Superconducting thermal detector (bolometer) of terahertz (sub-millimeter wave) radiation

Patent metadata

Field	Value
Publication number	US-2016018267-A1
Application number	US-201414773359-A
Country	US
Kind code	A1
Filing date	Mar 4, 2014
Priority date	Mar 5, 2013
Publication date	Jan 21, 2016
Grant date	—

Abstract

A superconducting thermal detector (bolometer) of THz (sub-millimeter) wave radiation based on sensing the change in the amplitude or phase of a resonator circuit, consisting of a capacitor (Csh) and a superconducting temperature dependent inductor where the said inductor is thermally isolated from the heat bath (chip substrate) by micro-suspensions. The bolometer design includes a thin film inductor located on the membrane, a single or/and multi-layered thin film capacitor, and a thin film absorber of incoming radiation. The bolometer design can also include a lithographic antenna with antenna termination and/or a back reflector beneath the membrane for optimal wavelength detection by the resonance circuit. The superconducting thermal detector (bolometer) and arrays of these detectors operate in a temperature range from 1 Kelvin to 10 Kelvin.

First claim

1 ) A superconducting thermal detector comprising:
a. an absorbing element for absorbing electromagnetic radiation, b. a superconducting inductive element thermally isolated from a substrate and in thermal contact with the absorbing element, and c. a read-out circuit for indicating the absorbed electromagnetic radiation, d. wherein the superconducting inductive element is thermally isolated from the substrate by insulator layer micro-suspensions, e. wherein the superconducting inductive element is electrically connected to a capacitor in order to form a resonator circuit, and f. wherein the read-out circuit is implemented by sensing the change in amplitude and/or phase of the resonator circuit.

2 ) The superconducting thermal detector in accordance with claim 1 , wherein the superconducting inductor phonon system is located on the membrane, whereas the said membrane is thermally isolated from the phonon system of the substrate by micro-suspensions.

3 ) The superconducting thermal detector in accordance with claim 1 , wherein the said superconducting inductive element comprises a superconducting material having a high normal state resistivity.

4 ) The superconducting thermal detector in accordance with claim 1 , wherein the said superconducting inductor comprises a superconducting material such as Aluminium (Al), Niobium (Nb), Vanadium (V), Tungsten silicide (WSi), Magnesium diboride (MgB 2 ) or other-like superconducting material having superconducting transition temperatures in temperature range 1 Kelvin-20 Kelvin.

5 ) The superconducting thermal detector in accordance with claim 1 , wherein the said superconducting inductor comprises a superconducting material comprising nitrogen (N) and a metal selected from the group consisting of Niobium (Nb), Titanium (Ti) and Vanadium (V).

6 ) The superconducting thermal detector in accordance with claim 1 , further comprising utilizing kinetic inductance thermometry which is read out by a scattering parameter measurement which can be used to determine the amplitude or phase change in the resonator induced by impinging optical power.

7 ) The superconducting thermal detector in accordance with claim 1 , wherein it utilizes kinetic inductance thermometry and incorporates an impedance matching surface for efficient absorption of incident optical power.

8 ) The superconducting thermal detector in accordance with claim 1 , wherein it utilizes kinetic inductance thermometry and incorporates an antenna and an antenna termination which dissipates the incident optical power and translates it to heat to be sensed by the kinetic inductance thermometer.

9 ) (canceled)

10 ) A bolometer array comprising linear or 2-dimensional matrix of the superconducting thermal detectors having individual bolometer resonant circuits with different resonant frequencies coupled to a superconducting transmission line by either via a capacitance or via an inductance or via a circuit containing both inductive and capacitive elements, wherein each superconducting thermal detector has: an absorbing element for absorbing electromagnetic radiation, superconducting inductive element thermally isolated from a substrate and in thermal contact with the absorbing element, and a read-out circuit for indicating the absorbed electromagnetic radiation, wherein the superconducting inductive element is thermally isolated from the substrate by insulator layer micro-suspensions, wherein the superconducting inductive element is electrically connected to a capacitor in order to form a resonator circuit, and wherein the read-out circuit is implemented by sensing the changing in amplitude and/or phase of the resonator circuit.

11 ) A method for manufacturing a superconducting thermal detector comprising:
a. deposition of a membrane layer onto a silicon substrate, b. deposition of superconducting inductor layer over the membrane layer by sputtering method in argon atmosphere, c. deposition of insulator layer over the superconducting inductor layer, d. deposition of absorber layer over the insulator layer followed by wet etching or by dry etching to form absorbing element, and, e. forming micro-suspensions in order to isolate thermally the part of the superconducting inductor layer forming superconducting inductive element from the substrate.

12 ) The method in accordance with claim 11 , further comprising deep etching of silicon to release the membrane layer by anisotropic silicon ICP etching or by wet etching.

13 ) The method in accordance with claim 11 , further comprising deposition of etch-stop layer such as silicon oxide or onto a silicon substrate.

14 ) The method in accordance with claim 11 , wherein the membrane layer comprises a 100 nm to 1 μm thick film of a material including a silicon nitride (SiN, Si 3 N 4 ) or a silicon oxide (SiO, SiO 2 ).

15 ) The method in accordance with claim 11 , wherein the superconducting inductor comprises a 3 nm to 500 nm thick film of a superconducting material selected from niobium (Nb), niobium nitride (NbN) or niobium titanium nitride (NbTiN) and that the material of superconducting inductor layer is selected from the following: Nb, NbN, or NbTiN, and other superconducting materials such as aluminium (Al), vanadium (V), vanadium nitride (VN), tungsten silicide (WSi) and magnesium diboride (MgB 2 ).

16 ) The method in accordance with claim 11 , wherein the superconducting inductor layer is patterned by micro-lithography and by wet etching or by plasma etching.

17 ) The method in accordance with claim 11 , wherein the insulator layer material comprises a 10 nm to 1 μm thick film of silicon nitride (SiN, Si 3 N 4 ), a silicon oxide (SiO, SiO 2 ), or aluminium oxide (AlO, Al 2 O 3 ).

18 ) The method in accordance with claim 11 , wherein the insulator layer is patterned by micro-lithography and by wet etching or by plasma etching.

19 ) The method in accordance with claim 11 , further comprising deposition of a 2 nd superconducting layer comprising a 3 nm to 1 μm thick film of superconducting material.

20 ) The method in accordance with claim 11 , wherein the 2 nd superconducting layer is patterned by micro-lithography and by wet etching or by plasma etching

21 ) The method in accordance with claim 11 , wherein the material of an absorbing element comprises a normal metal 100 nm thick film of titanium tungsten (TiW) and the material of absorbing element is selected from TiW, Mo, and Ti.

22 ) The method in accordance with claim 11 , further comprising forming membrane perforations and micro-suspension legs to enhance thermal isolation of a superconducting inductor or/and absorbing element.

23 ) The method in accordance with claim 11 , wherein the perforations in the membrane layer are patterned by micro-lithography and by wet etching or by plasma etching.

24 ) The method in accordance with claim 11 , wherein in order to enhance absorption of THz radiation, an optical cavity of a gap of λ/4 or odd multiples of λ/4:

(

2
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n

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1

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4

,

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Assignees

• Teknologian Tutkimuskeskus Vtt Oy

Inventors

• Timofeev Andrey
• Hassel Juha
• Luukanen Arttu
• Helistö Panu
• Grönberg Leif

Classifications

• G01J2005/208

  superconductive · CPC title

• G01J2005/106

  Arrays · CPC title

• G01J5/20 Primary

  using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices · CPC title

• H01L37/00

  Electricity · mapped topic

• G01J5/024

  Special manufacturing steps or sacrificial layers or layer structures · CPC title