Nanometer vacuum channel diode, preparation method thereof and electronic component

Abstract

The application discloses a nano vacuum channel diode and a preparation method thereof and an electronic component, and particularly relates to the technical field of micro-nano vacuum electronic devices. The preparation method of the nano vacuum channel diode comprises the following steps: depositing an insulating layer on an anode layer; etching the insulating layer to form a nano channel exposing part of the anode layer; depositing a sacrificial layer; etching the sacrificial layer based on a second pattern to reserve the sacrificial layer in a region corresponding to a preset cathode structure; depositing a metal film on the insulating layer and the remaining sacrificial layer to form a fixed end and a suspended end of the cathode structure, the fixed end being arranged on a side of the insulating layer away from a substrate, the suspended end extending above the nano channel, and the suspended end having a field emission tip, the field emission tip being self-formed in the process of depositing the metal film to form the suspended end; and removing the remaining sacrificial layer by etching to form a channel gap between the suspended end and the anode layer. The application improves the stability of the nano gap of the nano vacuum channel diode.

Description

Technical Field

[0001] This application relates to the field of micro-nano vacuum electronic device technology, and in particular to nano-vacuum channel diodes and their fabrication methods, as well as electronic components. Background Technology

[0002] As silicon-based CMOS (Complementary Metal-Oxide-Semiconductor) technology advances to the deep nanoscale, charge carriers in solid-state channels are limited by lattice scattering and impurity scattering. Simultaneously, short-channel effects intensify, leakage current rises sharply, and device performance degradation is particularly pronounced under extreme environments such as high temperature and high radiation. In contrast, the vacuum environment offers higher insulation strength and electron mobility, and the ballistic transport of electrons in a vacuum effectively avoids the scattering problems present in solids. However, vacuum electronic devices rely on high-vacuum sealing to maintain the long mean free path of electrons. Miniaturization results in a small internal space and a large specific surface area, making it extremely difficult to maintain a high vacuum, and the packaging cost and technological barriers are far higher than ordinary packaging. In recent years, nanoscale vacuum channel field emission devices have significantly reduced the collision probability of electrons during transport by shrinking the anode-cathode spacing to the nanoscale, thus achieving near-vacuum transport effects under ambient pressure.

[0003] However, in existing nano-vacuum channel field emission devices, the cathode structure is usually in the form of a planar or suspended thin film. During the formation of the nano gap, the suspended part of the cathode is prone to collapse or deformation due to the lack of effective mechanical support, which leads to uncontrollable changes in the nano-level gap size between the anode and cathode, and may even cause a short circuit due to direct contact between the anode and cathode. Summary of the Invention

[0004] The main objective of this application is to provide a nano-vacuum channel diode and its fabrication method, as well as an electronic component, in order to solve the technical problem that the cathode suspension structure in existing nano-vacuum field emission devices is prone to collapse or deformation, which leads to instability of the nanoscale gap between the cathode and anode, and thus affects the stability of the diode.

[0005] To achieve the above objectives, embodiments of this application provide a method for fabricating a nano-vacuum channel diode, the method comprising: An anode layer is formed on one side of the substrate; An insulating layer is deposited on the side of the anode layer opposite to the substrate; The insulating layer is etched according to a preset first pattern to form a nanochannel that exposes a portion of the anode layer; A sacrificial layer is deposited on the side of the insulating layer and the nanochannel facing away from the substrate; A preset second pattern is defined on the surface of the sacrificial layer, and the sacrificial layer is etched based on the second pattern, retaining the sacrificial layer in the region corresponding to the preset cathode structure; A metal thin film is deposited on the side of the insulating layer and the remaining sacrificial layer away from the substrate to form a fixed end and a suspended end of the cathode structure. The fixed end is disposed on the side of the insulating layer away from the substrate, and the suspended end extends above the nanochannel. The suspended end has a field emission tip, which is self-formed during the deposition of the metal thin film to form the suspended end. By etching away the remaining sacrificial layer, a channel gap is formed between the suspended end and the anode layer, resulting in a nano-vacuum channel diode.

[0006] In one embodiment, the ratio between the thickness of the sacrificial layer and the width of the channel gap is ≥ (1:2).

[0007] In one embodiment, the width of the nanochannel is ≥3 nm; And / or, the thickness of the sacrificial layer is ≥1.5 nm.

[0008] In one embodiment, the insulating layer comprises silicon dioxide and / or aluminum oxide; And / or, the sacrificial layer comprises silicon nitride and / or zinc oxide.

[0009] In one embodiment, the metal thin film includes an adhesion layer and a conductive layer, and the step of depositing the metal thin film on the side of the insulating layer and the remaining sacrificial layer opposite to the substrate to form the fixed end and the suspended end of the cathode structure includes: A third pattern of the cathode structure is defined on the surfaces of the insulating layer and the remaining sacrificial layer, the third pattern including the region of the fixed end and the region of the suspended end; An adhesion layer is deposited on the side of the insulating layer and the sacrificial layer opposite to the substrate according to the third pattern; A conductive layer is deposited on the side of the adhesion layer opposite to the insulating layer and the sacrificial layer; The adhesive layer and the conductive layer, excluding the third pattern, are peeled off to form the cathode structure of the cantilever beam.

[0010] In one embodiment, the remaining sacrificial layer is removed by selective etching, wherein the selective etching ratio of the sacrificial layer to the insulating layer is ≥ (100:1).

[0011] This application embodiment also provides a nano-vacuum channel diode prepared by the above-described method, wherein the nano-vacuum channel diode comprises: Substrate; An anode layer is disposed on one side of the substrate; An insulating layer is disposed on the side of the anode layer opposite to the substrate, and nanochannels are formed in the insulating layer to expose a portion of the anode layer; A cathode structure, wherein the cathode structure is a cantilever beam structure, the cantilever beam structure includes a fixed end and a suspended end, the suspended end having a field emission tip, the field emission tip being self-formed during the process of metal thin film deposition to obtain the suspended end; The fixed end is disposed on the side of the insulating layer away from the substrate, and the suspended end extends above the nanochannel to form a channel gap, wherein the channel gap is formed by removing the sacrificial layer located between the nanochannel and the suspended end.

[0012] In one embodiment, the cathode structure includes an adhesive layer and a conductive layer, wherein the adhesive layer is disposed on the side of the conductive layer close to the insulating layer, and the conductive layer is disposed on the side of the adhesive layer away from the insulating layer.

[0013] In one embodiment, the cantilever beam structure includes at least one of a cross shape, a straight line shape, and a star shape.

[0014] This application also provides an electronic component comprising a nano-vacuum channel diode as described above, or a nano-vacuum channel diode prepared by the method described above.

[0015] One or more technical solutions proposed in this application have at least the following technical effects: The fabrication method of a nano-vacuum channel diode includes: forming an anode layer on one side of a substrate; depositing an insulating layer on the side of the anode layer away from the substrate; constructing a basic structure for bottom conductivity and electrical isolation for the diode. The insulating layer is etched according to a preset first pattern to form a nano-channel exposing a portion of the anode layer; a physical channel is reserved for the transport of electrons from the cathode to the anode. A sacrificial layer is deposited on the side of the insulating layer and the nano-channel away from the substrate; a preset second pattern is defined on the surface of the sacrificial layer; the sacrificial layer is etched based on the second pattern, retaining the sacrificial layer in the region corresponding to the preset cathode structure; a metal thin film is deposited on the side of the insulating layer and the remaining sacrificial layer away from the substrate to form a fixed end and a suspended end of the cathode structure. The fixed end is located on the side of the insulating layer away from the substrate, and the suspended end extends above the nano-channel, and the suspended end has a field emission tip, which is self-formed during the deposition of the metal thin film to form the suspended end; the remaining sacrificial layer is removed by etching, forming a channel gap between the suspended end and the anode layer, thus obtaining a nano-vacuum channel diode. By employing a cantilever beam cathode structure design, the fixed end is positioned on the side of the insulating layer away from the substrate to provide a robust mechanical anchor. The suspended end extends above the nanochannel, creating a channel gap between the suspended portion of the cathode and the underlying anode layer. This channel gap is formed by removing the sacrificial layer located between the nanochannel and the suspended end. Due to the cantilever beam structure's characteristic of being fixed at one end and suspended at the other, it maintains a stable spatial shape after the sacrificial layer is removed, relying on the anchoring effect of the fixed end. This avoids the collapse problem of the suspended portion caused by the lack of effective mechanical support in traditional planar structures. Furthermore, the cantilever beam structure exhibits a certain degree of mechanical flexibility, which can alleviate residual stress generated during the metal thin film deposition process to some extent, thereby preventing film cracking or interface peeling caused by stress concentration. This further improves the structural stability of the device under long-term operating conditions. The field emission tip at the suspended end is formed automatically during the deposition process, eliminating the need for independent tip patterning or etching. This avoids interface defects and stress concentration introduced by subsequent processing, further ensuring the stability of the cantilever beam's shape after release. Therefore, this application improves the stability of the nano-gap in nano-vacuum channel diodes. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart illustrating the fabrication method of the nano-vacuum channel diode involved in the embodiments of this application. Figure 1 ; Figure 2 This is a schematic flowchart illustrating the fabrication method of the nano-vacuum channel diode involved in the embodiments of this application. Figure 2 ; Figure 3 This is a schematic diagram of the structure of the nano-vacuum channel diode involved in the embodiments of this application. Figure 1; Figure 4 This is a schematic diagram of the structure of the nano-vacuum channel diode involved in the embodiments of this application. Figure 2 ; Figure 5 This is a schematic diagram of the driving voltage-emission current current characteristic curve of the nano-vacuum channel diode involved in the embodiments of this application.

[0017] Explanation of reference numerals in the attached figures: 10. Substrate; 20. Anode layer; 210. First adhesion layer; 220. First conductive layer; 30. Insulating layer; 310. Second adhesion layer; 320. Nanochannel; 330. Channel gap; 40. Cathode structure; 41. Fixed end; 42. Suspended end; 421. Field launch tip; 50. Sacrificial layer. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0019] The following detailed description, with appropriate reference to the accompanying drawings, discloses the nano-vacuum channel diode and its fabrication method, as well as embodiments of the electronic device. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0020] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0021] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0022] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0023] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if a method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if a method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0024] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0025] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0026] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the technical solution of this application is further described below in conjunction with the accompanying drawings and embodiments. However, this application is not limited to the listed embodiments, but should also include any other well-known modifications within the scope of the claims made in this application.

[0027] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of this application. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0028] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0029] In existing nano-vacuum channel field emission devices, the cathode structure typically takes the form of a planar or suspended thin film. During the formation of the nano-gap, the suspended portion of the cathode is prone to collapse or deformation due to the lack of effective mechanical support, leading to uncontrollable changes in the nanoscale gap size between the anode and cathode, and even causing a short circuit due to direct contact between the anode and cathode. Furthermore, in existing field emission devices, the cathode tip usually needs to be precisely fabricated using electron beam lithography or other high-resolution nanofabrication techniques. This not only increases the complexity of the process but also makes it difficult to maintain a consistent tip morphology during large-scale manufacturing.

[0030] This application provides a solution for fabricating a nano-vacuum channel diode, comprising: forming an anode layer on one side of a substrate; depositing an insulating layer on the side of the anode layer away from the substrate; thus constructing a basic structure for bottom conductivity and electrical isolation of the diode. The insulating layer is etched according to a predetermined first pattern to form a nanochannel exposing a portion of the anode layer, reserving a physical channel for electron transport from the cathode to the anode. A sacrificial layer is deposited on the insulating layer and the nanochannel on the side away from the substrate; a predetermined second pattern is defined on the surface of the sacrificial layer, and the sacrificial layer is etched based on the second pattern, retaining the sacrificial layer in the region corresponding to the predetermined cathode structure; a metal thin film is deposited on the insulating layer and the remaining sacrificial layer on the side away from the substrate to form a fixed end and a suspended end of the cathode structure, wherein the fixed end is disposed on the side of the insulating layer away from the substrate, and the suspended end extends above the nanochannel and has a field emission tip, which is self-formed during the deposition of the metal thin film to form the suspended end; the remaining sacrificial layer is removed by etching, forming a channel gap between the suspended end and the anode layer, thus obtaining a nano-vacuum channel diode. By employing a cantilever beam cathode structure design, the cathode structure includes a fixed end and a suspended end. The fixed end is located on the side of the insulating layer facing away from the substrate to provide a strong mechanical anchor. The suspended end extends above the nanochannel, forming a channel gap between the suspended portion of the cathode and the underlying anode layer. This channel gap is created by removing the sacrificial layer located between the nanochannel and the suspended end. Due to the cantilever beam structure's characteristic of being fixed at one end and suspended at the other, it can maintain a stable spatial shape after the sacrificial layer is removed, relying on the anchoring effect of the fixed end. This avoids the problem of traditional planar structures lacking stability. The cantilever beam structure effectively mitigates the collapse of suspended sections due to mechanical support, and its mechanical flexibility alleviates residual stress generated during metal thin film deposition, thus preventing film cracking or interface peeling caused by stress concentration. This further improves the structural stability of the device under long-term operating conditions. The field emission tip at the suspended end is self-formed during the deposition process, eliminating the need for independent tip patterning or etching. This avoids interface defects and stress concentration introduced by subsequent processing, further ensuring the stability of the cantilever beam's shape after release. Therefore, this application improves the stability of the nano-gap in nano-vacuum channel diodes. Furthermore, this application's embodiments introduce a self-forming mechanism based on metal thin film deposition, allowing the cathode tip to form naturally during deposition, thereby avoiding reliance on high-precision photolithography and significantly reducing manufacturing difficulty.

[0031] The first aspect of this application provides a method for fabricating a nano-vacuum channel diode, referring to... Figure 1 and Figure 2 The methods include: Step S10: An anode layer 20 is formed on one side of the substrate 10; In one embodiment, an anode layer is formed on a substrate to provide a conductive substrate and an electron collecting electrode for subsequent device fabrication.

[0032] Optionally, a first adhesion layer 210 and a first conductive layer 220 are sequentially deposited on the substrate to form a composite anode layer 20; wherein the first adhesion layer may be Ti and the first conductive layer may be Au. Ti has good adhesion to the silicon substrate, and Au also has excellent adhesion to Ti. The Ti layer can also act as a diffusion barrier layer to prevent Au from diffusing into the silicon substrate during subsequent heat treatment.

[0033] Alternatively, the anode layer can be deposited by electron beam evaporation, magnetron sputtering, thermal evaporation or atomic layer deposition.

[0034] Step S20: Deposit an insulating layer 30 on the side of the anode layer 20 away from the substrate 10; In one embodiment, an insulating layer is deposited on the anode layer to achieve electrical isolation between the anode and cathode structures and prevent electrical short circuits between the anode and cathode.

[0035] In one feasible implementation, the insulating layer comprises silicon dioxide and / or aluminum oxide.

[0036] When silicon dioxide (SiO2) is used as an insulating layer, it provides reliable electrical isolation between the anode layer and the cathode structure to prevent electrical short circuits. Its precisely controlled deposition thickness defines the depth of the nanochannels, which in turn determines the vertical distance between the cathode suspension end and the anode. At the same time, SiO2 and the sacrificial layer have an extremely high etching selectivity during thermal etching, so it can effectively act as an etching stop layer during the release of the sacrificial layer, protecting the underlying anode layer and the main structure of the device from damage.

[0037] When aluminum oxide (Al2O3) is used as an insulating layer, it has a higher dielectric constant (about 7~9, about twice that of SiO2), which can provide stronger insulation and higher equivalent breakdown voltage at the same physical thickness. At the same time, the deposited aluminum oxide film has extremely high density and excellent step coverage, which can form a uniform and pinhole-free insulating layer on the sidewall of nanochannels. Furthermore, Al2O3 has good etching selectivity when combined with a variety of sacrificial layer materials, making it suitable for applications requiring higher insulation strength, more precise thickness control, or special sacrificial layer device structures.

[0038] Optionally, a second adhesion layer 310 and an insulating layer 30 are sequentially deposited on the anode layer. The second adhesion layer can increase the bonding strength between the insulating layer and the anode layer, thereby increasing the stability of the diode structure.

[0039] Optionally, the second adhesive layer may be a Cr layer.

[0040] Alternatively, the insulating layer is deposited by PECVD (Plasma Enhanced Chemical Vapor Deposition), during which deposition parameters are controlled to obtain a dense and uniform insulating layer.

[0041] Step S30: Etch the insulating layer 30 according to the preset first pattern to form a nanochannel 320 that exposes a portion of the anode layer 20; In one embodiment, the insulating layer is etched according to a first pattern to form a nanochannel with a nanoscale opening penetrating the insulating layer and exposing the surface of the underlying anode layer. The nanochannel is a physical channel for electrons to be transported from the cathode structure to the anode layer.

[0042] Optionally, the first pattern refers to a preset pattern used to etch the insulating layer to form nanochannels, i.e., the planar shape and positional layout of the nanochannels on the surface of the insulating layer.

[0043] Optionally, the etching method for the insulating layer includes ICP (Inductively Coupled Plasma) etching, in which an electron beam photoresist is coated on the surface of the silicon dioxide insulating layer, and a first pattern is defined by electron beam exposure. Then, the silicon dioxide is anisotropically etched using the ICP etching process to form a nanochannel structure that penetrates the insulating layer and exposes a portion of the underlying anode region.

[0044] Step S40: Deposit a sacrificial layer 50 on the side of the insulating layer 30 and the nanochannel 320 facing away from the substrate 10; In one embodiment, a sacrificial layer is deposited on the surface of the insulating layer on which the nanochannel has been formed. The sacrificial layer simultaneously covers the flat area of ​​the insulating layer and the sidewalls and bottom of the nanochannel, forming a temporary support layer that covers the entire surface.

[0045] Optionally, the sacrificial layer can be deposited using ALD (Atomic Layer Deposition). During the deposition process, the accuracy of the sacrificial layer thickness is ensured by controlling the deposition parameters.

[0046] In one feasible implementation, the sacrificial layer comprises silicon nitride and / or zinc oxide.

[0047] Silicon nitride is widely used in semiconductor processes. Its deposition and thermal phosphoric acid etching processes are mature and have a high etching selectivity for silicon dioxide. This can reduce damage to the insulating layer and channel sidewalls during sacrificial layer release, ensuring the integrity of the cantilever beam structure.

[0048] Zinc oxide, as an alternative material, can be wet-etched using dilute hydrochloric acid or ammonium chloride solution, with minimal chemical impact on the surrounding structure, making it suitable for process scenarios requiring mild etching conditions.

[0049] Step S50: Define a preset second pattern on the surface of the sacrificial layer 50, etch the sacrificial layer 50 based on the second pattern, and retain the sacrificial layer 50 in the region corresponding to the preset cathode structure 40. In one embodiment, the sacrificial layer covering the entire surface is locally patterned using photolithography and etching processes. The sacrificial layer is retained where it is needed to support the cathode structure, and removed in the remaining areas. This delineates the boundaries between the fixed end and the suspended end of the cantilever beam cathode structure in three-dimensional space.

[0050] Optionally, the second pattern refers to a preset mask pattern used to etch the sacrificial layer to form the support pattern of the cantilever beam structure.

[0051] The pre-defined cathode structure area refers to the area used to support the cathode structure.

[0052] In step S60, a metal thin film is deposited on the side of the insulating layer 30 and the remaining sacrificial layer 50 away from the substrate 10 to form a fixed end and a suspended end of the cathode structure. The fixed end is disposed on the side of the insulating layer away from the substrate, and the suspended end extends above the nanochannel. The suspended end has a field emission tip, which is formed by itself during the deposition of the metal thin film to form the suspended end. In one embodiment, a cathode structure is defined on the patterned sacrificial layer by electron beam lithography, and a cantilever beam cathode structure is formed by metal deposition and lift-off processes.

[0053] Optionally, the self-formation of the field emission tip refers to the natural growth of a sharp protrusion with an extremely small radius of curvature at the leading edge of the suspended end during the metal thin film deposition process due to the edge effect and morphological evolution of the film, without the need for additional photolithography or etching steps. After reaching the substrate surface, deposited atoms tend to nucleate and aggregate at the lower-energy edge positions (edge ​​aggregation effect); the already grown edge protrusions block subsequent incident atoms (shadowing effect), causing more atoms to be deposited at the tip of the protrusion; at low temperatures, the migration distance of atoms on the surface is limited, making it difficult for them to diffuse from the edge region to the flat region (surface diffusion limitation). The combined effect of these three factors results in the natural formation of a sharp protrusion at the edge.

[0054] Optionally, electron beam photoresist is first coated on the patterned sacrificial layer and insulating layer surface. The planar pattern of the cathode structure (including the fixed end region and the suspended end region) is defined by electron beam exposure. After development, the window region where the metal thin film needs to be deposited is exposed. Then, the adhesion layer and conductive layer are deposited sequentially with the photoresist. At this time, the metal thin film covers both the substrate surface within the window region and the photoresist surface outside the window. Finally, the photoresist is dissolved with an organic solvent, and the metal on the photoresist is stripped away. Only the metal thin film within the window region remains on the substrate, forming a cantilever beam cathode structure.

[0055] In one feasible embodiment, step S60, where the metal thin film includes an adhesion layer and a conductive layer, involves depositing a metal thin film on the side of the insulating layer and the remaining sacrificial layer facing away from the substrate to form the fixed end and the suspended end of the cathode structure. Step S610: Define a third pattern of the cathode structure on the surfaces of the insulating layer and the remaining sacrificial layer, wherein the third pattern includes a region of fixed end and a region of suspended end; In one embodiment, a third pattern of the cathode structure is defined by electron beam lithography on the patterned surfaces of the sacrificial layer and the insulating layer. The third pattern includes the planar shape and positional layout of the fixed end region and the suspended end region of the cantilever cathode, providing a patterned template for subsequent metal thin film deposition and lift-off processes.

[0056] Optionally, electron beam photoresist is coated on the surfaces of the sacrificial layer and insulating layer after patterning according to the third pattern. An electron beam is used to expose the photoresist according to the preset pattern, and the photoresist in the exposed area is removed to expose the window area where a metal thin film needs to be deposited.

[0057] Step S620: Deposit an adhesion layer on the side of the insulating layer and sacrificial layer away from the substrate according to the third pattern; In one embodiment, metal is deposited as an adhesion layer in the window area exposed by photoresist development, providing an adhesion substrate for the subsequent deposition of conductive layers.

[0058] Step S630: Deposit a conductive layer on the side of the adhesion layer away from the insulating layer and the sacrificial layer; Step S640: Peel off the adhesive layer and conductive layer outside the third pattern to form the cathode structure of the cantilever beam.

[0059] In one embodiment, a conductive layer is deposited on the entire substrate (covering the window area and the photoresist surface), and the metal film on the photoresist is finally removed by a stripping process, leaving only the composite cathode structure in the window area.

[0060] In this embodiment, by integrally forming the fixed end and the suspended end of the cathode structure in the same deposition step, interface defects and stress concentrations introduced by subsequent processing are avoided, ensuring the structural stability of the cantilever beam after release. The adhesion layer enhances the bonding force between the conductive layer and the underlying material. The conductive layer serves as the main conductive and emitting layer, and together the two constitute a composite cathode structure with stable adhesion and excellent conductivity. Electron beam lithography is used to define the pattern and combine it with the lift-off process, eliminating the need to etch the metal layer and avoiding damage to the underlying sacrificial layer and insulating layer, thus balancing pattern accuracy and the integrity of the underlying structure.

[0061] In step S70, the remaining sacrificial layer 50 is removed by etching, and a channel gap 330 is formed between the suspended end 42 and the anode layer 20 to obtain a nano-vacuum channel diode.

[0062] In one embodiment, the remaining sacrificial layer is selectively etched away to release the cathode cantilever beam structure from below, while a nanoscale channel gap is formed between the suspended end and the anode layer, thus completing the construction of the final device structure.

[0063] Optionally, after release, the sacrificial layer is completely removed, and the anchoring is achieved through direct contact between the fixed end and the insulating layer; a channel gap is formed between the suspended end and the anode layer.

[0064] In one feasible implementation, the remaining sacrificial layer is removed by selective etching, wherein the etching selectivity ratio of the sacrificial layer to the insulating layer during the selective etching process is ≥ (100:1).

[0065] In one embodiment, the remaining sacrificial layer is selectively removed by wet etching. When using an etchant to remove the sacrificial layer, a high selectivity ensures that the sacrificial layer is removed quickly while the insulating layer is hardly etched, thus avoiding damage to the nanochannel sidewalls or thinning of the insulating layer due to etching. If the selectivity is too low, the insulating layer will inevitably be corroded during the removal of the sacrificial layer, leading to channel gap size deviation, decreased insulation performance, or even leakage or short circuit between the anode and cathode, seriously affecting device yield and long-term reliability. Therefore, limiting the etching selectivity to the above range ensures both complete removal of the sacrificial layer and effective protection of the structural integrity of the insulating layer and channel sidewalls, thereby ensuring the accuracy of the channel gap size and the electrical performance of the device.

[0066] In one embodiment, when the sacrificial layer is silicon nitride (Si3N4), the etching solution is a hot phosphoric acid solution. Hot phosphoric acid has a high etching rate for silicon nitride and extremely high etching selectivity with silicon dioxide, enabling rapid removal of the sacrificial layer and effectively protecting the insulating layer and channel sidewalls from damage.

[0067] In one embodiment, when the sacrificial layer is zinc oxide (ZnO), the etching solution is a dilute hydrochloric acid solution. Dilute hydrochloric acid has good etching selectivity for zinc oxide and causes less chemical damage to surrounding structural materials such as silicon dioxide, making it suitable for process scenarios that require mild etching conditions.

[0068] In this embodiment, through the coordinated design of multiple technical elements such as cantilever beam structure, self-forming tip, film thickness definition dimension, and sacrificial layer release, the fixed end and the suspended end of the cathode structure are integrally formed. The fixed end is supported by the sacrificial layer, and the suspended end spans above the nanochannel. Combined with the self-forming tip naturally generated during the deposition process, it avoids interface defects and stress concentration introduced by subsequent processing, ensuring the structural stability after the cantilever beam is released. At the same time, the channel gap size is precisely controlled by the film deposition thickness, making the gap smaller than the mean free path of electrons under atmospheric pressure, realizing near-vacuum transport under normal pressure, and reducing packaging requirements. The composite cathode structure of the adhesion layer and conductive layer enhances adhesion and conductivity. Electron beam lithography and lift-off process avoid etching damage to the underlying sacrificial layer and insulating layer, balancing pattern accuracy and the integrity of the underlying structure. The high etching ratio between the sacrificial layer and the insulating layer ensures that the sacrificial layer is completely removed while protecting the insulating layer and channel sidewalls from damage. Thus, while reducing manufacturing difficulty, improving dimensional consistency and structural stability, a nano-vacuum channel diode that can operate at normal pressure and has long-term reliability is obtained.

[0069] In one feasible implementation, the ratio between the thickness of the sacrificial layer and the width of the channel gap is ≥ (1:2).

[0070] In one embodiment, the thickness of the sacrificial layer determines the vertical height of the channel gap, and the width of the channel gap determines the horizontal range of the gap. Together, they define the geometry of the transport space through which electrons travel from the field emission tip across the channel gap to the anode. The ratio of the sacrificial layer thickness to the channel gap width is greater than or equal to 1:2. By limiting the ratio of the sacrificial layer thickness to the channel gap width to this ratio, it is possible to ensure that the channel gap has sufficient height in the vertical direction to maintain an effective electric field acceleration region, allowing electrons to gain sufficient kinetic energy during the passage of the channel gap. At the same time, it avoids the loss of energy or deviation from the trajectory due to collisions with the channel sidewalls before reaching the anode caused by a channel gap that is too shallow. Furthermore, the above ratio helps to form a uniform and stable electric field distribution inside the channel gap, avoiding distortion or non-uniformity of the electric field in the effective action area between the field emission tip and the anode layer due to a ratio that is too small, thereby ensuring the stability of the emission current and the collection efficiency. In addition, the above ratio is also related to the structural strength of the device. An appropriate depth-to-width ratio can ensure that the cantilever beam structure has sufficient mechanical stability after the sacrificial layer is removed, avoiding the risk of collapse due to an excessively wide channel gap leading to an excessively large span at the suspended end, and also preventing the current output from being affected by insufficient electron transmission space due to a gap that is too narrow.

[0071] In one feasible implementation, the thickness of the sacrificial layer is ≥1.5 nm.

[0072] In one embodiment, the sacrificial layer serves as a temporary support layer, and its thickness directly determines the vertical height of the channel gap formed after it is subsequently removed. Therefore, the thickness should at least reach the minimum size required to form an effective electron transport channel. Otherwise, if the gap is too small, electrons will not be able to pass through smoothly or a breakdown risk will occur. At the same time, the thickness must also ensure that the cantilever beam structure has sufficient mechanical support strength during the deposition process to avoid breakage or deformation in subsequent processes due to the sacrificial layer being too thin.

[0073] Optionally, the thickness of the sacrificial layer can be 1.5 nm, 2 nm, 4 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, etc.

[0074] Different thicknesses of the sacrificial layer correspond to different channel gap heights, which can be determined according to different operating voltages, atmospheric pressure transport requirements, and structural strength requirements.

[0075] Optionally, the height of the trench gap is determined based on the thickness of the sacrificial layer.

[0076] In one feasible implementation, the width of the nanochannel is ≥3 nm.

[0077] In one embodiment, the width of the nanochannel can be selected according to actual process requirements and device performance requirements. Its width determines the horizontal range of the channel gap, that is, the lateral space range between the cathode suspension end and the channel sidewall. It also affects the lateral constraint of the transmission path of electrons from the tip through the gap to the anode. Therefore, the width should be at least the minimum size that can accommodate the field emission tip and ensure that electrons are not scattered or collided with the sidewall in the horizontal direction. Otherwise, if the width is too small, the tip will not be able to be correctly positioned in the center of the channel or the electrons will collide with the sidewall and lose energy. At the same time, the width also needs to match the gap height determined by the thickness of the sacrificial layer to form a suitable aspect ratio, thereby establishing a uniform and stable electric field distribution inside the gap and avoiding electric field distortion or unstable emission current due to an excessively large or small aspect ratio.

[0078] Optionally, the width of the nanochannel can be 3 nm, 5 nm, 8 nm, 10 nm, 12 nm, 15 nm, 18 nm, 20 nm, 22 nm, 25 nm, 28 nm, 30 nm, 32 nm, 35 nm, 38 nm, 40 nm, 42 nm, 44 nm, 45 nm, 48 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 120 nm, 150 nm, 200 nm, etc. Different widths of the nanochannel correspond to different gap horizontal ranges, and together with the gap vertical height determined by the sacrificial layer thickness, they constitute the aspect ratio of the channel gap, which can be determined according to different operating voltages, atmospheric pressure transport requirements, and structural strength requirements.

[0079] A second aspect of this application provides a nano-vacuum channel diode prepared by the above-described preparation method, with reference to... Figure 3 and Figure 4 Nano-vacuum channel diodes include: Substrate 10; In one embodiment, the substrate refers to a base material that provides mechanical support for the other layer materials.

[0080] Alternatively, the substrate may be a high-resistivity N-type silicon wafer.

[0081] An anode layer 20 is disposed on one side of the substrate 10; In one embodiment, the anode layer is used to collect electrons emitted from the cathode structure to form an external circuit current, providing a stable potential reference for the diode. The anode layer is disposed on one side of the substrate, providing a structural basis for the subsequent insulating layer and cathode structure.

[0082] In one embodiment, the anode layer material can be any one of Au, Pt, Pd, Ag, Cu, Al, W, doped polycrystalline silicon, amorphous silicon, SiGe alloy, and SiC.

[0083] An insulating layer 30 is disposed on the side of the anode layer 20 away from the substrate 10, and a nanochannel 320 is formed in the insulating layer 30 to expose a portion of the anode layer; In one embodiment, an insulating layer is used to achieve electrical isolation between the anode layer and the cathode structure, and is disposed on the side of the anode layer away from the substrate. A nanochannel is formed in the insulating layer, which exposes part of the structure of the anode layer, so that electrons emitted by the cathode structure can pass through the channel to reach the anode.

[0084] The cathode structure 40 is a cantilever beam structure, which includes a fixed end 41 and a suspended end 42. The suspended end has a field emission tip 421, which is formed during the process of metal thin film deposition to obtain the suspended end 42. The fixed end 41 is disposed on the side of the insulating layer 30 away from the substrate 10, and the suspended end 42 extends above the nanochannel 320 to form a channel gap 330, wherein the channel gap 330 is formed by removing the sacrificial layer located between the nanochannel 320 and the suspended end 42.

[0085] In one embodiment, the cathode adopts a cantilever beam structure, consisting of a fixed end and a suspended end; the leading edge of the suspended end has a field emission tip, which is naturally formed during the deposition of the cathode metal thin film.

[0086] One end of the cantilever beam structure is a fixed end, located on the side of the insulating layer away from the substrate, to provide mechanical support and ensure the stability of the suspended end; the other end is a suspended end, extending above the channel, to position the field emission tip of the cathode structure above the anode layer, forming a vertical electron transport path.

[0087] The leading edge of the suspended end refers to the edge closest to the center of the channel. The tip is a sharp protrusion with a small radius of curvature, which can generate a local electric field enhancement effect, which is beneficial to electron emission.

[0088] Optionally, the tip is located at the center of the leading edge of the suspended end and directly above the nanochannel.

[0089] The channel gap refers to a vertical, nanoscale space between the lower surface of the suspended end and the upper surface of the anode layer. The channel gap is not directly defined by photolithography or etched, but rather is the cavity left after removing the sacrificial layer that was originally located between the insulating layer and the suspended end.

[0090] In one feasible implementation, the cantilever beam structure includes at least one of the following: cross-shaped, straight, and star-shaped.

[0091] In one embodiment, the cross shape refers to the cantilever beam's planar projection in the top view direction (i.e., the direction perpendicular to the substrate surface) being cross-shaped. The cross-shaped cantilever beam structure includes a longitudinal arm and a transverse arm. The longitudinal arm extends from the fixed end to the portion above the nanochannel along the cantilever direction, forming the main beam where the cathode tip is located. The transverse arm extends laterally near the fixed end to increase the anchoring area.

[0092] In one embodiment, the "one-line" refers to the cantilever beam having a long strip shape (one-line) when projected in the top direction (i.e., the direction perpendicular to the substrate surface). Its main structure is a longitudinal beam extending from the fixed end to above the nanochannel along the cantilever direction. The width is basically the same or gradually narrows in the extension direction. It has the simplest structure and is suitable for scenarios with short cantilever distances and relatively simple mechanical requirements.

[0093] In one embodiment, the "X" shape refers to the cantilever beam's planar projection in the top view direction resembling an X. That is, based on the cross-shaped structure, an oblique arm is further added between the longitudinal arm and the transverse arm, which strengthens the anchoring area near the fixed end in multiple directions. This can more effectively disperse the multi-directional stress generated by the cantilever beam during release and operation, and is suitable for scenarios with large cantilever lengths or higher requirements for structural stability.

[0094] Optionally, the shape of the cantilever beam structure affects the support stability of the cathode structure. Different shape designs determine the cantilever beam's ability to resist collapse and deformation after release. At the same time, the release effect of the sacrificial layer is also closely related to the cathode shape. The cathode tip located at the center is wrapped by the sacrificial layer during processing. The size of the space released after the sacrificial layer is removed directly affects the release speed and cleanliness. The larger the space, the easier it is for the etching solution or etching gas to enter and complete the release quickly. However, an excessively large space may weaken the mechanical strength of the cantilever beam. Therefore, a trade-off must be made between the cathode shape and the sacrificial layer release effect in device design to balance structural stability and process reliability.

[0095] In one feasible embodiment, the cathode structure includes an adhesive layer and a conductive layer, wherein the adhesive layer is disposed on the side of the conductive layer close to the insulating layer, and the conductive layer is disposed on the side of the adhesive layer away from the insulating layer.

[0096] The adhesion layer is located below the conductive layer, i.e., on the side closest to the insulating layer. It enhances the adhesion between the conductive layer and the underlying insulating or sacrificial layer, preventing the conductive layer from peeling off during use. The conductive layer is located above the adhesion layer, i.e., on the side away from the insulating layer, serving as the main conductive and electron emission layer. The adhesion and conductive layers ensure that the cathode structure possesses both good adhesion stability and excellent conductivity and field emission performance.

[0097] In one embodiment, the adhesive layer may be any one of Cr, Ti, Ni, NiCr, TiW, or W.

[0098] In one embodiment, the conductive layer may be any one of Au, Pt, Pd, Ag, Ru, doped polycrystalline silicon, amorphous silicon, SiGe alloy, and SiC.

[0099] Optionally, the thickness of the adhesive layer is less than the thickness of the conductive layer.

[0100] This embodiment employs a cantilever beam cathode structure design, comprising a fixed end and a suspended end. The fixed end is positioned on the side of the insulating layer facing away from the substrate to provide a robust mechanical anchor. The suspended end extends above the nanochannel, creating a channel gap between the suspended portion of the cathode and the underlying anode layer. This channel gap is formed by removing the sacrificial layer located between the nanochannel and the suspended end. Due to the cantilever beam structure's characteristic of being fixed at one end and suspended at the other, it maintains a stable spatial shape after the sacrificial layer is removed, relying on the anchoring effect of the fixed end. This avoids the problems associated with traditional planar structures. The lack of effective mechanical support leads to the collapse of the suspended portion. Furthermore, the cantilever beam structure has a certain degree of mechanical flexibility, which can alleviate the residual stress generated during the metal thin film deposition process to a certain extent. This avoids film cracking or interface peeling caused by stress concentration, and further improves the structural stability of the device under long-term operating conditions. The field emission tip of the suspended end is formed automatically during the deposition process, without the need for independent tip patterning or etching. This avoids interface defects and stress concentration introduced by subsequent processing, and further ensures the stability of the cantilever beam after release.

[0101] A third aspect of this application provides an electronic component, including a nano-vacuum channel diode as described above, or a nano-vacuum channel diode prepared by the method described above.

[0102] In one embodiment, reference is made to Figure 5 Electronic components, including the aforementioned nano-vacuum channel diodes, can generate a high-intensity local electric field at the field emission tip of the cathode structure by applying a voltage between the cathode and anode. When the electric field intensity reaches a certain threshold, electrons escape from the cathode surface through quantum tunneling and propagate into the nanochannel. Because the channel size is at the nanoscale, electrons undergo almost no scattering during propagation, thus enabling them to quickly reach the anode and generate current output. Figure 5 The curves show the typical voltage-current variation of a field emission device. In the low-voltage range of 1V to 5V, the electric field strength at the field emission tip does not reach the electron tunneling threshold, and there is only a very weak tunneling current. The curve is close to the horizontal axis with almost no rise. In the medium-voltage range of 5V to 8V, the electric field gradually reaches the tunneling critical value, and the electron tunneling effect appears. The current increases slowly and nonlinearly with the increase of voltage. In the high-voltage range of 8V to 10V, the local electric field at the cathode is greatly enhanced, and the number of tunneled electrons increases rapidly. Electrons in the nanochannel are transported to the anode without scattering. The slope of the current curve increases significantly and rises sharply. This fully reflects the nonlinear growth of the tunneling current with the driving voltage of the nanochannel field emission device.

[0103] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the patent protection scope of this application.

Claims

1. A method for fabricating a nano-vacuum channel diode, characterized in that, The method includes: An anode layer is formed on one side of the substrate; An insulating layer is deposited on the side of the anode layer opposite to the substrate; The insulating layer is etched according to a preset first pattern to form a nanochannel that exposes a portion of the anode layer; A sacrificial layer is deposited on the side of the insulating layer and the nanochannel facing away from the substrate; A preset second pattern is defined on the surface of the sacrificial layer, and the sacrificial layer is etched based on the second pattern, retaining the sacrificial layer in the region corresponding to the preset cathode structure; A metal thin film is deposited on the side of the insulating layer and the remaining sacrificial layer away from the substrate to form a fixed end and a suspended end of the cathode structure. The fixed end is disposed on the side of the insulating layer away from the substrate, and the suspended end extends above the nanochannel. The suspended end has a field emission tip, which is self-formed during the deposition of the metal thin film to form the suspended end. By etching away the remaining sacrificial layer, a channel gap is formed between the suspended end and the anode layer, resulting in a nano-vacuum channel diode.

2. The method for fabricating a nano-vacuum channel diode as described in claim 1, characterized in that, The ratio between the thickness of the sacrificial layer and the width of the channel gap is ≥ (1:2).

3. The method for fabricating a nano-vacuum channel diode as described in claim 1, characterized in that, The width of the nanochannel is ≥3 nm; And / or, the thickness of the sacrificial layer is ≥1.5 nm.

4. The method for fabricating a nano-vacuum channel diode as described in claim 1, characterized in that, The insulating layer comprises silicon dioxide and / or aluminum oxide; And / or, the sacrificial layer comprises silicon nitride and / or zinc oxide.

5. The method for fabricating a nano-vacuum channel diode as described in claim 1, characterized in that, The metal thin film includes an adhesion layer and a conductive layer. The step of depositing the metal thin film on the side of the insulating layer and the remaining sacrificial layer opposite to the substrate to form the fixed end and the suspended end of the cathode structure includes: A third pattern of the cathode structure is defined on the surfaces of the insulating layer and the remaining sacrificial layer, the third pattern including the region of the fixed end and the region of the suspended end; An adhesion layer is deposited on the side of the insulating layer and the sacrificial layer opposite to the substrate according to the third pattern; A conductive layer is deposited on the side of the adhesion layer opposite to the insulating layer and the sacrificial layer; The adhesive layer and the conductive layer, excluding the third pattern, are peeled off to form the cathode structure of the cantilever beam.

6. The method for fabricating a nano-vacuum channel diode as described in claim 1, characterized in that, The remaining sacrificial layer is removed by selective etching, wherein the etching selectivity ratio of the sacrificial layer to the insulating layer during the selective etching process is ≥ (100:1).

7. A nano-vacuum channel diode, characterized in that, The nano-vacuum channel diode is prepared by the fabrication method of any one of claims 1 to 6, wherein the nano-vacuum channel diode comprises: Substrate; An anode layer is disposed on one side of the substrate; An insulating layer is disposed on the side of the anode layer opposite to the substrate, and nanochannels are formed in the insulating layer to expose a portion of the anode layer; A cathode structure, wherein the cathode structure is a cantilever beam structure, the cantilever beam structure includes a fixed end and a suspended end, the suspended end having a field emission tip, the field emission tip being self-formed during the process of metal thin film deposition to obtain the suspended end; The fixed end is disposed on the side of the insulating layer away from the substrate, and the suspended end extends above the nanochannel to form a channel gap, wherein the channel gap is formed by removing the sacrificial layer located between the nanochannel and the suspended end.

8. The nano-vacuum channel diode as described in claim 7, characterized in that, The cathode structure includes an adhesion layer and a conductive layer, wherein the adhesion layer is disposed on the side of the conductive layer close to the insulating layer, and the conductive layer is disposed on the side of the adhesion layer away from the insulating layer.

9. The nano-vacuum channel diode as described in claim 7, characterized in that, The cantilever beam structure includes at least one of the following: cross-shaped, straight-line, and star-shaped.

10. An electronic component, characterized in that, A nano-vacuum channel diode prepared by the method of any one of claims 1 to 6, or a nano-vacuum channel diode prepared by any one of claims 7 to 9.

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