A method for manufacturing a semiconductor superconductor composite device and a semiconductor superconductor composite device

Abstract

The application provides a preparation and interface modification method of a semiconductor composite device. A semiconductor superconducting composite device is also provided. By using a general high-quality composite device micro-nano processing method and by controlling etching time to change interface properties, the micro-nano processing includes an electron beam exposure system, a plasma etching system and a coating system. The morphology shows that a clean device is prepared, a transmission electron microscope image shows that a thin film material is epitaxially grown on a semiconductor nanowire surface, transport data observes a quantized conductance platform, and a very high transmission coefficient is obtained by data fitting. These all show a high-quality device. The inventor observes that an etching-induced interface band bending increases a carrier concentration. The above shows that the process flow is suitable for different types of devices, can deposit different materials, form thin films with different thicknesses, and can also change interface properties by etching. It provides a solid foundation for the preparation and research of composite devices in the future.

Description

Technical Field

[0001] This invention belongs to the field of composite device fabrication, specifically relating to a method for preparing a semiconductor composite device and a semiconductor superconducting composite device thereof. Background Technology

[0002] In the field of composite device research, the fabrication of composite devices is fundamental. Composite devices composed of different materials exhibit a variety of fascinating physical phenomena. Different device structures also exhibit different phenomena, allowing for the study of different properties and driving progress in both fundamental scientific research and device application research. For example, theory predicts that composite devices of strongly spin-orbit coupled semiconductor nanowires and superconductors can enter topological regions under parallel magnetic fields, exhibiting Majorana zero modes at their endpoints, which can be used for topological quantum computing. The fabrication of composite devices is of great significance for both fundamental scientific research and future applications.

[0003] Currently, the fabrication of high-quality semiconductor superconducting composite devices involves two main methods: nanowire masking for superconducting thin film growth and smart wall technology for composite device processing. Both methods avoid the use of photoresist during device fabrication, resulting in clean interfaces and high-quality composite devices. However, both methods have significant limitations and are inconvenient to use. The first method utilizes nanowire or nanosheet masking. With nanowire masking, single or double junctions can be fabricated during superconducting thin film growth. Nanowire masking allows some nanowires to remain uncovered by the superconducting film. This method is limited to devices with simple structures and requires finding suitable nanowires to mask on the substrate after growth. Within a batch of devices, the interface properties are generally consistent, making it difficult to obtain devices with different interfaces. The second method utilizes smart wall masking. This involves artificially constructing complex insulating structures as masking materials to form the device during superconducting thin film deposition. Because the structure can be constructed using common Wiener processing methods, relatively complex devices can be fabricated. However, each device requires individually designed smart walls and optimized processes. This method is inflexible, and changing device types requires significant work. Therefore, this invention utilizes relatively common micro-nano fabrication methods to fabricate composite devices. The process can be extended to different types of devices, various coating methods, and can handle interfaces. Summary of the Invention

[0004] Therefore, the purpose of this invention is to overcome the defects in the prior art and provide a method for preparing a semiconductor composite device and a semiconductor superconducting composite device thereof, so as to solve the problems that the existing composite device manufacturing methods are not flexible and universal and that the interface properties cannot be flexibly changed during the process.

[0005] Before describing the content of this invention, the following terms are defined as follows:

[0006] The term "PMMA" refers to polymethyl methacrylate.

[0007] The term "Vbias" refers to the bias voltage.

[0008] The term "back gate" refers to a gate with an insulating substrate as the dielectric.

[0009] The term "MIBK" refers to methyl isobutyl ketone.

[0010] The term "IPA" refers to isopropanol.

[0011] The term "xylene" refers to xylene.

[0012] The term "p-dioxane" refers to 1,4-dioxane.

[0013] The term "MIAK" refers to methyl isopentyl ketone.

[0014] The term "2-pentanone" refers to 2-pentanone.

[0015] The term "MEK" refers to methyl ethyl ketone.

[0016] The term "ethanol" refers to ethanol.

[0017] The term "TMAH" refers to tetramethylammonium hydroxide.

[0018] The term "DI" refers to deionized water.

[0019] The term "ZEP" refers to: styrene methacrylate group.

[0020] The term "EBR-9" refers to electron beam lithography, the ninth generation of photoresist.

[0021] The term "HSQ" refers to hydrosilicates.

[0022] The term "COP" refers to: epoxy polymer

[0023] The term "PBS" refers to polyisobutylene sulfur dioxide phosphate buffer solution.

[0024] To achieve the above objectives, a first aspect of the present invention provides a method for fabricating a semiconductor composite device, wherein the method fabricates the semiconductor composite device using micro / nano fabrication methods and performs interface modification by controlling the micro / nano fabrication steps; wherein,

[0025] The micro / nano fabrication method is selected from one or more of the following: electron beam lithography, plasma etching, and thin film deposition;

[0026] Preferably, the thin film deposition method is selected from one or more of the following: electron beam evaporation, magnetron sputtering, and resistance thermal evaporation.

[0027] According to a preparation method of a first aspect of the present invention, the preparation method includes the following steps:

[0028] (1) Design the exposure pattern for semiconductor composite devices;

[0029] (2) Based on step (1), perform exposure and development;

[0030] (3) Based on step (2), etch the interface of the semiconductor material;

[0031] (4) Deposit a thin film based on step (3);

[0032] (5) Remove the adhesive and peel off the excess film to obtain the semiconductor composite device;

[0033] Preferably, interface modification is performed by controlling the etching conditions in step (3).

[0034] According to the preparation method of the first aspect of the present invention, in step (1), before designing the exposure pattern of the semiconductor material, the method further includes: spin-coating photoresist on a substrate carrying the semiconductor material and baking it;

[0035] Preferably, the baking time is 1 to 15 minutes, more preferably 1 to 5 minutes, and even more preferably 1 to 3 minutes;

[0036] Preferably, the photoresist is selected from one or more of the following: PMMA, ZEP, EBR-9, HSQ, PBS, COP; more preferably, it is selected from one or more of the following: PMMA, ZEP, EBR-9, PBS; and even more preferably, it is PMMA or ZEP; and / or

[0037] Preferably, the substrate is selected from one or more of the following: SiO2, Si3N4, intrinsic silicon, sapphire, GaN, mica sheet, quartz glass; more preferably, it is selected from one or more of the following: SiO2, Si3N4, intrinsic silicon, sapphire, GaN; and even more preferably, it is selected from one or more of the following: SiO2, intrinsic silicon, sapphire.

[0038] According to the preparation method of the first aspect of the present invention, in step (2), the pattern designed in step (1) is exposed and developed by an electron beam exposure system;

[0039] Preferably, the composite device structure is defined by the electron beam exposure system, and its structural width and positional accuracy are both less than 100 nm, more preferably less than 90 nm, even more preferably less than 70 nm, and even more preferably less than 50 nm.

[0040] Preferably, the developer is selected from one or more of the following: MIBK:IPA mixed solution, xylene:p-dioxane mixed solution, MIAK:2-pentanone mixed solution, MEK:ethanol mixed solution, TMAH:DI mixed solution, more preferably selected from one or more of the following: MIBK / IPA mixed solution, xylene / p-dioxane mixed solution, MIAK / 2-pentanone mixed solution, and even more preferably: MIBK:IPA mixed solution or xylene:p-dioxane mixed solution;

[0041] Preferably, the development time is 30–600 s, more preferably 30–300 s, and even more preferably 30–180 s; and / or

[0042] Preferably, the exposure time is 1 to 300 s, more preferably 1 to 180 s, and even more preferably 1 to 60 s.

[0043] According to the preparation method of the first aspect of the present invention, in step (3), the adsorbed atoms and oxide layer on the surface of the semiconductor material are removed by a plasma etching system, and the interface properties are changed.

[0044] According to the preparation method of the first aspect of the present invention, in step (3),

[0045] The etching time is 5 to 600 s, preferably 5 to 240 s, and more preferably 5 to 120 s;

[0046] The etching gas is selected from one or more of the following: Ar, O2, CF4, SF6, NF3, SiCl4, CH4, H2, preferably selected from one or more of the following: Ar, O2, CF4, SF6, NF3, SiCl4, more preferably selected from one or more of the following: Ar, O2, CF4, SF6;

[0047] The etching pressure is ≤10Pa, preferably ≤8Pa, and more preferably ≤5Pa;

[0048] The etching ion beam current is ≥10mA, preferably ≥15mA, more preferably ≥20mA; and / or

[0049] The etching ion beam voltage is ≤1000V, preferably ≤800V, and more preferably ≤600V.

[0050] According to the preparation method of the first aspect of the present invention, in step (4), the film is transferred to the thin film deposition chamber by vacuum to avoid exposure to the atmosphere and causing surface adsorption or secondary oxidation at the interface; wherein the thin film is a metal thin film;

[0051] Preferably, the material of the thin film is selected from one or more of the following: aluminum, lead, niobium titanium nitride, tin; more preferably, it is selected from one or more of the following: aluminum, lead, niobium titanium nitride; and even more preferably, aluminum or lead; and / or

[0052] Preferably, step (4) further includes using a cold substrate to improve the quality of the deposited film.

[0053] According to the preparation method of the first aspect of the present invention, in step (4), a transition layer is deposited to prevent direct oxidation of the interface, and then the material is transferred to a thin film deposition device for thin film deposition; wherein the thin film is a metal thin film;

[0054] Preferably, the material of the thin film is selected from one or more of the following: aluminum, lead, niobium titanium nitride, tin; more preferably, it is selected from one or more of the following: aluminum, lead, niobium titanium nitride; and even more preferably, aluminum or lead; and / or

[0055] Preferably, step (4) further includes using a cold substrate to improve the quality of the deposited film.

[0056] According to the preparation method of the first aspect of the present invention, in step (5), the sample after the thin film is deposited is placed in a desizing solution to peel off the excess film, thereby obtaining the semiconductor composite device;

[0057] Preferably, the adhesive remover solution is selected from one or more of the following: acetone, methyl isobutyl ketone, butyl acetate, dimethylformamide, dichloromethane, propylene glycol monomethyl ether acetate, trichloroethylene, N-methylpyrrolidone, methyl ethyl ketone; more preferably selected from one or more of the following: acetone, methyl isopropanone, butyl acetate, dimethylformamide, propylene glycol monomethyl ether acetate, trichloroethylene; and even more preferably selected from one or more of the following: acetone, methyl isopropanone, butyl acetate, dimethylformamide, propylene glycol monomethyl ether acetate; and / or

[0058] Preferably, the auxiliary method for removing adhesive is selected from one or more of the following: dropper blowing, air gun blowing, ultrasonic vibration.

[0059] A second aspect of the present invention provides a semiconductor superconducting composite device, which is prepared according to the preparation method described in the first aspect.

[0060] According to a specific embodiment of the present invention, the general method for fabricating high-quality semiconductor superconducting composite devices and adjusting interface properties uses a general micro / nano fabrication method to fabricate the composite device, and the interface properties are adjusted through etching in one step. The method includes the following steps:

[0061] (1) Define the pattern of the composite device using an electron beam exposure system;

[0062] (2) Use etching to remove the oxide layer of semiconductor materials and modify the interface.

[0063] (3) Use thin film deposition technology to deposit upper layer materials and fabricate composite devices.

[0064] (4) Use solvent to remove adhesive and peel off excess film to obtain the desired composite device.

[0065] Step (1) graphical definition includes the following steps:

[0066] (1) Spin-coating photoresist onto a substrate containing semiconductor material.

[0067] (2) Use an e-book exposure system to expose the photoresist according to the required pattern.

[0068] (3) Develop the exposed substrate to obtain the desired pattern.

[0069] The method for preparing the etched surface in step (2) is to generate plasma using a certain pressure gas, apply voltage to guide the plasma to bombard the sample surface, remove the surface oxide layer and change the interface properties.

[0070] The thin film deposition preparation method described in step (3) involves vacuum transfer to the thin film deposition chamber to avoid exposure to the atmosphere and subsequent surface adsorption or secondary oxidation at the interface. Alternatively, a transition layer deposition method can be used to prevent direct oxidation at the interface. The film is then transferred to a thin film deposition apparatus for deposition.

[0071] The solvent removal method described in step (4) involves selecting a removal solvent based on the type of adhesive and using methods such as dropper blowing, air gun blowing, or ultrasonic vibration to remove excess film.

[0072] According to another specific embodiment of the present invention, the method integrates a universal Wiener processing approach, utilizing an electron beam lithography system, a plasma etching system, and a thin film deposition system. The thin film deposition system includes, but is not limited to, electron beam evaporation deposition systems and magnetron sputtering deposition systems. Furthermore, a cold substrate can be added to the deposition system. This achieves the processing and interface property modification of different types of high-quality composite devices under similar process conditions. The electron beam lithography system can define the composite device structure with high precision, with structural width and positional accuracy less than 100 nm. The plasma etching system can utilize different gases to generate plasma. Taking argon as an example, the plasma is generally electrically neutral, but electrons in Ar atoms detach from the atoms, giving the atoms a positive charge. Under voltage, this charge can accelerate and physically bombard the surface of the etched material, achieving the purpose of removing adsorbed atoms and oxide layers. The electron beam evaporation deposition system utilizes electron bombardment of the metal material and heating it to melt. After evaporation, the material is adsorbed onto the substrate surface to form a thin film. In magnetron sputtering coating systems, a negative voltage is applied to the target material, and an inert gas is injected into the cavity. High voltage accelerates electrons, which then undergo cyclotron motion under the influence of a magnetic field, increasing their trajectory and causing them to collide with and electrify argon atoms, generating plasma. The atoms become positively charged and bombard the target material under negative pressure, causing sputtered target material clusters to fall onto the substrate to form a thin film. These versatile Wiener processing methods make the developed techniques more widely applicable.

[0073] To address the limitations of existing composite device fabrication methods in terms of flexibility and versatility, and the inability to flexibly modify interface properties during the process, this invention aims to develop a method for fabricating high-quality composite devices based on the traditional Wiener process, enabling the modification of interface properties through etching. This micro-nano fabrication method combines electron beam lithography, plasma etching, and thin film deposition techniques, achieving universal composite device fabrication and interface property modification through process optimization. Due to the versatility of the Wiener process, this method can fabricate different types of composite devices with fewer limitations, allowing for variations in thin film types and thicknesses, and enabling low-temperature thin film evaporation. It has achieved the fabrication of various high-quality composite devices under similar process conditions, providing a foundation for future research using different devices in different fields.

[0074] The method for fabricating and modifying the interface of the semiconductor composite device of the present invention may have, but is not limited to, the following beneficial effects:

[0075] 1. Compared with fabricating composite devices using nanowires for masking, this method can fabricate complex composite devices. Different composite devices can be fabricated simply by changing the exposure pattern and making fine adjustments. Different types and thicknesses of metal thin films can be obtained by changing different coating sources, and the interface properties can be flexibly changed by etching.

[0076] 2. Compared with the use of smart wall technology to produce high-quality devices, this technology has better process conditions and can be easily transferred to other similar types of devices. It is relatively simple to manufacture and can produce more complex devices.

[0077] 3. The general high-quality composite device micro / nano fabrication method provided by this invention can modify interface properties by controlling the etching time. This process employs general micro / nano fabrication techniques, including electron beam evaporation, plasma etching, and deposition systems. Utilizing the high precision of electron beam evaporation, both small structures and precise overlays can be fabricated, enabling the creation of complex devices. Plasma etching can remove adsorbed gases and oxide layers from the semiconductor material surface and modify interface properties. The deposition system, which can be electron beam evaporation or magnetron sputtering, can deposit metal thin films of different metals and thicknesses. A cold substrate can be used to further improve film quality. We fabricated different types of devices, depositing thin films of different metals and thicknesses. We also deposited exceptionally thin films using a cold substrate. Morphological analysis revealed clean devices, transmission electron microscopy images showed epitaxial growth of the thin film material on the semiconductor nanowire surface, transport data observed a quantized conductivity plateau, and data fitting yielded a high transmission coefficient. All of these indicate high-quality devices. Furthermore, we observed an increase in carrier concentration due to interfacial band bending induced by etching. This demonstrates that this process is applicable to different types of devices, can deposit different materials, and form thin films of varying thicknesses. It also allows for the alteration of interfacial properties through etching. This provides a solid foundation for future fabrication and research of composite devices. Attached Figure Description

[0078] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings, wherein:

[0079] Figure 1 A scanning electron microscope image of the composite device of nanowires and thick aluminum prepared in Example 1 of the present invention is shown.

[0080] Figure 2 A scanning electron microscope image of the composite device of nanowires and thin lead prepared in Example 2 of the present invention is shown.

[0081] Figure 3 The image shows a transmission electron microscope image of the interface between the nanowire and thick aluminum composite device prepared in Example 1 of the present invention.

[0082] Figure 4 The diagram shows the transport data and fitting results of the composite device of nanowires and thick aluminum in Embodiment 3 of the present invention; wherein, Figure 4(b), 4(c), and 4(d) show the changes in conductivity of the device after 20s, 40s, and 2min of interface etching, respectively, with respect to the bias voltage Vbias and the back gate voltage (Vbg). It can be seen that aluminum induces a superconducting bandgap of about 0.2meV in the nanowire. Figure 4 (a) The figure above shows the transverse cutoff lines outside the superconducting bandgap for the three devices, representing the change in conductance with the back gate. On one hand, quantized conductance plateaus can be seen in all three curves, reflecting the ballistic transport properties of the conductive channels. On the other hand, by fitting the conductance versus bias voltage curves under different back gates, the corresponding number of conductive channels and the transmission coefficient of each channel can be obtained. Figure 4 (a) The inset in the above figure is an example; circles represent data, and triangles represent fitted curves. The corresponding results for the three devices are as follows: Figure 4 (a) As shown in the three figures below, it can be seen that the number of conductive channels gradually increases or decreases with the increase of the back-gate voltage, and the transmission coefficient of the conductive channels rapidly increases to 1, which also reflects the high quality of the device. On the other hand, under the same back-gate voltage, the conductivity increases with the increase of the device etching time. This is because etching causes band bending at the interface; the longer the etching time, the more severe the band bending, the more electrons accumulate, and the greater the conductivity. Charge accumulation at the interface is conducive to the occurrence of the superconducting proximity effect, which is the effect of etching on the interface.

[0083] Figure 5 A flowchart of the method for fabricating and modifying the interface of the semiconductor composite device of the present invention is shown. Detailed Implementation

[0084] The present invention will be further illustrated below with specific embodiments. However, it should be understood that these embodiments are merely for more detailed and specific illustration and should not be construed as limiting the present invention in any way.

[0085] This section provides a general description of the materials and testing methods used in the experiments of this invention. While many of the materials and methods of operation used to achieve the objectives of this invention are well known in the art, the invention is still described in as much detail as possible herein. It will be apparent to those skilled in the art that, unless otherwise stated in the context, the materials and methods of operation used in this invention are well known in the art.

[0086] The reagents and instruments used in the following examples are as follows:

[0087] Reagents:

[0088] PMMA, purchased from MicroChem;

[0089] Acetone and isopropanol were purchased from Beijing Tongguang Fine Chemical Company.

[0090] The developer, a 1:3 mixture of methyl isobutyl ketone (MIBK) and isopropanol (IPA), was purchased from Kayaku Advanced Materials Co., Ltd.

[0091] instrument:

[0092] The thermal field emission scanning electron microscope, model 5-OR100-EOC, was purchased from Raith GmbH.

[0093] The ultra-high vacuum electron beam multi-cavity evaporation coating system was purchased from PLASSYS BESTEK SAS, model MEB550SL3.

[0094] The radio frequency magnetron sputtering coating machine, model JSD500, was purchased from Beijing Dongfang Gaide Vacuum Technology Co., Ltd.

[0095] Example 1

[0096] This embodiment illustrates the method for fabricating and modifying the interface of the semiconductor composite device of the present invention.

[0097] This embodiment uses semiconductor nanowires and thick aluminum as examples, and the specific preparation steps are as follows:

[0098] Step 1: Spin-coating photoresist. A suitable photoresist is spin-coated onto the substrate containing nanowires. The selection of the photoresist depends on the required thickness and precision. The substrate is then vitrified by baking. If necessary, a vacuum pump can be used to remove the solvent. For the nanowire material, we use a positive photoresist. Based on the required precision, we choose polymethyl methacrylate (PMMA). Depending on the structural requirements, etching time, and metal film thickness, different concentrations of photoresist can be used to obtain photoresist of varying thicknesses after spin-coating. The required exposure voltage, dosage, and pattern design are then explored to meet experimental requirements. In this example, the substrate used is a 300nm thick SiO2 silicon wafer (5mm in length and width), the photoresist is polymethyl methacrylate (PMMA), the baking temperature is 180℃, and the baking time is 3 minutes.

[0099] Step 2: Electron Beam Exposure and Development. Design the exposure pattern according to the required composite device, select an appropriate accelerating voltage and dose, and expose the pattern. After exposure, develop the exposed photoresist using the corresponding developer. In this embodiment, the accelerating voltage is 20kV and the dose is 260μC / cm². 2The developer is a mixture of methyl isobutyl ketone (MIBK) and isopropanol (IPA) in a volume ratio of 1:3, with a development time of 3 minutes. The fixer is isopropanol, with a fixing time of 1 minute.

[0100] Step 3: Etching and Deposition. Etching involves selecting multiple parameters, including gas, pressure, power, and accelerating voltage. By varying these conditions, the subsequent morphology of the composite device and measurement results are used to optimize the parameters and summarize the impact of etching on the interface. After evacuating the sample into the etching chamber, appropriate etching gas, pressure, plasma power, and accelerating voltage are selected to etch the nanowire contact interface. The impact of etching on the oxide layer and interface is also investigated. After etching, the sample is transferred to the deposition chamber under vacuum to deposit a metal thin film. When using other deposition systems, after etching, the sample is quickly transferred to another deposition system for metal thin film deposition. If necessary, a small amount of Ti metal can be deposited in the deposition chamber after the etching system is transferred to prevent direct oxidation of the semiconductor nanowires, which could affect the interface. In this embodiment, the etching gas used is argon, with a pressure of 0.03 Pa, an ion beam current of 10 mA, and an ion beam voltage of 260 V. The etching time is 40 seconds. In this embodiment, after etching, the sample is transferred to the deposition chamber under vacuum to deposit a thick aluminum metal thin film.

[0101] Step 4: Resin Removal. The coated substrate is immersed in a resist removal solution, such as acetone, to remove excess film and form a composite device. For more complex devices, the above steps can be repeated to deposit other materials and combine devices. In this embodiment, acetone is used as the resist removal solution.

[0102] The determination of this process method requires exploring and determining the parameters of each step based on actual conditions, such as substrate material, electrode thickness, oxide layer thickness, etc., and then promoting the device type and thin film material.

[0103] Figure 1 The image shows a scanning electron microscope image of a composite device of nanowires and thick aluminum fabricated using this method. After etching, the sample was directly transferred to the coating vacuum chamber to evaporate a thin metal film.

[0104] Figure 3 The image shows a transmission electron microscope (TEM) image of the interface between the nanowire and thick aluminum composite device prepared in Example 1 of this invention. We can see that the aluminum is a single crystal and is epitaxially grown at the interface, demonstrating the high quality of the device fabricated using this process.

[0105] Example 2

[0106] This embodiment illustrates the method for fabricating and modifying the interface of the semiconductor composite device of the present invention.

[0107] This embodiment uses semiconductor nanowires and thin lead as examples, and the specific preparation steps are as follows:

[0108] Step 1: Spin-coating photoresist. A suitable photoresist is spin-coated onto the substrate containing nanowires. The selection of the photoresist depends on the required thickness and precision. The substrate is then vitrified by baking. If necessary, a vacuum pump can be used to remove the solvent. For the nanowire material, we use a positive photoresist. Based on the required precision, we choose polymethyl methacrylate (PMMA). Depending on the structural requirements, etching time, and metal film thickness, different concentrations of photoresist can be used to obtain photoresist of varying thicknesses after spin-coating. The necessary exposure voltage, dosage, and pattern design are then determined to meet experimental requirements. In this example, the substrate used is a 300nm thick SiO2 silicon wafer (5mm in length and width), and the photoresist is polymethyl methacrylate (PMMA).

[0109] Step 2: Electron Beam Exposure and Development. Design the exposure pattern according to the required composite device, select an appropriate accelerating voltage and dose, and expose the pattern. After exposure, develop the exposed photoresist using the corresponding developer. In this embodiment, the accelerating voltage is 20kV and the dose is 260μC / cm². 2 The developer is a 1:3 mixture of methyl isobutyl ketone (MIBK) and isopropanol (IPA), with a development time of 3 minutes. The fixer is isopropanol, with a fixing time of 1 minute.

[0110] Step 3: Etching and Deposition. Etching involves selecting multiple parameters, including gas, pressure, power, and accelerating voltage. By varying these conditions and analyzing the subsequent morphology and measurement results of the composite device, the parameters are optimized, and the impact of etching on the interface is summarized. After evacuating the sample into the etching chamber, appropriate etching gas, pressure, plasma power, and accelerating voltage are selected to etch the nanowire contact interface. The impact of etching on the oxide layer and interface is also investigated. After etching, the sample is transferred to the deposition chamber under vacuum to deposit a metal thin film. When using other deposition systems, after etching, the sample is quickly transferred to another deposition system for metal thin film deposition. If necessary, a small amount of Ti metal can be deposited in the deposition chamber after transferring the sample from the etching system to prevent direct oxidation of the semiconductor nanowires, which could affect the interface. In this embodiment, the etching gas used is argon, with a pressure of 0.03 Pa, an ion beam current of 10 mA, and an ion beam voltage of 260 V. The etching time is 4 minutes. After etching, the sample in this embodiment was transferred to the deposition chamber in the etching system to deposit a small amount of titanium metal to prevent direct oxidation of the semiconductor nanowires and their impact on the interface. It was then rapidly transferred to magnetron sputtering, where a thin lead metal film was deposited using a cold substrate. It can be seen that the device morphology is excellent, and the junction spacing is very small. The two devices prepared in Examples 1 and 2 are of different types, with different metals deposited and significant differences in thickness, demonstrating the versatility of this process method.

[0111] Step 4: Resin Removal. The coated substrate is immersed in a resist removal solution, such as acetone, to remove excess film and form a composite device. For more complex devices, the above steps can be repeated to deposit other materials and combine devices. In this embodiment, acetone is used as the resist removal solution.

[0112] The determination of this process method requires exploring and determining the parameters of each step based on actual conditions, such as substrate material, electrode thickness, oxide layer thickness, etc., and then promoting the device type and thin film material.

[0113] Figure 2 The image shows a composite device made of nanowires and thin lead using this method. After etching, the sample was rapidly transferred to magnetron sputtering, where a thin lead metal film was deposited using a cold substrate. It can be seen that the device morphology is excellent, with a very small junction spacing. The two devices belong to different types of devices, with different metals deposited and significant differences in thickness, demonstrating the versatility of this process method.

[0114] Example 3

[0115] This embodiment is used to illustrate the transport data and fitting results of the composite device of nanowires and thick aluminum prepared in Example 1 of the present invention.

[0116] (1) The composite device of nanowires and thick aluminum with different etching times was placed in a low temperature thermostat and cooled to a minimum temperature of around 10mK.

[0117] (2) Measure the two-dimensional graph data of differential conductance as a function of bias voltage and back door voltage using AC phase-locked loop technology.

[0118] (3) The number of conductive channels and the transmission coefficient of the corresponding channels are obtained by fitting the curve of the differential conductance with the bias voltage through the short junction scattering model.

[0119] Figure 4 The diagram shows the transport data and fitting results of the composite device of nanowires and thick aluminum in Embodiment 3 of the present invention; wherein, Figure 4 (b), 4(c), and 4(d) show the conductivity of the device after 20s, 40s, and 2min of interface etching, respectively, as a function of the bias voltage Vbias and the back gate. It can be seen that aluminum induces a superconducting gap of about 0.2meV in the nanowire. Figure 4 (a) The figure above shows the transverse cutoff lines outside the superconducting bandgap for the three devices, representing the change in conductance with the back gate. On one hand, quantized conductance plateaus can be seen in all three curves, reflecting the ballistic transport properties of the conductive channels. On the other hand, by fitting the conductance versus bias voltage curves under different back gates, the corresponding number of conductive channels and the transmission coefficient of each channel can be obtained. Figure 4 (a) The inset in the above figure is an example; the circles represent data, and the triangles represent fitted curves. The corresponding results for the three devices are as follows: Figure 4 (a) As shown in the three figures below, it can be seen that the number of conductive channels gradually increases or decreases with the increase of the back-gate voltage, and the transmission coefficient of the conductive channels rapidly increases to 1, which also reflects the high quality of the device. On the other hand, under the same back-gate voltage, the conductivity increases with the increase of the device etching time. This is because etching causes band bending at the interface; the longer the etching time, the more severe the band bending, the more electrons accumulate, and the greater the conductivity. Charge accumulation at the interface is conducive to the occurrence of the superconducting proximity effect, which is the effect of etching on the interface.

[0120] The above demonstrates that this process can fabricate different types of devices, use different types and thicknesses of metal materials, and change the interface properties by altering the etching time.

[0121] As research progresses, studies on various properties within the same material become necessary, requiring different device types, material properties, and interface variations. This universal approach and interface treatment undoubtedly make the research more convenient.

[0122] Although the invention has been described to a certain extent, it is apparent that appropriate variations can be made to the various conditions without departing from the spirit and scope of the invention. It is understood that the invention is not limited to the described embodiments, but falls within the scope of the claims, which include equivalent substitutions for each of the elements.

Claims

1. A method for fabricating a semiconductor composite device, characterized in that, The fabrication method uses micro-nano fabrication to prepare semiconductor composite devices and modifies the interface by controlling the micro-nano fabrication steps; wherein the micro-nano fabrication method is selected from one or more of the following: electron beam lithography, plasma etching, and thin film deposition; The preparation method includes the following steps: (1) Designing the exposure pattern for semiconductor composite devices; (2) Based on step (1), perform exposure and development; (3) Based on step (2), the interface of the semiconductor material is etched. The adsorbed atoms and oxide layer on the surface of the semiconductor material are removed by plasma etching system, and the interface properties are changed. (4) Deposit a thin film based on step (3); (5) Remove the adhesive and peel off the excess film to obtain the semiconductor composite device; Furthermore, in step (3), the etching time is 5~600s, the etching gas is selected from one or more of the following: Ar, O2, CF4, SF6, NF3, SiCl4, CH4, H2; the etching gas pressure is ≤10Pa, the etching ion beam current is ≥10mA, and the etching ion beam voltage is ≤1000V.

2. The preparation method according to claim 1, characterized in that, The thin film deposition method is selected from one or more of the following: electron beam evaporation, magnetron sputtering, and resistance thermal evaporation.

3. The preparation method according to claim 1 or 2, characterized in that, In step (1), before designing the exposure pattern of the semiconductor material, the method further includes: spin-coating photoresist on a substrate carrying the semiconductor material and baking it; Preferably, the baking time is 1-15 minutes, more preferably 1-5 minutes, and even more preferably 1-3 minutes; Preferably, the photoresist is selected from one or more of the following: PMMA, ZEP, EBR-9, HSQ, PBS, COP; more preferably, it is selected from one or more of the following: PMMA, ZEP, EBR-9, PBS; and even more preferably, PMMA or ZEP; and / or Preferably, the substrate is selected from one or more of the following: SiO2, Si3N4, intrinsic silicon, sapphire, GaN, mica sheet, quartz glass; more preferably, it is selected from one or more of the following: SiO2, Si3N4, intrinsic silicon, sapphire, GaN; and even more preferably, it is selected from one or more of the following: SiO2, intrinsic silicon, sapphire.

4. The preparation method according to any one of claims 1 to 3, characterized in that, In step (2), the pattern designed in step (1) is exposed and developed using an electron beam exposure system. Preferably, the composite device structure is defined by the electron beam exposure system, and its structural width and positional accuracy are both less than 100 nm, more preferably less than 90 nm, even more preferably less than 70 nm, and even more preferably less than 50 nm. Preferably, the developer is selected from one or more of the following: MIBK:IPA mixed solution, xylene:p-dioxane mixed solution, MIAK:2-pentanone mixed solution, MEK:ethanol mixed solution, TMAH:DI mixed solution, more preferably selected from one or more of the following: MIBK / IPA mixed solution, xylene / p-dioxane mixed solution, MIAK / 2-pentanone mixed solution, and even more preferably: MIBK:IPA mixed solution or xylene:p-dioxane mixed solution; preferably, the development time is 30~600s, more preferably 30~300s, and even more preferably 30~180s; and / or Preferably, the exposure time is 1~300s, more preferably 1~180s, and even more preferably 1~60s.

5. The preparation method according to any one of claims 1 to 4, characterized in that, In step (3), The etching time is 5~240s, preferably 5~120s; The etching gas is selected from one or more of the following: Ar, O2, CF4, SF6, NF3, SiCl4, preferably selected from one or more of the following: Ar, O2, CF4, SF6; The etching pressure is ≤8Pa, preferably ≤5Pa; The etching ion beam current is ≥15mA, preferably ≥20mA; and / or The ion beam voltage for etching is ≤800V, preferably ≤600V.

6. The preparation method according to any one of claims 1 to 5, characterized in that, In step (4), the film is transferred to the thin film deposition chamber through vacuum to avoid exposure to the atmosphere and causing surface adsorption or secondary oxidation at the interface; wherein, the thin film is a metal thin film; Preferably, the material of the thin film is selected from one or more of the following: aluminum, lead, niobium titanium nitride, tin; more preferably, it is selected from one or more of the following: aluminum, lead, niobium titanium nitride; and even more preferably, aluminum or lead; and / or Preferably, step (4) further includes using a cold substrate to improve the quality of the deposited film.

7. The preparation method according to any one of claims 1 to 5, characterized in that, In step (4), a transition layer is deposited to prevent direct oxidation of the interface, and then the material is transferred to a thin film deposition device for thin film deposition; wherein, the thin film is a metal thin film. Preferably, the material of the thin film is selected from one or more of the following: aluminum, lead, niobium titanium nitride, tin; more preferably, it is selected from one or more of the following: aluminum, lead, niobium titanium nitride; and even more preferably, aluminum or lead; and / or Preferably, step (4) further includes using a cold substrate to improve the quality of the deposited film.

8. The preparation method according to any one of claims 1 to 7, characterized in that, In step (5), the sample after the film deposition is placed in the adhesive removal solution to peel off the excess film, thereby obtaining the semiconductor composite device. Preferably, the adhesive remover solution is selected from one or more of the following: acetone, methyl isobutyl ketone, butyl acetate, dimethylformamide, dichloromethane, propylene glycol monomethyl ether acetate, trichloroethylene, N-methylpyrrolidone, methyl ethyl ketone; more preferably selected from one or more of the following: acetone, methyl isopropanone, butyl acetate, dimethylformamide, propylene glycol monomethyl ether acetate, trichloroethylene; and even more preferably selected from one or more of the following: acetone, methyl isopropanone, butyl acetate, dimethylformamide, propylene glycol monomethyl ether acetate; and / or Preferably, the auxiliary method for removing adhesive is selected from one or more of the following: dropper blowing, air gun blowing, ultrasonic vibration.

9. A semiconductor superconducting composite device, characterized in that, The semiconductor superconducting composite device is prepared according to the preparation method of any one of claims 1 to 8.

Images