CN116568124A - Preparation method of Josephson junction - Google Patents
Preparation method of Josephson junction Download PDFInfo
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- CN116568124A CN116568124A CN202310725727.5A CN202310725727A CN116568124A CN 116568124 A CN116568124 A CN 116568124A CN 202310725727 A CN202310725727 A CN 202310725727A CN 116568124 A CN116568124 A CN 116568124A
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- 238000002360 preparation method Methods 0.000 title abstract description 21
- 229920002120 photoresistant polymer Polymers 0.000 claims abstract description 118
- 238000010894 electron beam technology Methods 0.000 claims abstract description 105
- 238000000034 method Methods 0.000 claims abstract description 56
- 239000000758 substrate Substances 0.000 claims abstract description 37
- 239000000463 material Substances 0.000 claims abstract description 28
- 238000000609 electron-beam lithography Methods 0.000 claims abstract description 14
- 238000001704 evaporation Methods 0.000 claims description 15
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 14
- 238000002791 soaking Methods 0.000 claims description 10
- 238000009210 therapy by ultrasound Methods 0.000 claims description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 8
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical group CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 claims description 8
- 230000008020 evaporation Effects 0.000 claims description 8
- 239000011248 coating agent Substances 0.000 claims description 5
- 238000000576 coating method Methods 0.000 claims description 5
- 238000004528 spin coating Methods 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 229940078552 o-xylene Drugs 0.000 claims description 4
- 238000001035 drying Methods 0.000 claims description 2
- 230000035945 sensitivity Effects 0.000 abstract description 7
- 239000012535 impurity Substances 0.000 abstract description 5
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 24
- 239000010410 layer Substances 0.000 description 18
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 9
- 239000004926 polymethyl methacrylate Substances 0.000 description 9
- 238000011161 development Methods 0.000 description 8
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 239000003292 glue Substances 0.000 description 5
- 239000002356 single layer Substances 0.000 description 4
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 3
- 238000005530 etching Methods 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 230000006978 adaptation Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
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- 238000001259 photo etching Methods 0.000 description 2
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- 239000000853 adhesive Substances 0.000 description 1
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- 238000003491 array Methods 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
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- 238000004090 dissolution Methods 0.000 description 1
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- 239000007888 film coating Substances 0.000 description 1
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- 230000005610 quantum mechanics Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229910052594 sapphire Inorganic materials 0.000 description 1
- 239000010980 sapphire Substances 0.000 description 1
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- 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
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- 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
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- Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
Abstract
The invention discloses a preparation method of a Josephson junction, which relates to the technical field of quantum chips and comprises the steps of arranging electron beam photoresist on the surface of a substrate; exposing the electron beam photoresist with a preset exposure dose based on electron beam lithography equipment, and forming an undercut structure in the electron beam photoresist based on forward scattering in the electron beam exposure process; developing the electron beam photoresist after exposing the electron beam photoresist, and forming a trench with an undercut structure in the electron beam photoresist; josephson junctions are prepared based on trenches with undercut structures. On the premise of only setting one layer of electron beam photoresist, an undercut structure is realized by high-dose exposure based on an overexposure mode, the overexposure ensures that the substrate has no residual photoresist, the adhesion of superconducting materials on the substrate is easier, meanwhile, impurities are reduced, and the quality factor is improved; the use of only one layer of photoresist makes the photoresist have the characteristics of high sensitivity, short exposure time, stable line width and high resolution.
Description
Technical Field
The invention relates to the technical field of quantum chips, in particular to a preparation method of a Josephson junction.
Background
Quantum computers are devices that perform information processing and computation based on quantum mechanics, and compared with classical computers, they exhibit very strong superiority in computation speed, which has marked the advent of the quantum technology era. Quantum chips are key devices for achieving quantum computing. Up to now, a great deal of research focus on superconducting qubit systems based on josephson junctions (arrays) has been widely studied due to their advantages of high gate operation fidelity, good system integration, compatibility with the mature processing technology of traditional semiconductors, and the like, so that the superconducting qubit system of the josephson junctions is one of important systems for realizing quantum computation.
Typically the josephson junctions are prepared using a lift-off process, which is typically implemented based on a bilayer glue process. In the prior art, the bilayer adhesive process is mostly prepared by using MMA (Methyl methacrylate ) +PMMA (polymethyl methacrylate, polymethyl methacrylate) photoresist, and the sensitivity and resolution of PMMA are low, so that the exposure time is long, and the line width stability and repeatability are poor. Therefore, how to provide a preparation method of the Josephson junction with stable line width and high resolution is a problem which needs to be solved by the technicians in the field.
Disclosure of Invention
The invention aims to provide a preparation method of a Josephson junction, which has stable line width and high resolution.
In order to solve the technical problems, the invention provides a preparation method of a Josephson junction, which comprises the following steps:
arranging electron beam photoresist on the surface of a substrate;
exposing the electron beam photoresist with preset exposure dose based on electron beam lithography equipment, and forming an undercut structure in the electron beam photoresist based on forward scattering in the electron beam exposure process;
developing the electron beam photoresist after exposing the electron beam photoresist, and forming a groove with an undercut structure in the electron beam photoresist;
a josephson junction is prepared based on the trench with undercut structure.
Optionally, the thickness of the electron beam photoresist is not less than 1 μm.
Optionally, on the electron beam lithography apparatus of 100kv to 125kv, the preset exposure dose is 400uc/cm 2 To 800uc/cm 2 Including endpoint values.
Optionally, disposing an electron beam photoresist on the surface of the substrate includes:
spin coating ARP6200 electron beam photoresist on the substrate;
baking the ARP6200 electron beam photoresist.
Optionally, developing the electron beam photoresist includes:
the electron beam resist was developed using o-xylene.
Optionally, preparing the josephson junction based on the trench with undercut structure comprises:
evaporating superconducting material in the grooves of the undercut structure using an electron beam;
after evaporation of the superconducting material, the electron beam photoresist is removed, and the josephson junction is fabricated.
Optionally, the coating rate of the vaporized superconducting material ranges from 1 angstrom per second to 5 angstrom per second, inclusive.
Optionally, removing the electron beam photoresist includes:
placing a sample obtained after evaporating the superconducting material into a desmutting solution for soaking for a preset time;
after the preset time, changing the solution for soaking the sample into a new photoresist removing solution, and carrying out ultrasonic treatment on the sample.
Optionally, after replacing the solution for immersing the sample with a new photoresist removing solution and performing ultrasonic treatment on the sample, the method further comprises:
the sample is soaked with acetone and sonicated.
Optionally, after the immersing the sample in acetone and subjecting the sample to ultrasonic treatment, the method further comprises:
soaking the sample with IPA and performing ultrasonic treatment on the sample;
and drying the residual IPA on the surface of the sample by using a nitrogen gun to prepare the Josephson junction. The preparation method of the Josephson junction provided by the invention comprises the following steps: arranging electron beam photoresist on the surface of a substrate; exposing the electron beam photoresist with a preset exposure dose based on electron beam lithography equipment, and forming an undercut structure in the electron beam photoresist based on forward scattering in the electron beam exposure process; developing the electron beam photoresist after exposing the electron beam photoresist, and forming a trench with an undercut structure in the electron beam photoresist; josephson junctions are prepared based on trenches with undercut structures.
On the premise of only setting one layer of electron beam photoresist, an undercut structure is realized by high-dose exposure based on an overexposure mode, the overexposure ensures that the substrate has no residual photoresist, the adhesion of superconducting materials on the substrate is easier, meanwhile, impurities are reduced, and the quality factor is improved; the use of only one layer of photoresist makes the photoresist have the characteristics of high sensitivity, short exposure time, stable line width and high resolution.
Drawings
For a clearer description of embodiments of the invention or of the prior art, the drawings that are used in the description of the embodiments or of the prior art will be briefly described, it being apparent that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained from them without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of a photoresist in the preparation of josephson junctions in the prior art;
fig. 2 to fig. 6 are process flow diagrams of a method for preparing a josephson junction according to an embodiment of the present invention;
fig. 7 to 8 are process flow diagrams of a specific method for preparing a josephson junction according to an embodiment of the present invention.
In the figure: 1. substrate, 2. Electron beam photoresist, 3. Undercut structure, 4. Trench, 5. Josephson junction.
Detailed Description
The core of the invention is to provide a preparation method of a Josephson junction. Referring to fig. 1, fig. 1 is a schematic structural diagram of a photoresist used in the preparation of josephson junctions in the prior art. Referring to fig. 1, in the prior art, a mma+pmma bilayer photoresist lithography process is used to facilitate stripping after evaporation coating, so that the junction resistor edge is more thorough and has better morphology. MMA+PMMA bilayer glue is adopted because MMA is higher in sensitivity than PMMA, and MMA is more easily dissolved by a developing solution at the same exposure dose, so that the dissolution rate of the lower MMA layer after exposure and development is faster than that of the upper PMMA layer, and an undercut structure is formed. The MMA+PMMA-based double-layer colloid system has the advantages that the undercut is large enough, the side wall of the photoresist is not easy to adhere to a junction electrode after the superconducting material is evaporated, but the defects that the PMMA resolution is not high, the photoresist is easy to deform when the photoresist is subjected to soft evaporation, and the poor development stability has larger influence on the uniformity of the size of the Josephson junction during preparation exist.
The preparation method of the Josephson junction provided by the invention comprises the following steps: arranging electron beam photoresist on the surface of a substrate; exposing the electron beam photoresist with a preset exposure dose based on electron beam lithography equipment, and forming an undercut structure in the electron beam photoresist based on forward scattering in the electron beam exposure process; developing the electron beam photoresist after exposing the electron beam photoresist, and forming a trench with an undercut structure in the electron beam photoresist; josephson junctions are prepared based on trenches with undercut structures.
Optionally, the e-beam photoresist is, for example, ARP6200 photoresist.
On the premise of only setting one layer of electron beam photoresist, an undercut structure is realized by high-dose exposure based on an overexposure mode, the overexposure ensures that the substrate has no residual photoresist, the adhesion of superconducting materials on the substrate is easier, meanwhile, impurities are reduced, and the quality factor is improved; the use of only one layer of photoresist makes the photoresist have the characteristics of high sensitivity, short exposure time, stable line width and high resolution.
Furthermore, the ARP6200 photoresist has high resolution and excellent etching resistance, so that the uniformity of line width can be better controlled in the photoetching process, in addition, a better unrecicut structure can be obtained by means of adjusting exposure dose and increasing the thickness of the photoresist, and meanwhile, the photoresist is ensured to have no residue, so that the adhesion of evaporated metal on a substrate is facilitated. Therefore, the single-layer high-resolution ARP6200 photoresist is better.
In order to better understand the aspects of the present invention, the present invention will be described in further detail with reference to the accompanying drawings and detailed description. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 2 to 6, fig. 2 to 6 are process flow diagrams of a method for preparing a josephson junction according to an embodiment of the present invention.
Referring to fig. 2, in an embodiment of the invention, the method for preparing the josephson junction comprises:
s101: an electron beam photoresist is disposed on a surface of a substrate.
The substrate 1 is a substrate 1 on which the josephson junction 5 is required, and the substrate 1 may be a sapphire substrate 1 or a gaas substrate 1, and the specific material of the substrate 1 is not particularly limited in this embodiment. The surface of the substrate 1 may be provided with a wiring structure in advance, and is not particularly limited in this embodiment as well.
Referring to fig. 3, in this step, a layer of electron beam resist 2 is provided on the surface of the substrate 1, which has been etched by electron beams in a subsequent process. The surface of the substrate 1 is provided with only one layer of electron beam photoresist 2, i.e. the photoresist layer is formed by only one material of electron beam photoresist 2. The electron beam photoresist 2 can be prepared through a multi-step spin coating process or can be prepared through a one-step process, and finally, only one layer of electron beam photoresist 2 is formed on the surface of the substrate 1.
Specifically, in the embodiment of the present invention, the thickness of the electron beam resist 2 needs to be thicker, so as to ensure that the undercut structure 3 can be formed by forward scattering during the electron beam exposure in the subsequent step. The thickness of the electron beam resist 2 is generally not less than 1 μm in the embodiment of the present invention. Of course, in the embodiment of the present invention, the thickness of the electron beam resist 2 may be less than 1 μm, so long as the undercut structure 3 with the desired morphology can be formed. For example, if the sidewall inclination angle of the trench 4 formed during the subsequent exposure and development is large, the thickness of the electron beam resist 2 in this embodiment may be less than 1 μm, i.e. the thickness of the electron beam resist 2 in this embodiment is not particularly limited.
S102: and (3) performing overexposure on the electron beam photoresist at a preset exposure dose based on the electron beam lithography equipment, and forming an undercut structure in the electron beam photoresist based on forward scattering in the electron beam exposure process.
Referring to fig. 4, in this step, the electron beam lithography apparatus is specifically used to expose the electron beam resist 2 set in the above step. The overexposure process exposes the electron beam resist 2 with a larger exposure dose, which amplifies the effect of the front scattering during the electron beam exposure process, and thus in this embodiment, an undercut structure 3, also called undercut structure, is formed in the electron beam resist 2 based on the front scattering during the electron beam exposure process. The forward scattering described above causes the photoresist cross-section to form undercut structures 3.
In order to form the undercut structure 3 in the embodiment of the present invention, the preset exposure dose is 400uc/cm on the electron beam lithography apparatus of 100kv to 125kv 2 To 800uc/cm 2 Including endpoint values. I.e. an exposure dose of 400uc/cm on a 100-125 kv electron beam lithography apparatus 2 -800uc/cm 2 . The exposure dose may form the undercut structure 3 in the electron beam resist 2, and of course, the electron beam resist 2 may be exposed with different exposure doses according to different electron beam lithography apparatuses, and the specific type of the electron beam lithography apparatus and the specific exposure dose are not particularly limited in the embodiment of the present invention.
S103: after the electron beam resist is exposed, the electron beam resist is developed, and trenches having undercut structures are made in the electron beam resist.
Referring to fig. 5, after the electron beam resist 2 is exposed as described above, the exposed electron beam resist 2 is developed in this step, thereby forming a trench 4 having an undercut structure 3 in the electron beam resist 2. Due to the overexposure process, the electron beam photoresist 2 in the undercut structure 3 is removed in this step, so that the subsequently arranged josephson junction 5 is ensured to have a higher quality factor.
S104: josephson junctions are prepared based on trenches with undercut structures.
Referring to fig. 6, in this step, a josephson junction 5 is prepared based on the trench 4 with the undercut structure 3, and the specific structure and process of the josephson junction 5 can refer to the prior art, which generally requires that a first superconducting layer, an insulating layer, and a second superconducting layer are sequentially disposed based on the trench 4 with the undercut structure 3, and finally the remaining electron beam photoresist 2 is stripped to complete the preparation of the josephson junction 5. Namely, the method specifically comprises the following steps: evaporating superconducting material in the undercut structure 3 using an electron beam; after evaporation of the superconducting material, the electron beam resist 2 is removed, producing the josephson junction 5. The above process of evaporating the superconducting material using an electron beam, i.e. the process of forming the josephson junction 5 structure, may refer to the prior art, and will not be described in detail here. The specific details of photoresist removal in this step will be described in detail in the following embodiments of the present invention, and will not be described here again.
Preferably, the electron beam photoresist 2 is, for example, ARP6200 photoresist.
According to the preparation method of the Josephson junction, provided by the embodiment of the invention, on the premise that only one layer of electron beam photoresist 2 is arranged, the undercut structure 3 is realized through high-dose exposure based on the overexposure mode, the overexposure ensures that the substrate 1 has no residual glue, the adhesion of superconducting materials on the substrate 1 is easier, meanwhile, the impurities are reduced, and the quality factor is improved; the use of only one layer of photoresist makes the photoresist have the characteristics of high sensitivity, short exposure time, stable line width and high resolution.
Furthermore, the ARP6200 photoresist has high resolution and excellent etching resistance, so that the uniformity of line width can be better controlled in the photoetching process, in addition, a better unrecicut structure can be obtained by means of adjusting exposure dose and increasing the thickness of the photoresist, and meanwhile, the photoresist is ensured to have no residue, so that the adhesion of evaporated metal on the substrate 1 is facilitated. Therefore, the single-layer high-resolution ARP6200 photoresist is better.
The details of the preparation method of the josephson junction provided by the invention are described in detail in the following examples of the invention.
Referring to fig. 7 to 8, fig. 7 to 8 are process flow diagrams of a specific josephson junction preparation method according to an embodiment of the present invention.
Referring to fig. 7, in an embodiment of the invention, the method for preparing the josephson junction comprises:
s201: ARP6200 e-beam photoresist was spin coated on the substrate.
In this step, the electron beam resist ARP6200 is spin-coated on the substrate 1, and the spin-coating speed is usually 2000rpm-5000rpm, and is usually spin-coated for about 60 seconds, so that the spin-coating of the electron beam resist 2 is completed.
It should be noted that, because the ARP6200 photoresist has high resolution and excellent etching resistance, the uniformity of the line width can be better controlled in the photolithography process, but generally the ARP6200 photoresist has better contrast, it is difficult to realize an undercut structure, which is unfavorable for stripping, or the edge morphology of the stripped junction is unfavorable, but in this embodiment, the above problems can be effectively solved by means of adjusting the exposure dose and increasing the thickness of the photoresist. The thickened electron beam photoresist 2 and a larger exposure dose can obtain a better unrecicut structure, ensure no residue of the photoresist and facilitate the adhesion of evaporated metal on a substrate. Therefore, the single-layer high-resolution ARP6200 photoresist is better.
S202: baking the electron beam photoresist.
In this step, the coated sample may be baked on a hot plate, and the baking temperature is typically 170 ℃ to 210 ℃, and is typically 5 minutes to 10 minutes, to complete the preparation of the electron beam resist 2.
S203: and (3) performing overexposure on the electron beam photoresist at a preset exposure dose based on the electron beam lithography equipment, and forming an undercut structure in the electron beam photoresist based on forward scattering in the electron beam exposure process.
The step is basically identical to S102 in the above embodiment of the present invention, and the detailed description will be omitted herein for reference to the above embodiment of the present invention.
S204: the electron beam resist was developed using o-xylene.
After the exposure in this embodiment, the development may be performed using o-xylene in this step, the temperature at the time of development is room temperature, the development time is usually 60 seconds to 90 seconds, and the undercut structure 3 is obtained after the development.
S205: an electron beam is used to evaporate the superconducting material in the trenches of the undercut structure.
Referring to fig. 8, electron Beam (EB) is used to evaporate the superconducting material in the grooves 4 of the undercut structures 3 after development in this step, and the evaporation rate of the superconducting material in this step needs to be as low as possible, and a denser film of superconducting material can be formed at a lower coating rate. The coating rate of the vaporized superconducting material in this embodiment is generally in the range of 1 angstrom per second to 5 angstrom per second, inclusive. The film coating rate can ensure that the obtained superconducting material film layer has higher compactness.
In this step it is generally necessary to use electron beam oblique evaporation of the superconducting material to form josephson junctions 5 in the undercut structures 3.
S206: and (3) immersing the sample obtained after evaporating the superconducting material in the desmear solution for a preset time.
After evaporation of the superconducting material, the resulting sample is immersed in a photoresist stripping solution such as methylpyrrolidone (NMP) or photoresist stripping solution RemoverPG, typically heated to about 85 ℃ for about 1 hour.
S207: after a preset time, the solution for soaking the sample is replaced by a new photoresist removing solution, and the sample is subjected to ultrasonic treatment.
After the preset time of soaking, the photoresist removing solution of the soaking sample described in S206 is replaced in this step, that is, the solution of the soaking sample is updated, the photoresist removing solution such as methyl pyrrolidone or photoresist removing solution RemoverPG used for a period of time is replaced with a new photoresist removing solution which is not used, and the ultrasonic treatment is performed in the new photoresist removing solution for about 5 minutes, so as to ensure that the residual electron beam photoresist 2 on the surface of the substrate 1 is removed.
S208: the sample is soaked with acetone and sonicated.
In this step, the sample after photoresist removal is soaked in acetone, and the sample is subjected to ultrasonic treatment in acetone for about 5 minutes, so that the sample after photoresist removal is further cleaned.
S209: the sample was soaked with IPA and sonicated.
In this step, the acetone-washed sample is immersed in an IPA (isopropyl alcohol) solution, and the sample is sonicated in the IPA solution for about 5 minutes, so that the sample is finally dried.
S210: the residual IPA on the surface of the sample was dried using a nitrogen gun to make Josephson junctions.
In this step, the sample taken out of the IPA solution was dried using a nitrogen gun, and the sample was dried to complete the preparation of josephson junction 5.
The preparation method of the Josephson junction provided by the embodiment of the invention adopts a single-layer glue process, and simultaneously simplifies the process flow, wherein overexposure ensures that the substrate 1 has no residual glue, is easier for adhesion of superconducting materials on the substrate 1, reduces impurities and improves the quality factor; the use of only one layer of photoresist makes the photoresist have the characteristics of high sensitivity, short exposure time, stable line width and high resolution.
In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, so that the same or similar parts between the embodiments are referred to each other.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative elements and steps are described above generally in terms of functionality in order to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software modules may be disposed in Random Access Memory (RAM), memory, read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
Finally, it is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The preparation method of the Josephson junction provided by the invention is described in detail. The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to facilitate an understanding of the method of the present invention and its core ideas. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims.
Claims (10)
1. A method of preparing a josephson junction comprising:
arranging electron beam photoresist on the surface of a substrate;
exposing the electron beam photoresist with preset exposure dose based on electron beam lithography equipment, and forming an undercut structure in the electron beam photoresist based on forward scattering in the electron beam exposure process;
developing the electron beam photoresist after exposing the electron beam photoresist, and forming a groove with an undercut structure in the electron beam photoresist;
a josephson junction is prepared based on the trench with undercut structure.
2. The method of claim 1, wherein the thickness of the e-beam photoresist is not less than 1 μm.
3. The method according to claim 1, wherein the preset exposure dose is 400uc/cm on the electron beam lithography apparatus of 100kv to 125kv 2 To 800uc/cm 2 Including endpoint values.
4. A method according to any one of claims 1 to 3, wherein said disposing an electron beam photoresist on the surface of the substrate comprises:
spin coating ARP6200 electron beam photoresist on the substrate;
baking the ARP6200 electron beam photoresist.
5. The method of claim 1, wherein developing the e-beam photoresist comprises:
the electron beam resist was developed using o-xylene.
6. The method of claim 1, wherein preparing a josephson junction based on the trench with undercut structure comprises:
evaporating superconducting material in the grooves of the undercut structure using an electron beam;
after evaporation of the superconducting material, the electron beam photoresist is removed, and the josephson junction is fabricated.
7. The method of claim 6, wherein the vapor superconducting material has a coating rate ranging from 1 angstrom per second to 5 angstrom per second, inclusive.
8. The method of claim 6, wherein removing the electron beam photoresist comprises:
placing a sample obtained after evaporating the superconducting material into a desmutting solution for soaking for a preset time;
after the preset time, changing the solution for soaking the sample into a new photoresist removing solution, and carrying out ultrasonic treatment on the sample.
9. The method of claim 8, further comprising, after replacing the solution in which the sample is immersed with a new photoresist removing solution and sonicating the sample:
the sample is soaked with acetone and sonicated.
10. The method of claim 9, further comprising, after said immersing said sample in acetone and sonicating said sample:
soaking the sample with IPA and performing ultrasonic treatment on the sample;
and drying the residual IPA on the surface of the sample by using a nitrogen gun to prepare the Josephson junction.
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