JP4822715B2 - Superconducting photon detector - Google Patents

Superconducting photon detector Download PDF

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JP4822715B2
JP4822715B2 JP2005028261A JP2005028261A JP4822715B2 JP 4822715 B2 JP4822715 B2 JP 4822715B2 JP 2005028261 A JP2005028261 A JP 2005028261A JP 2005028261 A JP2005028261 A JP 2005028261A JP 4822715 B2 JP4822715 B2 JP 4822715B2
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photon detector
phonon
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徹 田井野
広昭 明連
進 高田
昌代 吉田
博 仲川
克弥 菊地
昌宏 青柳
博司 赤穗
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National Institute of Advanced Industrial Science and Technology AIST
Saitama University NUC
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Description

本発明は、可視光からX線領域までのフォトンの測定が可能な超伝導フォトン検出器に関し、特に、低ノイズ化を実現したものである。   The present invention relates to a superconducting photon detector capable of measuring photons from visible light to the X-ray region, and in particular, achieves low noise.

フォトン検出器は、医学分野でのレントゲン撮影や、未知の天体から飛来する光や宇宙線のエネルギーの検出、あるいは、半導体製造プロセス中の汚染物質の分析などに幅広く応用されている。
従来、フォトンを計測する検出器として、主に半導体検出器が用いられて来たが、超伝導トンネル接合を利用してフォトンを検出する超伝導フォトン検出器は、半導体検出器に比較して、エネルギー分解能(近接するエネルギーを弁別する分解能)が高く、高速での観測が可能であるため、次世代のフォトン検出器として期待を集めている。
Photon detectors are widely applied to radiography in the medical field, detection of light and cosmic ray energy flying from unknown celestial bodies, or analysis of contaminants in the semiconductor manufacturing process.
Conventionally, semiconductor detectors have been mainly used as detectors for measuring photons, but superconducting photon detectors that detect photons using a superconducting tunnel junction are compared to semiconductor detectors. Since it has high energy resolution (resolution to discriminate nearby energy) and can be observed at high speed, it is expected as a next-generation photon detector.

超伝導フォトン検出器は、図7の模式図に示すように、超伝導体31及び33が絶縁体32で隔てられたサンドイッチ構造の超伝導トンネル接合素子を有している。この素子は、超伝導転移温度の1/10程度の温度に冷却され、また、磁場が印加されて、超伝導状態を担うクーパー対によるトンネル電流が流れないようにされている。この素子に光子が入射すると、クーパー対が壊れて準粒子が生成され、準粒子によるトンネル電流が増加する。このトンネル電流の増加を測定することにより、入射した光子の数やエネルギーを知ることができる。
半導体のエネルギーギャップは1eV程度であるが、超伝導フォトン検出器の場合、超伝導エネルギーギャップが数meVと小さいため、光子のエネルギーで励起されるキャリアー数(準粒子数)が多く、半導体フォトン検出器に比べて高精度の検出が可能になる。
The superconducting photon detector includes a superconducting tunnel junction element having a sandwich structure in which superconductors 31 and 33 are separated by an insulator 32, as shown in the schematic diagram of FIG. This element is cooled to a temperature of about 1/10 of the superconducting transition temperature, and a magnetic field is applied to prevent a tunnel current from flowing due to a Cooper pair responsible for the superconducting state. When a photon is incident on this element, the Cooper pair is broken and quasiparticles are generated, and the tunnel current due to the quasiparticles increases. By measuring this increase in tunneling current, the number and energy of incident photons can be known.
The energy gap of a semiconductor is about 1 eV, but in the case of a superconducting photon detector, since the superconducting energy gap is as small as several meV, the number of carriers excited by photon energy (the number of quasiparticles) is large. High-precision detection is possible as compared to the instrument.

下記非特許文献1には、超伝導トンネル接合素子の製造方法が記載されている。この方法では、フォトリソグラフィ技術を用いて、直径が7.5cmのSi基板上に面積が50μm×50μmの接合素子を多数個形成している。
図8は、この製造方法で形成された超伝導トンネル接合素子の1つの断面を示している。この素子は、Si基板14上に、Si基板14をエッチングから保護するMgO膜15を備え、その上に、微細形状にエッチング加工された、Nbから成る下部超伝導電極13、Al/AlOxから成るトンネルバリア12、及び、Nbから成る上部超伝導電極11の積層体を備え、その上にコーティングされた絶縁用のポリイミド膜16と、ポリイミド膜16のビアホールを通じて下部超伝導電極13及び上部超伝導電極11に接続する配線電極17、18とを備えている。
Si基板14の厚さは400mmであり、MgO膜15は50nm、下部超伝導電極13及び上部超伝導電極11はそれぞれ200nm、トンネルバリア12は15nmの各厚さを有している。
Non-Patent Document 1 below describes a method for manufacturing a superconducting tunnel junction element. In this method, a large number of bonding elements having an area of 50 μm × 50 μm are formed on a Si substrate having a diameter of 7.5 cm by using a photolithography technique.
FIG. 8 shows a cross section of one of the superconducting tunnel junction elements formed by this manufacturing method. This element comprises an MgO film 15 for protecting the Si substrate 14 from etching on the Si substrate 14, and further comprises a lower superconducting electrode 13 made of Nb and Al / AlOx etched into a fine shape. A tunnel barrier 12 and a laminate of an upper superconducting electrode 11 made of Nb are provided, an insulating polyimide film 16 coated thereon, and a lower superconducting electrode 13 and an upper superconducting electrode through via holes in the polyimide film 16. 11 are connected to the wiring electrodes 17 and 18 connected to the wiring 11.
The thickness of the Si substrate 14 is 400 mm, the MgO film 15 has a thickness of 50 nm, the lower superconducting electrode 13 and the upper superconducting electrode 11 have a thickness of 200 nm, and the tunnel barrier 12 has a thickness of 15 nm.

ポリイミド膜16は、ポリイミドの状態で溶媒可溶性を有するポリイミド材料にジアゾナフトキノン系の感光材を添加した感光性溶媒可溶ポリイミドを塗布し、溶媒を飛ばすための加熱処理を施して形成している。このポリイミド膜16は、配線電極層を下層から絶縁する絶縁層として設けられており、ポリイミド膜の厚さは、200nm〜600nmである。この膜にフォトリソグラフィ技術でビアホールを形成し、その上の全面に配線電極層を600nmの厚さに堆積し、不要部分をエッチングで除いて、所定パターンの配線電極17、18を形成している。
素子の加工を終えたSi基板を5mm四方のチップに切断し、このチップを用いて超伝導フォトン検出器が作成される。このように超伝導トンネル接合素子をアレイ化することで検出器の有感面積を稼ぐことができる。
また、従来の超伝導トンネル接合素子では、配線電極の絶縁層をSiO2で形成したものや、Si基板14上のエッチング保護膜をAl23で形成したもの、また、基板にAl23(sapphire)を使用したものなども知られている。
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY,VOL.13,NO.2,JUNE 2003,pp.119〜122
The polyimide film 16 is formed by applying a photosensitive solvent-soluble polyimide obtained by adding a diazonaphthoquinone-based photosensitive material to a polyimide material having solvent solubility in a polyimide state, and performing a heat treatment for removing the solvent. The polyimide film 16 is provided as an insulating layer that insulates the wiring electrode layer from the lower layer, and the thickness of the polyimide film is 200 nm to 600 nm. Via holes are formed in this film by photolithography, wiring electrode layers are deposited on the entire surface thereof to a thickness of 600 nm, unnecessary portions are removed by etching, and wiring electrodes 17 and 18 having a predetermined pattern are formed. .
The processed Si substrate is cut into a 5 mm square chip, and a superconducting photon detector is produced using this chip. Thus, the sensitive area of a detector can be earned by arraying superconducting tunnel junction elements.
In the conventional superconducting tunnel junction element, the insulating layer of the wiring electrode is formed of SiO 2 , the etching protective film on the Si substrate 14 is formed of Al 2 O 3 , and the substrate is formed of Al 2 O. Those using 3 (sapphire) are also known.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL.13, NO.2, JUNE 2003, pp.119-122

しかし、従来の超伝導フォトン検出器では、低エネルギーのノイズが検出される。図9は、従来の超伝導フォトン検出器を用いて5.9KeVのエネルギーを有するX線を観測した結果を示している。この図の横軸は光子のエネルギーを示し、縦軸は光子の計測数を示している。図9が示すように、X線のエネルギーに相当する5.9KeVの箇所で計測数のピークが現れているが、それと共に、0.5eV以下の低エネルギーの高ノイズが検出されている。
このノイズの発生は、図10に示すように、超伝導トンネル接合以外の部分に入射したフォトンが、膜厚の薄い絶縁層16及びエッチング保護膜15を透過して基板14にまで達し、このフォトンのエネルギーを吸収した基板14が振動してフォノンを発生することが原因している。
However, conventional superconducting photon detectors detect low energy noise. FIG. 9 shows the result of observing X-rays having energy of 5.9 KeV using a conventional superconducting photon detector. In this figure, the horizontal axis indicates photon energy, and the vertical axis indicates the number of photons measured. As shown in FIG. 9, a peak of the number of measurements appears at a location of 5.9 KeV corresponding to the energy of X-rays, and at the same time, high noise with low energy of 0.5 eV or less is detected.
As shown in FIG. 10, the generation of this noise is caused by photons incident on portions other than the superconducting tunnel junction passing through the thin insulating layer 16 and the etching protection film 15 and reaching the substrate 14. This is because the substrate 14 that has absorbed the energy generates vibrations to generate phonons.

このフォノンが、基板14を伝わり、エッチング保護膜15を介して超伝導トンネル接合の下部超伝導電極13に達すると、クーパー対が崩壊し、準粒子が発生してトンネル接合のトンネル電流が増加する。フォノンのエネルギーは低く、また、基板14内で多量の数のフォノンが発生するため、フォノンイベントによるノイズは、図9に示すように、低エネルギーの領域において極めて高い値を示す。
そのため、可視光を観測するときのように、識別しようとする光のエネルギーが小さい場合には、そのエネルギースペクトルがフォノンイベントによるスペクトルの中に埋もれて、検出することができなくなる。
When this phonon travels through the substrate 14 and reaches the lower superconducting electrode 13 of the superconducting tunnel junction via the etching protection film 15, the Cooper pair collapses, quasiparticles are generated, and the tunneling current of the tunnel junction increases. . Since the phonon energy is low and a large number of phonons are generated in the substrate 14, the noise due to the phonon event shows a very high value in a low energy region as shown in FIG.
Therefore, when the energy of light to be identified is small as in the case of observing visible light, the energy spectrum is buried in the spectrum due to the phonon event and cannot be detected.

本発明は、こうした従来の問題点を解決するものであり、フォノンイベントによる低エネルギーのノイズを除去することができる超伝導フォトン検出器を提供することを目的としている。   The present invention is intended to solve such a conventional problem, and an object of the present invention is to provide a superconducting photon detector capable of removing low energy noise due to a phonon event.

本発明の超伝導フォトン検出器は、基板と下部超伝導電極との間に介在し、基板から入射する音響波の反射係数の絶対値が透過係数の絶対値よりも大きい材料で形成されたフォノン遮蔽層を備えている。
このフォノン遮蔽層は、基板から下部超伝導電極に入力するフォノンを遮断する。
Superconducting photon detector of the present invention is interposed between the substrate and a lower superconducting electrode, the absolute value of the reflection coefficients of the acoustic wave incident from the substrate is formed with larger material than the absolute value of the transmission coefficient phonons A shielding layer is provided.
The phonon shielding layer blocks phonons input from the substrate to the lower superconducting electrode.

また、本発明の超伝導フォトン検出器は、上部超伝導電極の上に積層された絶縁層と、この絶縁層の上に形成され、絶縁層の孔を通じて下部超伝導電極または上部超伝導電極に接続する配線電極とを備え、この絶縁層の一部が除去されて、上部超伝導電極または下部超伝導電極の少なくとも一部が露出している。
この超伝導フォトン検出器では、低エネルギーの光子が、絶縁層でエネルギーを吸収されることなく、露出箇所から超伝導トンネル接合に入射し、フォノンイベントによるノイズに埋もれること無く計測される。
The superconducting photon detector according to the present invention includes an insulating layer stacked on the upper superconducting electrode, and is formed on the insulating layer, and is formed on the lower superconducting electrode or the upper superconducting electrode through a hole in the insulating layer. And a wiring electrode to be connected. A part of the insulating layer is removed, and at least a part of the upper superconducting electrode or the lower superconducting electrode is exposed.
In this superconducting photon detector, low energy photons are incident on the superconducting tunnel junction from the exposed location without being absorbed by the insulating layer, and are measured without being buried in noise due to phonon events.

また、本発明の超伝導フォトン検出器では、フォノン遮蔽層をポリイミドの膜で形成している。
Si等の基板にポリイミド膜を接合した場合、基板から入射する音響波の接合面での反射係数は極めて大きく、透過係数は極めて小さい。そのため、基板から超伝導トンネル接合へのフォノンの入射を完全に遮蔽することができる。
In the superconducting photon detector of the present invention, the phonon shielding layer is formed of a polyimide film.
When a polyimide film is bonded to a substrate such as Si, the reflection coefficient of the acoustic wave incident from the substrate on the bonding surface is extremely large and the transmission coefficient is extremely small. Therefore, the phonon incidence from the substrate to the superconducting tunnel junction can be completely shielded.

本発明の超伝導フォトン検出器は、フォノンイベントによる低エネルギーのノイズを除去することができ、低エネルギーの可視光を正確に観測することができる。   The superconducting photon detector of the present invention can remove low-energy noise due to phonon events, and can accurately observe low-energy visible light.

図1は、本発明の実施形態における超伝導フォトン検出器の超伝導トンネル接合素子を示している。
この素子は、Si基板14上に、Si基板14で発生したフォノンが超伝導トンネル接合に伝達するのを遮蔽するポリイミド膜20を備えている。その他の構成は、従来の素子(図8)と同じであり、ポリイミド膜20の上にエッチング保護膜15を有し、エッチング保護膜15の上に、Nbから成る下部超伝導電極13、Al/AlOxから成るトンネルバリア12、Nbから成る上部超伝導電極11、絶縁層16、及び、配線電極17、18を備えている。
FIG. 1 shows a superconducting tunnel junction element of a superconducting photon detector according to an embodiment of the present invention.
This element includes a polyimide film 20 on the Si substrate 14 that shields transmission of phonons generated in the Si substrate 14 to the superconducting tunnel junction. The other structure is the same as that of the conventional element (FIG. 8), and has an etching protective film 15 on the polyimide film 20, and the lower superconducting electrode 13 made of Nb, Al / A tunnel barrier 12 made of AlOx, an upper superconducting electrode 11 made of Nb, an insulating layer 16, and wiring electrodes 17 and 18 are provided.

このフォノン遮蔽用ポリイミド膜20は、前記非特許文献1に記載された溶媒可溶性のポリイミド材料を用いて、スピンコーティング法により成形している。
このポリイミド材料は、株式会社ピーアイ技術研究所から市販されている。このポリイミド材料を溶媒に溶かしてSi基板上に滴下し、この基板を、回転数を制御しながら回転することにより、所望の膜厚の均一な膜を形成することができる。
図2は、滴下した液に含まれるポリイミド材料の含有量を変えてスピンコーティングを実施したときの基板の回転数と膜厚との関係を示している。この方法により、膜厚が40nm以上の均質な膜を得ることができる。
This phonon shielding polyimide film 20 is formed by a spin coating method using a solvent-soluble polyimide material described in Non-Patent Document 1.
This polyimide material is commercially available from PI Technical Research Institute. By dissolving this polyimide material in a solvent and dropping it on a Si substrate, and rotating the substrate while controlling the number of rotations, a uniform film having a desired film thickness can be formed.
FIG. 2 shows the relationship between the number of rotations of the substrate and the film thickness when spin coating is performed by changing the content of the polyimide material contained in the dropped liquid. By this method, a homogeneous film having a film thickness of 40 nm or more can be obtained.

スピンコーティング法で成形した膜を150℃程度の温度で10分間加熱乾燥すると、溶媒が除去されてポリイミド膜が生成する。この処理の間に、ポリイミド材料から「ブロック」と呼ばれる単機能のポリイミドが直接合成され、さらに、ブロックが重合してポリイミドが生成される。
このフォノン遮蔽用ポリイミド膜20を形成したSi基板14の上に、エッチング保護膜15、下部超伝導電極13、トンネルバリア12、上部超伝導電極11、絶縁層16及び配線電極17、18を形成する処理は、従来の素子と同じように行うことができる。
When the film formed by the spin coating method is heated and dried at a temperature of about 150 ° C. for 10 minutes, the solvent is removed and a polyimide film is formed. During this process, a single-function polyimide called “block” is directly synthesized from the polyimide material, and the block is polymerized to produce polyimide.
An etching protective film 15, a lower superconducting electrode 13, a tunnel barrier 12, an upper superconducting electrode 11, an insulating layer 16, and wiring electrodes 17 and 18 are formed on the Si substrate 14 on which the phonon shielding polyimide film 20 is formed. The processing can be performed in the same way as a conventional element.

図3は、300nmの膜厚のフォノン遮蔽用ポリイミド膜20を設けた超伝導トンネル接合素子を備える超伝導フォトン検出器により5.9KeVのエネルギーを有するX線を観測した結果を示している。図3から明らかなように、この検出器は、フォノンイベントの影響を完全に遮蔽しており、フォノンに対し無雑音の結果が得られている。
こうした現象は、図4に示すように、基板14から遮蔽層20に入射する音響波の反射波Rと透過波Tとを考慮した場合、ポリイミドの遮蔽層20では、反射の割合が高く、透過の割合が低いために現れる。
FIG. 3 shows the result of observing X-rays having energy of 5.9 KeV with a superconducting photon detector including a superconducting tunnel junction element provided with a phonon shielding polyimide film 20 having a thickness of 300 nm. As is apparent from FIG. 3, this detector completely shields the influence of the phonon event, and a noiseless result is obtained for the phonon.
As shown in FIG. 4, when the reflected wave R and the transmitted wave T of the acoustic wave incident on the shielding layer 20 from the substrate 14 are taken into consideration, such a phenomenon is high in the polyimide shielding layer 20, and the transmission rate is high. Appears because of the low percentage.

図5(a)には、超伝導トンネル接合素子の基板材料として使われているSi及びAl23(sapphire)、従来の超伝導トンネル接合素子でエッチング保護層として使われているMgO及びAl23(layer)、並びに、この実施形態でフォトン遮蔽層を形成するポリイミドの各体積密度(ρ)、弾性係数(C)、及び固有音響インピーダンス(Z)を示し、図5(b)には、基板がSiまたはAl23(sapphire)であって、この基板にMgO、Al23またはポリイミドを接合した場合の透過係数(T)及び反射係数(R)を示している。 FIG. 5A shows Si and Al 2 O 3 (sapphire) used as substrate materials for a superconducting tunnel junction element, and MgO and Al used as an etching protective layer in a conventional superconducting tunnel junction element. 2 O 3 (layer) and the volume density (ρ), elastic modulus (C), and specific acoustic impedance (Z) of polyimide forming the photon shielding layer in this embodiment are shown in FIG. Shows the transmission coefficient (T) and reflection coefficient (R) when the substrate is Si or Al 2 O 3 (sapphire) and MgO, Al 2 O 3 or polyimide is bonded to the substrate.

ここで、Z=√(ρ・C)である。また、T=1+Rが成り立つ。Rは、基板14の固有音響インピーダンスをZsub、遮蔽層20の固有音響インピーダンスをZbufとするとき、
R=(Zsub−Zbuf)/(Zsub+Zbuf
となり、Tは、
T=2Zbuf/(Zsub+Zbuf
となる。
また、反射係数R及び透過係数Tの大きさを見るため、
a=|R|2
a=1−|R|2=1−Ra
を算出している。
Here, Z = √ (ρ · C). Further, T = 1 + R is established. R is Z sub as the specific acoustic impedance of the substrate 14, and Z buf as the specific acoustic impedance of the shielding layer 20.
R = (Z sub −Z buf ) / (Z sub + Z buf )
And T is
T = 2Z buf / (Z sub + Z buf )
It becomes.
In order to see the size of the reflection coefficient R and the transmission coefficient T,
R a = | R | 2
T a = 1− | R | 2 = 1−R a
Is calculated.

図5(b)から明らかなように、MgOやAl23では、基板がSi及びAl23(sapphire)のいずれであっても、反射係数Rの絶対値に比べて透過係数Tの絶対値の方が大きいが、ポリイミドでは、逆に、基板がSi及びAl23(sapphire)のいずれであっても、透過係数Tの絶対値に比べて反射係数Rの絶対値の方が大きい。しかも、透過係数Tの絶対値は、MgOやAl23に比べて、桁違いに小さい。そのため、遮蔽層20を介して下部超伝導電極13に入力するフォノンを完全にシャットアウトすることができる。 As apparent from FIG. 5B, in MgO and Al 2 O 3 , the transmission coefficient T is higher than the absolute value of the reflection coefficient R regardless of whether the substrate is Si or Al 2 O 3 (sapphire). In absolute terms, the absolute value of the reflection coefficient R is greater than the absolute value of the transmission coefficient T, regardless of whether the substrate is Si or Al 2 O 3 (sapphire). large. Moreover, the absolute value of the transmission coefficient T is orders of magnitude smaller than that of MgO or Al 2 O 3 . Therefore, the phonons input to the lower superconducting electrode 13 through the shielding layer 20 can be completely shut out.

図6は、エネルギーが低い可視光の観測に適した超伝導フォトン検出器の超伝導トンネル接合素子を示している。この素子は、Si基板14上にフォノン遮蔽用ポリイミド膜20を設けるとともに、上部超伝導電極11及び下部超伝導電極13を覆う絶縁層16を除去して、上部超伝導電極11及び下部超伝導電極13の一部が露出するように構成している。
この超伝導フォトン検出器では、ポリイミド膜20のためにフォノンによる低エネルギーのノイズが遮蔽され、一方、低エネルギーの可視光は、絶縁層16でエネルギーが吸収されること無く、超伝導トンネル接合素子に入射する。そのため、低エネルギーの可視光を、ノイズに埋もれずに計測することができる。
FIG. 6 shows a superconducting tunnel junction element of a superconducting photon detector suitable for observing visible light with low energy. In this device, a phonon shielding polyimide film 20 is provided on a Si substrate 14 and the insulating layer 16 covering the upper superconducting electrode 11 and the lower superconducting electrode 13 is removed, so that the upper superconducting electrode 11 and the lower superconducting electrode are removed. A part of 13 is exposed.
In this superconducting photon detector, low energy noise due to phonons is shielded by the polyimide film 20, while low energy visible light is not absorbed by the insulating layer 16, and the superconducting tunnel junction device. Is incident on. Therefore, low energy visible light can be measured without being buried in noise.

なお、フォノン遮蔽に用いるポリイミド膜20の膜厚は、均一な厚さが得られる範囲であれば良い。ポリイミド膜20の膜厚が不均一であると、その後に積層する、極めて薄い超伝導トンネル接合のトンネルバリア12に破断などの損傷が生じ、良好な特性が得られない。
また、ポリイミド材料としては、特開2003−98667号公報に記載されている材料などを使用することもできる。
In addition, the film thickness of the polyimide film 20 used for phonon shielding should just be the range in which uniform thickness is obtained. If the film thickness of the polyimide film 20 is not uniform, the tunnel barrier 12 of an extremely thin superconducting tunnel junction to be laminated thereafter is damaged such as breakage, and good characteristics cannot be obtained.
Moreover, as a polyimide material, the material etc. which are described in Unexamined-Japanese-Patent No. 2003-98667 can also be used.

また、ここではフォノン遮蔽層の材料としてポリイミドを用いる場合について説明したが、基板との接合面において、基板から入射する音響波の反射係数の絶対値が透過係数の絶対値より大きくなる材料であって、均一な膜厚が得られる有機材料または無機材料であれば、ポリイミドに代えて用いることができる。
また、ここでは、超伝導トンネル接合素子をエッチングで形成しているため、ポリイミド膜20の上にエッチング保護膜15を設けているが、他の方法で素子を形成する場合には、エッチング保護膜は不要である。
Further, here, the case where polyimide is used as the material of the phonon shielding layer has been described. However, the absolute value of the reflection coefficient of the acoustic wave incident from the substrate is larger than the absolute value of the transmission coefficient at the bonding surface with the substrate. Any organic material or inorganic material that can provide a uniform film thickness can be used instead of polyimide.
Here, since the superconducting tunnel junction element is formed by etching, the etching protection film 15 is provided on the polyimide film 20. However, when the element is formed by other methods, the etching protection film is provided. Is unnecessary.

本発明の超伝導フォトン検出器は、レントゲン撮影を行う医学分野、星の光や宇宙線を観測する天文分野、半導体製造プロセス中の汚染物質を分析する工業分野など、各種分野において、低エネルギーのフォトンが観測できる検出器として幅広く利用することができる。   The superconducting photon detector of the present invention has low energy in various fields such as the medical field for X-ray imaging, the astronomical field for observing star light and cosmic rays, and the industrial field for analyzing contaminants in the semiconductor manufacturing process. It can be widely used as a detector that can observe photons.

本発明の実施形態における超伝導フォトン検出器の超伝導トンネル接合素子を示す図The figure which shows the superconducting tunnel junction element of the superconducting photon detector in embodiment of this invention スピンコーティング法でフォノン遮蔽層を形成する場合の回転数と膜厚との関係を示す図Diagram showing the relationship between the number of rotations and film thickness when forming a phonon shielding layer by spin coating 本発明の実施形態における超伝導フォトン検出器での検出結果を示す図The figure which shows the detection result in the superconducting photon detector in embodiment of this invention 基板及びフォノン遮蔽層の接合面での入射波、反射波及び透過波を説明する図The figure explaining the incident wave in the joint surface of a board | substrate and a phonon shielding layer, a reflected wave, and a transmitted wave 本発明の実施形態においてフォノン遮蔽層に用いたポリイミド、及び比較材料のパラメータを示す図The figure which shows the parameter of the polyimide used for the phonon shielding layer in embodiment of this invention, and a comparison material 本発明の実施形態における、低エネルギーのフォトン観測に適した超伝導フォトン検出器の超伝導トンネル接合素子を示す図The figure which shows the superconducting tunnel junction element of the superconducting photon detector suitable for low energy photon observation in embodiment of this invention 超伝導フォトン検出器の原理を説明する図Diagram explaining the principle of superconducting photon detector 従来の超伝導トンネル接合素子の構造を示す図Diagram showing the structure of a conventional superconducting tunnel junction device 従来の超伝導フォトン検出器での検出結果を示す図The figure which shows the detection result with the conventional superconducting photon detector 従来の超伝導フォトン検出器におけるノイズ発生原因を説明する図Diagram explaining the cause of noise generation in a conventional superconducting photon detector

符号の説明Explanation of symbols

11 上部超伝導電極
12 トンネルバリア
13 下部超伝導電極
14 Si基板
15 MgO膜
16 絶縁膜
17 配線電極
18 配線電極
20 フォノン遮蔽層
31 超伝導体
32 絶縁体
33 超伝導体
DESCRIPTION OF SYMBOLS 11 Upper superconducting electrode 12 Tunnel barrier 13 Lower superconducting electrode 14 Si substrate 15 MgO film 16 Insulating film 17 Wiring electrode 18 Wiring electrode 20 Phonon shielding layer 31 Superconductor 32 Insulator 33 Superconductor

Claims (3)

基板上に積層された下部超伝導電極、トンネルバリア及び上部超伝導電極を有する超伝導フォトン検出器であって、
前記基板と前記下部超伝導電極との間に介在し、前記基板から入射する音響波の反射係数の絶対値が透過係数の絶対値よりも大きい材料で形成されたフォノン遮蔽層を備える超伝導フォトン検出器。
A superconducting photon detector having a lower superconducting electrode, a tunnel barrier and an upper superconducting electrode stacked on a substrate,
Interposed between the lower superconducting electrode and the substrate, the superconducting photons having the absolute value phonon shielding layer formed of a larger material than the absolute value transmission coefficient of the reflection coefficient of the acoustic wave incident from the substrate Detector.
請求項1に記載の超伝導フォトン検出器であって、前記上部超伝導電極の上に積層された絶縁層と、前記絶縁層の上に形成され、前記絶縁層の孔を通じて前記下部超伝導電極または上部超伝導電極に接続する配線電極とを備え、前記絶縁層の一部が除去されて、前記上部超伝導電極または下部超伝導電極の少なくとも一部が露出している超伝導フォトン検出器。   2. The superconducting photon detector according to claim 1, wherein an insulating layer is formed on the upper superconducting electrode, and the lower superconducting electrode is formed on the insulating layer and through a hole of the insulating layer. Alternatively, a superconducting photon detector comprising a wiring electrode connected to the upper superconducting electrode, wherein a part of the insulating layer is removed and at least a part of the upper superconducting electrode or the lower superconducting electrode is exposed. 請求項1または2に記載の超伝導フォトン検出器であって、前記フォノン遮蔽層がポリイミドの膜から成る超伝導フォトン検出器。   3. The superconducting photon detector according to claim 1, wherein the phonon shielding layer is made of a polyimide film.
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