Google Patents
Superconducting tunnel junction elementInfo
- Publication number
- JPS62198175A JPS62198175A JP61039388A JP3938886A JPS62198175A JP S62198175 A JPS62198175 A JP S62198175A JP 61039388 A JP61039388 A JP 61039388A JP 3938886 A JP3938886 A JP 3938886A JP S62198175 A JPS62198175 A JP S62198175A
- Authority
- JP
- Japan
- Prior art keywords
- metal film
- tunnel junction
- electrode
- lower electrode
- superconducting
- 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
- 229910052751 metal Inorganic materials 0.000 claims abstract description 35
- 239000002184 metal Substances 0.000 claims abstract description 35
- 239000007789 gas Substances 0.000 claims abstract description 19
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims abstract description 14
- 230000004888 barrier function Effects 0.000 claims abstract description 9
- 229910052786 argon Inorganic materials 0.000 claims abstract description 7
- 229910052724 xenon Inorganic materials 0.000 claims description 2
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 claims description 2
- 230000001590 oxidative effect Effects 0.000 claims 1
- TXEYQDLBPFQVAA-UHFFFAOYSA-N tetrafluoromethane Chemical compound FC(F)(F)F TXEYQDLBPFQVAA-UHFFFAOYSA-N 0.000 claims 1
- 230000006866 deterioration Effects 0.000 abstract description 7
- 238000004519 manufacturing process Methods 0.000 abstract description 4
- 239000010410 layer Substances 0.000 abstract 2
- 239000011229 interlayer Substances 0.000 abstract 1
- 239000010955 niobium Substances 0.000 description 10
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 5
- 229910052758 niobium Inorganic materials 0.000 description 5
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 5
- 239000010931 gold Substances 0.000 description 4
- 229910052737 gold Inorganic materials 0.000 description 4
- 239000000758 substrate Substances 0.000 description 4
- 229910000978 Pb alloy Inorganic materials 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 3
- 238000007740 vapor deposition Methods 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 238000001312 dry etching Methods 0.000 description 1
- 238000005566 electron beam evaporation Methods 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 210000004709 eyebrow Anatomy 0.000 description 1
- 239000005350 fused silica glass Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000000206 photolithography 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
- H10N60/01—Manufacture or treatment
- H10N60/0912—Manufacture or treatment of Josephson-effect devices
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
この発明は超伝導トンネル接合素子に関し、特に異種金
属の酸化膜をトンネル障壁とする素子において、異種金
）、’ＨＩＩｔ’を薄くしたものに関するものである。[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a superconducting tunnel junction device, and particularly relates to a device in which an oxide film of a different metal is used as a tunnel barrier, and in which a thin layer of ``HIIt'' is used. It is something.
第１図は従来の超伝導トンネル接合素子の一例を示した
ものである。図において、■はシリコン（Ｓｉ）、溶融
石英（Ｓｉ０２）等からなる基板、２はニオブ（Ｎｂ）
等からなる超伝導金属膜（下部電極）、３はアルｔ（Ａ
Ｉ）等からなる異種金属膜、４はシリコン、シリコンモ
ノオキサイド（Ｓｉｎ）等からなる眉間絶縁層、５は異
種金属ＩＩｕ３の酸化膜からなるトンネル障壁、６はニ
オブ等からなる超伝導金属膜（上部電極）、７は鉛合金
（Ｐｂ／Ｉｎ）、ニオブ等からなる超伝導金属膜（配線
層）である。FIG. 1 shows an example of a conventional superconducting tunnel junction element. In the figure, ■ is a substrate made of silicon (Si), fused silica (Si02), etc., and 2 is niobium (Nb).
3 is a superconducting metal film (lower electrode) consisting of Alt (A
4 is a glabellar insulating layer made of silicon, silicon monooxide (Sin), etc., 5 is a tunnel barrier made of an oxide film of a dissimilar metal IIu3, 6 is a superconducting metal film made of niobium, etc. 7 is a superconducting metal film (wiring layer) made of lead alloy (Pb/In), niobium, etc.
以下、従来素子の製作方法を説明する。たとえばＳｉか
らなる基板１上仝而に、たとえばＮｂからなる下部電極
２を電子ビームＭ着法により蒸着形成する０次に、高真
空中で冷却した後、その上にたとえばＡＩからなる異種
金属ｌｌ＊３を蒸着形成する。次に、該異種金ＪＨＩ５
３表面全面をたとえば酸素ガス中で熱酸化してトンネル
障壁５上５を形成」−る。さらに該トンネル障壁５上に
たとえばＮｂからなる上部電極６を電子ビーム蒸着法に
よる蒸着形成する。そして、上記基板１上全面に形成さ
れた上記異種金属膜３．トンネル障壁５．上部電極６を
写真製版技術、ドライエツチング技術により全てエツチ
ングして接合面積を決定し、眉間絶縁のためにたとえば
ＳｉＯからなる眉間絶縁層４を蒸着形成する。その後、
配線層としてたとえば鉛合金（Ｐ ｂ ／ Ｉ ｎ ）
からなる超伝導金Ｕ！２Ｉ７を蒸着形成して接合素子を
得る。Hereinafter, a method of manufacturing the conventional element will be explained. A lower electrode 2 made of Nb, for example, is formed by vapor deposition on a substrate 1 made of Si, for example, by electron beam M deposition.Next, after cooling in a high vacuum, a dissimilar metal made of AI, for example, is deposited thereon. *3 is formed by vapor deposition. Next, the dissimilar gold JHI5
The entire surface of the tunnel barrier 5 is thermally oxidized in, for example, oxygen gas to form the tunnel barrier 5. Furthermore, an upper electrode 6 made of, for example, Nb is formed on the tunnel barrier 5 by electron beam evaporation. Then, the dissimilar metal film 3 is formed on the entire surface of the substrate 1. Tunnel barrier5. The upper electrode 6 is entirely etched by photolithography and dry etching to determine the bonding area, and a glabellar insulating layer 4 made of SiO, for example, is vapor-deposited for glabellar insulation. after that,
For example, lead alloy (P b / I n ) is used as the wiring layer.
Superconducting gold U! 2I7 is deposited to obtain a bonding element.
従来の素子は以上のように構成されているので、異種金
Ｂ膜はピンホールをなくすためその膜厚が約１４０人と
比較的厚いものであった。そのため厚い異種金属膜によ
る近接効果によりギャップ電圧が減少するなど素子特性
が劣化するという問題点があった。Since the conventional element is constructed as described above, the thickness of the dissimilar gold B film is relatively thick, about 140 mm, in order to eliminate pinholes. Therefore, there is a problem in that the device characteristics deteriorate, such as a decrease in gap voltage due to the proximity effect caused by the thick dissimilar metal film.
この発明は上記のような問題点を解消するためになされ
たもので、従来よりも薄い、ピンホールのない異種金属
膜からなり、素子特性の劣化を生じない超伝導トンネル
接合素子を得ることを目的とする。This invention was made in order to solve the above-mentioned problems, and aims to obtain a superconducting tunnel junction device that is made of a pinhole-free dissimilar metal film that is thinner than conventional ones and that does not cause deterioration of device characteristics. purpose.
この発明に係る超伝導トンネル接合素子は、下部電極上
に異種金属膜を蒸着形成する前に、該下部電極表面を高
純度のガス雰囲気中に暴露するようにしたものである。In the superconducting tunnel junction device according to the present invention, the surface of the lower electrode is exposed to a high-purity gas atmosphere before a dissimilar metal film is deposited on the lower electrode.
この発明においては、下部電極上に異種金属膜を形成す
る前に、該下部電極表面を高純度ガス雰囲気中に暴露す
るようにしたので、該ガスが該下部電極表面に吸着し、
従来よりも膜厚の薄いピンホールのない異種金属膜で下
部電極表面を覆うことができ、近接効果による素子動性
の劣化のない素子が得られる。In this invention, before forming a dissimilar metal film on the lower electrode, the surface of the lower electrode is exposed to a high purity gas atmosphere, so that the gas is adsorbed to the surface of the lower electrode,
The surface of the lower electrode can be covered with a pinhole-free dissimilar metal film that is thinner than the conventional film, and an element without deterioration of element dynamics due to proximity effect can be obtained.
以下この発明の一実施例について説明する。 An embodiment of this invention will be described below.
第１図は本発明の一実施例による超伝導トンネル接合素
子を示す。図において、従来素子と同一符号は同じもの
を示し、吸着されたガスは図示していない。FIG. 1 shows a superconducting tunnel junction device according to one embodiment of the invention. In the figure, the same reference numerals as in the conventional element indicate the same elements, and the adsorbed gas is not shown.
本実施例素子の製作方法は、従来と同様に形成された下
部電極２の表面を高純度のアルゴンガス雰囲気中に暴露
した後、異種金属膜３を形成し、その後、従来と同様に
、トンネル障壁５、上部電極６、眉間絶縁層４、配線層
７を形成するものである。このような製作方法によれば
、アルゴンガスが下部電極２表面に吸着し、該下部電極
２上に従来よりも膜厚が薄くてピンホールのない異種金
属膜３を形成することができるので、近接効果による素
子特性の劣化を生じない超伝導トンネル接合素子を得る
ことができる。The method of manufacturing the device of this example is to expose the surface of the lower electrode 2 formed in the same manner as before to a high-purity argon gas atmosphere, then form the dissimilar metal film 3, and then, as in the conventional case, to A barrier 5, an upper electrode 6, a glabella insulating layer 4, and a wiring layer 7 are formed. According to such a manufacturing method, argon gas is adsorbed to the surface of the lower electrode 2, and a dissimilar metal film 3 that is thinner than before and has no pinholes can be formed on the lower electrode 2. A superconducting tunnel junction device that does not cause deterioration of device characteristics due to the proximity effect can be obtained.
第２図（ｂ）は従来の超伝導トンネル接合素子の電流−
電圧特性を示し、該素子は、超伝導金属膜（下部電極）
２はニオブ（Ｎｂ）からなり約１０００人厚、異種金属
膜３はアル−、（ＡＩ）からなり約６０人、酸化条件は
Ｉ Ｔｏｒｒ純酸素中で３０分間室温熱酸化、超伝導金
属膜（上部電極）５はニオブ（Ｎｂ）からなり約１００
０人、眉間絶縁層４はシリコンモノオキサイド（Ｓｉｎ
）からなり約３０００人、超伝導金属膜（配線層）７ば
鉛合金（ｒ’ｂ／Ｉｎ）からなり約５０００人であり、
また下部電極２を蒸着形成したのち異種金属（ＡＩ）を
蒸着するまでの間に１０−９ Ｔｏｒｒオーダの高真空
中で冷却を行なったものである。Figure 2(b) shows the current of the conventional superconducting tunnel junction device.
The device has a superconducting metal film (lower electrode)
2 is made of niobium (Nb) and has a thickness of about 1,000. The dissimilar metal film 3 is made of aluminum and (AI) and has a thickness of about 60. The upper electrode) 5 is made of niobium (Nb) and has a thickness of about 100
0 people, the glabellar insulating layer 4 is made of silicon monooxide (Sin).
) and about 3,000 people, and about 5,000 people made of superconducting metal film (wiring layer) 7 and lead alloy (r'b/In).
Furthermore, cooling was performed in a high vacuum of the order of 10<-9 >Torr between the time the lower electrode 2 was formed by vapor deposition and the time before the different metal (AI) was vapor-deposited.
第２図（ａ）は本発明の一実施例による超伝導トンネル
接合素子の電流−電圧特性を示し、該素子は、下部電極
２を蒸着形成してからその表面を１ｍＴ。FIG. 2(a) shows the current-voltage characteristics of a superconducting tunnel junction device according to an embodiment of the present invention, in which a lower electrode 2 is deposited and then its surface is heated at 1 mT.
ｒｒのアルゴンガス雰囲気中に１０分間暴露した後、異
種金属（ＡＩ）を蒸着したものであり、その膜厚、酸化
条件等は従来素子と同じである。図において、１）は特
性曲線ＩＯの縦軸を１０倍に拡大した波型を示す。After being exposed to an argon gas atmosphere of RR for 10 minutes, a different metal (AI) was vapor-deposited, and the film thickness, oxidation conditions, etc. are the same as those of the conventional element. In the figure, 1) shows a waveform in which the vertical axis of the characteristic curve IO is expanded ten times.
ここで第２図ｆｂｌの電流−電圧特性では、ギャップ電
圧以下の電圧でのリーク電流が大きく、異種金属膜３が
下部電極２表面を均一に覆っ°ζおらず、ピンホールが
多く存在していることがわかる。もちろん、ガスによる
暴露を行なわなくても、異種金属膜３を約１４０人まで
厚くすることにより、ピンホールをなくしてギャップ電
圧以下の電圧でのリーク電流を減少させることができる
が、その場合には、厚い異種金［１）９３による近接効
果のためギャップ電圧の減少などの素子特性の劣化をも
たらすこととなる。第２図（ａｌの電流−電圧特性では
、第２図（ｂｌと異種金属膜３の膜厚が同じであるにも
かかわらず、ギャップ電圧以下の電圧でのリーク電流が
減少しており、下部電極２表面を異種金属膜３がピンホ
ールなく覆っていることがわかる。In the current-voltage characteristics shown in FIG. 2 fbl, the leakage current is large at voltages below the gap voltage, and the dissimilar metal film 3 does not cover the surface of the lower electrode 2 uniformly, and there are many pinholes. I know that there is. Of course, even without gas exposure, it is possible to eliminate pinholes and reduce leakage current at voltages below the gap voltage by increasing the thickness of the dissimilar metal film 3 to about 140 mm. This results in deterioration of device characteristics such as a decrease in gap voltage due to the proximity effect due to the thick dissimilar gold [1] 93. In the current-voltage characteristics of Figure 2 (al), the leakage current at a voltage below the gap voltage decreases, even though the thickness of the dissimilar metal film 3 is the same as that of Figure 2 (bl). It can be seen that the dissimilar metal film 3 covers the surface of the electrode 2 without pinholes.
なお、上記実施例では、高純度ガスとしてアルゴンガス
を用いているが、他のガスたとえばキセノン（Ｘｅ）等
の不活性ガスでも同様の効果が期待でき、また、下部電
極と化学反応してその転位温度（Ｔｃ）を下げるもので
なければ、不活性ガス以外のガスたとえばＣＦ４ガスで
も良い。In the above example, argon gas is used as the high-purity gas, but other gases such as inert gases such as xenon (Xe) can also be expected to have similar effects, and may also chemically react with the lower electrode. Gases other than inert gases, such as CF4 gas, may be used as long as they do not lower the dislocation temperature (Tc).
以上のように、この発明の超伝導トンネル接合素子によ
れば、下部電極上に異種金属膜を蒸着形成する前に、該
下部電極を高純度のガス雰囲気中に暴露するようにした
ので、従来よりも膜厚の薄いピンホールのない異種金属
膜で該下部電極表面を覆うことができ、近接効果による
素子特性の劣化のない素子を得ることができる。As described above, according to the superconducting tunnel junction device of the present invention, the lower electrode is exposed to a high-purity gas atmosphere before the dissimilar metal film is deposited on the lower electrode. The surface of the lower electrode can be covered with a pinhole-free dissimilar metal film that is thinner than the above-mentioned film, and an element without deterioration of element characteristics due to the proximity effect can be obtained.
第１図はこの発明の一実施例及び従来の超伝導トンネル
接合素子を示す断面図、第２図（ａｌはこの発明の一実
施例による超伝導トンネル接合素子の電流−電圧特性、
第２図（ｂ）は従来の超伝導トンネル接合素子の電流−
電圧特性である。
図において、ｌは基板、２は超伝導金属膜（下部電極）
、３は異種金属膜、４は眉間絶縁層、５はトンネル障壁
、６は超伝導金属膜（上部電極）、７は超伝導金属膜（
配線層）である。
なお図中同一符号は同−又は相当部分を示す。FIG. 1 is a sectional view showing an embodiment of the present invention and a conventional superconducting tunnel junction device, and FIG. 2 (al is the current-voltage characteristic of a superconducting tunnel junction device according to an embodiment of the present invention;
Figure 2(b) shows the current of the conventional superconducting tunnel junction device.
It is a voltage characteristic. In the figure, l is the substrate, 2 is the superconducting metal film (lower electrode)
, 3 is a dissimilar metal film, 4 is an insulating layer between the eyebrows, 5 is a tunnel barrier, 6 is a superconducting metal film (upper electrode), 7 is a superconducting metal film (
wiring layer). Note that the same reference numerals in the figures indicate the same or equivalent parts.
Claims (2)
面を酸化してトンネル障壁を形成してなる超伝導トンネ
ル接合素子において、 上記異種金属膜を形成する前に上記下部電極表面を高純
度のガス雰囲気中に暴露したことを特徴とする超伝導ト
ンネル接合素子。(1) In a superconducting tunnel junction element in which a dissimilar metal film is formed on a lower electrode and a tunnel barrier is formed by oxidizing the dissimilar metal surface, the lower electrode surface is A superconducting tunnel junction device characterized by being exposed to a high purity gas atmosphere.
であることを特徴とする特許請求の範囲第１項記載の超
伝導トンネル接合素子。(2) The superconducting tunnel junction device according to claim 1, wherein the gas is argon, xenon, or carbon tetrafluoride.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61039388A JPS62198175A (en) | 1986-02-25 | 1986-02-25 | Superconducting tunnel junction element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61039388A JPS62198175A (en) | 1986-02-25 | 1986-02-25 | Superconducting tunnel junction element |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS62198175A true JPS62198175A (en) | 1987-09-01 |
Family
ID=12551621
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61039388A Pending JPS62198175A (en) | 1986-02-25 | 1986-02-25 | Superconducting tunnel junction element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS62198175A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4010489A1 (en) * | 1990-03-31 | 1991-10-02 | Dornier Luftfahrt | SUPRALOCIAL ELEMENT |
-
1986
- 1986-02-25 JP JP61039388A patent/JPS62198175A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4010489A1 (en) * | 1990-03-31 | 1991-10-02 | Dornier Luftfahrt | SUPRALOCIAL ELEMENT |
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