Superconducting dynamic inductance detector with high sensitivity and high stability and preparation method thereof

Abstract

The invention discloses a superconductive dynamic inductance detector with high sensitivity and high stability and a preparation method, the superconductive dynamic inductance detector comprises a silicon substrate, and a coplanar waveguide transmission line and a superconductive microwave resonator with a mixed structure which are manufactured on the upper surface of the silicon substrate, and the superconductive microwave resonator with the mixed structure is composed of a double-helix inductor and an interdigital capacitor which are connected in parallel; the double-helix inductor is made of a beta-Ta film, and the interdigital capacitor is made of an alpha-Ta film. According to the mixed structure provided by the invention, the characteristics of low loss of alpha-Ta and relatively large dynamic inductance coefficient of beta-Ta are utilized, the sensitivity of the dynamic inductance detector is greatly improved, and meanwhile, Ta has good temperature stability and still has good detection performance after multiple thermal and cold cycles; the sensitivity of the detector is generally described by noise equivalent power, the smaller the noise equivalent power is, the higher the sensitivity is, the noise equivalent power of the detector is as low as 8 * 10 <-19 > W / Hz1 / 2, and the detector still has extremely high sensitivity after multiple temperature cycles.

Description

Technical Field

[0001] The present invention relates to the field of terahertz detection technology, and in particular to a high-sensitivity and high-stability superconducting dynamic inductance detector and a preparation method thereof. Background Art

[0002] Terahertz waves refer to electromagnetic waves with a frequency between 0.1THz and 10THz, which is between microwave and infrared bands. Currently, common superconducting terahertz direct detectors mainly include superconducting transition edge sensors, superconducting quantum capacitance detectors, and superconducting dynamic inductance detectors. Superconducting dynamic inductance detectors have broad application prospects in terahertz detection, astronomical detection, quantum sensing and other fields due to their extremely high sensitivity, frequency division multiplexing readout method, and easy array expansion.

[0003] The superconducting dynamic inductance detector mainly consists of two parts: a microwave transmission line and a superconducting microwave resonator. The microwave resonator consists of an interdigital capacitor and an inductor in parallel, and the inductor part usually has the ability to couple photon signals. Limited by the material properties and detector structure, the existing dynamic inductance detector has poor stability and the detection sensitivity decreases after multiple temperature cycles. Summary of the invention

[0004] Purpose of the invention: The present invention provides a highly sensitive and highly stable superconducting dynamic inductance detector and a preparation method thereof, which has high stability while ensuring extremely high sensitivity.

[0005] Technical solution: The high-sensitivity and high-stability superconducting dynamic inductance detector described in the present invention includes: a silicon substrate and a coplanar waveguide transmission line and a hybrid structure superconducting microwave resonator made on the upper surface of the silicon substrate. The hybrid structure superconducting microwave resonator consists of a double helix inductor and a cross-finger capacitor connected in parallel. The double helix inductor is made of β-Ta film, and the cross-finger capacitor is made of α-Ta film.

[0006] Furthermore, the width of the double spiral inductor is 1-5 μm, and the interval is the same as the width.

[0007] Furthermore, the width of the interdigital capacitor is 1-5 μm, and the interdigital spacing is the same as the width.

[0008] Furthermore, the number of turns of the double-helix inductor is 10-20, and the number of interdigital indexes of the interdigital capacitor is 20-80 pairs.

[0009] Furthermore, the thickness of the double spiral inductor is 20-60 μm, and the thickness of the interdigital capacitor is 100-200 μm.

[0010] Accordingly, a method for preparing a superconducting dynamic inductance detector with high sensitivity and high stability comprises the following steps:

[0011] Step 1: Prepare a clean silicon substrate;

[0012] Step 2, growing a layer of α-Ta film using a magnetron sputtering apparatus;

[0013] Step 3, spin-coat a layer of AZ1500 photoresist;

[0014] Step 4, using a photolithography machine to transfer the pattern of the coplanar waveguide transmission line and the interdigital capacitor to the photoresist;

[0015] Step 5, using zjx-100 developer to develop and fix the pattern transferred to the photoresist;

[0016] Step 6: etching the pattern using reactive ion beam etching technology to transfer the pattern on the photoresist to the α-Ta film grown in step 2;

[0017] Step 7, cleaning the photoresist on the substrate obtained in step 6;

[0018] Step 8, first spin-coat LOR-10B photoresist on the substrate cleaned in step 7, and then spin-coat AZ1500 photoresist;

[0019] Step 9: Use a photolithography machine to expose the double-helix inductor area into a square blank area, the area size is 5-10μm larger than the inductor outline;

[0020] Step 10, using zjx-100 developer to develop and fix the pattern on the photoresist;

[0021] Step 11, growing a layer of β-Ta film on the substrate obtained in step 10 using a magnetron sputtering apparatus;

[0022] Step 12, placing the substrate obtained in step 11 in N-methylpyrrolidone and heating it in a water bath for 5-20 hours, cleaning the photoresist spin-coated in step 8 and obtaining a β-Ta film in the double helix inductor region;

[0023] Step 13, spin coating a layer of AZ1500 photoresist on the substrate obtained in step 12;

[0024] Step 14, using a photolithography machine to transfer the pattern of the double spiral inductor onto the photoresist obtained in step 13;

[0025] Step 15, using zjx-100 developer to develop and fix the pattern on the photoresist;

[0026] Step 16, etching the pattern using reactive ion beam etching technology to transfer the pattern on the photoresist to the β-Ta film grown in step 11;

[0027] Step 17: Clean the photoresist on the substrate obtained in step 16 to obtain a terahertz superconducting dynamic inductance detector with a hybrid structure.

[0028] Furthermore, in step 1, high-resistance silicon is selected for the silicon substrate, and a buffered oxide etching solution is used to remove the surface oxide layer.

[0029] Furthermore, in step 2, α-Ta is grown at 500°C.

[0030] Furthermore, in step 3 and step 8, the AZ1500 photoresist should be baked at 95° C. for 3 minutes.

[0031] Furthermore, in step 6 and step 16, the reactive ion beam etching uses carbon tetrafluoride as the etching gas.

[0032] Furthermore, in step 8, the LOR-10B photoresist should be baked at 150° C. for 5 minutes.

[0033] Furthermore, in step 11, β-Ta is grown at room temperature.

[0034] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: the present invention proposes a mixed structure of α-Ta and β-Ta, which takes advantage of the low loss of α-Ta and the large dynamic inductance coefficient of β-Ta, greatly improving the sensitivity of the dynamic inductance detector. At the same time, Ta has good temperature stability and still has good detection performance after multiple hot and cold cycles. The sensitivity of the detector is generally described by the noise equivalent power (NEP). The smaller the noise equivalent power, the higher the sensitivity. The noise equivalent power of the detector is as low as 8×10 -19 W / Hz 1 / 2 After many hot and cold cycles, the detector still has extremely high sensitivity. After many hot and cold cycles, the quality factor Q and noise equivalent power NEP of the detector remain stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the detector structure of the present invention.

[0036] Figure 2 Schematic diagram of detector noise equivalent power of the present invention.

[0037] Figure 3 It is a schematic diagram of the quality factor and noise equivalent power in each hot and cold cycle of the detector of the present invention.

[0038] Among them, 1. reference ground; 2. coplanar waveguide transmission line; 3. β-Ta double helix inductor; 4. α-Ta interdigital capacitor. DETAILED DESCRIPTION

[0039] like Figure 1 As shown, a highly sensitive and highly stable superconducting dynamic inductance detector comprises: a silicon substrate, a coplanar waveguide transmission line and a hybrid structure superconducting microwave resonator made on the upper surface of the silicon substrate, wherein the hybrid structure superconducting microwave resonator is composed of a double helix inductor and a forked capacitor connected in parallel, wherein the double helix inductor is made of β-Ta film, and the forked capacitor is made of α-Ta film. The central conductor width of the coplanar waveguide transmission line is 10 μm, and the distance between the central conductor and the reference ground is 6 μm. The line width of the double helix inductor is 2 μm, and the line width of the forked capacitor is 2 μm. The distance between the resonator and the reference ground is 10 μm.

[0040] Accordingly, a method for preparing a superconducting dynamic inductance detector with high sensitivity and high stability comprises the following steps:

[0041] Step 1: Prepare a clean silicon substrate;

[0042] Step 2: growing a layer of α-Ta film with a thickness of 200 nm by using a magnetron sputtering apparatus;

[0043] Step 3, spin coating a layer of AZ1500 photoresist at a speed of 4000 rpm for 40 seconds;

[0044] Step 4: Use a photolithography machine to transfer the pattern of the coplanar waveguide transmission line and the interdigital capacitor to the photoresist, with an exposure dose of 120mJ / cm 2 ;

[0045] Step 5, using zjx-100 developer to develop and fix the pattern transferred to the photoresist, the developing time is 15 seconds;

[0046] Step 6: Use reactive ion beam etching technology to etch the pattern and transfer the pattern on the photoresist to the α-Ta film grown in the second step. The etching gas is CF 4 , the etching time is 4 minutes;

[0047] Step 7, cleaning the photoresist on the substrate obtained in step 6;

[0048] Step 8, first spin-coating LOR-10B photoresist on the substrate cleaned in step 7, the spin-coating speed is 4000 rpm, and the time is 40 seconds; then spin-coating AZ1500 photoresist, the spin-coating speed is 4000 rpm, and the time is 40 seconds;

[0049] Step 9: Use a photolithography machine to expose the double-helix inductor area into a square blank area. The area size is 5-10μm larger than the inductor outline. The exposure dose is 150mJ / cm 2 ;

[0050] Step 10, using zjx-100 developer to develop and fix the pattern on the photoresist, the response time is 15 seconds;

[0051] Step 11, growing a layer of β-Ta with a thickness of 30 nm on the substrate obtained in step 10 by using a magnetron sputtering apparatus;

[0052] Step 12, placing the substrate obtained in step 11 in N-methylpyrrolidone and heating it in a water bath at 80° C. for 12 hours, cleaning the photoresist spin-coated in step 8 and obtaining a β-Ta film in the double helix inductor region;

[0053] Step 13, spin coating a layer of AZ1500 photoresist on the substrate obtained in step 12, the spin coating speed is 4000 rpm, and the time is 40 seconds;

[0054] Step 14: Use a photolithography machine to transfer the pattern of the double helix inductor onto the photoresist obtained in step 13, with an exposure dose of 120 mJ / cm 2 ;

[0055] Step 15, using zjx-100 developer to develop and fix the pattern on the photoresist, the developing time is 15 seconds;

[0056] Step 16: Use reactive ion beam etching technology to etch the pattern and transfer the pattern on the photoresist to the β-Ta film grown in step 11. The etching gas is CF 4 , the etching time is 90 seconds;

[0057] Step 17: Clean and remove the photoresist on the substrate obtained in step 16 to obtain a terahertz superconducting dynamic inductance detector with a hybrid structure.

[0058] Figure 2 The optical noise equivalent power of the detector is shown when the detector temperature is 60mK and the blackbody radiation power is 4.7aW. The noise equivalent power is as low as 8×10 at 10Hz. -19 W / Hz 1 / 2 .like Figure 3 As shown in the figure, after 5 hot and cold cycles, the quality factor Q and noise equivalent power NEP of the detector remain stable.

Claims

1. A superconducting dynamic inductance detector with high sensitivity and high stability, characterized in that: include: A silicon substrate and a coplanar waveguide transmission line and a hybrid structure superconducting microwave resonator made on the upper surface of the silicon substrate. The hybrid structure superconducting microwave resonator consists of a double helix inductor and a cross-finger capacitor connected in parallel. The double helix inductor is made of β-Ta film, and the cross-finger capacitor is made of α-Ta film.

2. The high-sensitivity and high-stability superconducting dynamic inductance detector according to claim 1, characterized in that: The width of the double spiral inductor is 1-5μm, and the spacing is the same as the width.

3. The high-sensitivity and high-stability superconducting dynamic inductance detector according to claim 1, characterized in that: The width of the interdigital capacitor is 1-5μm, and the interdigital spacing is the same as the width.

4. The high-sensitivity and high-stability superconducting dynamic inductance detector according to claim 1, characterized in that: The number of turns of the double spiral inductor is 10-20, and the number of interdigital indexes of the interdigital capacitor is 20-80 pairs.

5. The high-sensitivity and high-stability superconducting dynamic inductance detector according to claim 1, characterized in that: The thickness of the double spiral inductor is 20-60 μm, and the thickness of the interdigital capacitor is 100-200 μm.

6. A method for preparing a high-sensitivity and high-stability superconducting dynamic inductance detector as claimed in claim 1, characterized in that: The steps include: Step 1: Prepare a clean silicon substrate; Step 2, growing a layer of α-Ta film using a magnetron sputtering apparatus; Step 3, spin-coat a layer of AZ1500 photoresist; Step 4, using a photolithography machine to transfer the pattern of the coplanar waveguide transmission line and the interdigital capacitor to the photoresist; Step 5, using zjx-100 developer to develop and fix the pattern transferred to the photoresist; Step 6: etching the pattern using reactive ion beam etching technology to transfer the pattern on the photoresist to the α-Ta film grown in step 2; Step 7, cleaning the photoresist on the substrate obtained in step 6; Step 8, first spin-coat LOR-10B photoresist on the substrate cleaned in step 7, and then spin-coat AZ1500 photoresist; Step 9: Use a photolithography machine to expose the double-helix inductor area into a square blank area, the area size is 5-10μm larger than the inductor outline; Step 10, using zjx-100 developer to develop and fix the pattern on the photoresist; Step 11, growing a layer of β-Ta film on the substrate obtained in step 10 using a magnetron sputtering apparatus; Step 12, placing the substrate obtained in step 11 in N-methylpyrrolidone and heating it in a water bath for 5-20 hours, cleaning the photoresist spin-coated in step 8 and obtaining a β-Ta film in the double helix inductor region; Step 13, spin coating a layer of AZ1500 photoresist on the substrate obtained in step 12; Step 14, using a photolithography machine to transfer the pattern of the double spiral inductor onto the photoresist obtained in step 13; Step 15, using zjx-100 developer to develop and fix the pattern on the photoresist; Step 16, etching the pattern using reactive ion beam etching technology to transfer the pattern on the photoresist to the β-Ta film grown in step 11; Step 17, cleaning and removing the photoresist on the substrate obtained in step 16 to obtain a hybrid structure terahertz superconducting dynamic inductance detector.

7. The method for preparing a high-sensitivity and high-stability superconducting dynamic inductance detector according to claim 6, characterized in that: In step 1, high-resistance silicon is selected for the silicon substrate, and a buffered oxide etching solution is used to remove the surface oxide layer.

8. The method for preparing a high-sensitivity and high-stability superconducting dynamic inductance detector according to claim 6, characterized in that: In step 3 and step 8, the AZ1500 photoresist should be baked at 95°C for 3 minutes.

9. The method for preparing a high-sensitivity and high-stability superconducting dynamic inductance detector according to claim 6, characterized in that: In step 6 and step 16, the reactive ion beam etching uses carbon tetrafluoride as the etching gas.

10. The method for preparing a high-sensitivity and high-stability superconducting dynamic inductance detector according to claim 6, characterized in that: In step 8, the LOR-10B photoresist should be baked at 150°C for 5 minutes.

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