Metal carbide film based on vacuum interconnection and preparation method thereof

Abstract

The invention discloses a metal carbide film based on vacuum interconnection and a preparation method thereof. The film at least comprises a carbide structure which is obtained by taking a transition metal crystal material with a planar interface or a metal material with a polished interface as a substrate, carrying out controllable carbonization with carbon source gas and carrying out ultrahigh vacuum annealing impurity removal. The method is simple in process, the preparation process is further optimized aiming at the problem that a certain amount of carbon deposits often exist on the surface of a carbonized material and are difficult to eradicate due to high-temperature carbonization of conventional organic gas, and the carbon deposits are completely removed in a UHV annealing mode by means of in-situ preparation and monitoring protection of near-normal-pressure XPS, so that the pure carbide film is obtained.

Description

Technical Field

[0001] The present invention relates to metal carbide film technology, in particular to a metal carbide film based on vacuum interconnection and a preparation method thereof. Background Art

[0002] Transition metal carbides are a class of materials with special properties. Their composition can be abbreviated as MCx, where x can be an integer or a fraction. As an intermetallic filling compound, C atoms are interstitially integrated into the lattice of transition metals to form this type of material.

[0003] There are two main methods for preparing transition metal carbides: hydrothermal synthesis and direct carbonization. Currently, direct carbonization is the mainstream method for preparing carbide powder samples. The carbon source used for carbonization is generally low-carbon alkanes or alkenes, such as methane, propane, ethylene, etc.; if the precursor is rich in carbon components, the corresponding carbides can also be obtained by high-temperature calcination under the protection of an inert atmosphere. Based on single crystals or flat metal substrates such as transition metal polycrystalline blocks, carbonization is carried out in a high vacuum environment or under a controllable atmosphere to obtain a series of carbide structures with flat surfaces. This type of work can be divided into two main methods. One is the traditional surface science preparation method, that is, in an ultra-high vacuum chamber, a single crystal substrate with a specific crystal plane, such as Mo (100), is subjected to argon etching annealing and other cleaning steps. On this basis, about 10 -7 Up to 10 -6 The carbonization gas source (low-carbon alkanes, olefins, etc.) of mbar level is used to carbonize at a higher annealing temperature. The surface structure of the model obtained by this method is relatively regular, but the thickness of its molybdenum carbide is often only one to several layers on the surface, which is difficult to truly simulate the bulk structure of the actual molybdenum carbide material. The second method is to place the transition metal substrate in a quartz tube, pass the carburizing gas source, and carbonize at a higher temperature. The thickness of the carbide material obtained by this method is usually bulk carbide, and the structure and thickness of the obtained carbide material are uncontrollable.

[0004] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0005] The purpose of the present invention is to provide a metal carbide film based on vacuum interconnection and a preparation method thereof. The process is simple. By targeting the problem that conventional organic gas high-temperature carbonization easily causes a certain amount of carbon deposits on the surface of the carbonized material that are difficult to eradicate, the preparation process is further optimized. With the help of in-situ preparation and monitoring protection of near-normal pressure XPS, the carbon deposits are completely removed by UHV annealing (ultra-high vacuum annealing) to obtain a pure carbide film.

[0006] To achieve the above objectives, an embodiment of the present invention provides a metal carbide film based on vacuum interconnection, which at least includes a carbide structure obtained by controllably carbonizing with a carbon source gas and removing impurities by ultra-high vacuum annealing, using a transition metal crystal material with a planar interface or a metal material with a polished interface as a substrate.

[0007] In one or more embodiments of the present invention, the transition metal crystalline material is selected from transition metal single crystal materials and transition metal polycrystalline materials.

[0008] In one or more embodiments of the present invention, the transition metal crystalline material is selected from transition metal single crystal sheets and transition metal multi-crystal sheets.

[0009] In one or more embodiments of the present invention, the raw material of the transition metal crystalline material is selected from Mo and W.

[0010] In one or more embodiments of the present invention, the carbonization temperature of the controllable carbonization is 800-1070K.

[0011] In one or more embodiments of the present invention, the carbonization time of the controllable carbonization is.

[0012] In one or more embodiments of the present invention, the vacuum degree during ultra-high vacuum annealing is 10 -9 mbar.

[0013] In one or more embodiments of the present invention, the annealing temperature during ultra-high vacuum annealing is 500K-1200K.

[0014] In one or more embodiments of the present invention, the annealing time during ultra-high vacuum annealing is 10 min-30 min.

[0015] In one or more embodiments of the present invention, a method for preparing a metal carbide film based on vacuum interconnection includes: preparing a transition metal crystal material or a metal material of a polished interface, preparing a carbon source gas, performing controllable carbonization under protective conditions (protective conditions refer to conditions for isolating impurities, such as vacuum conditions, etc.), and then performing ultra-high vacuum annealing to remove impurities.

[0016] In one or more embodiments of the present invention, the carbon source gas is selected from alkanes, alkenes or alkynes of C3 and below.

[0017] As mentioned above, the metal carbide film based on vacuum interconnection may have a carbide layer and / or a substrate layer, and may be used as a functional structure or functional material in fields such as new energy catalysts (such as water gas conversion, hydrogenation and dehydrogenation, etc.), composite materials, and sensitive materials.

[0018] Transition metal carbides have special properties and application prospects, especially Mo and W-based carbides, which have electronic properties similar to those of precious metals such as platinum and have good catalytic performance in water activation processes such as water gas change and HER. x , WC x There is usually a certain amount of carbon deposits on the surface of materials such as carbon, and the materials are easily contaminated by environmental impurities such as water and oxygen in the air after the carbonization process is completed, forming surface impurity structures, thereby affecting product performance and performance analysis, such as making it difficult to clarify the relationship between related structures and performance. The present invention can ensure that the in-situ prepared carbide materials are not exposed during the characterization process of the whole process by means of ultra-high vacuum interconnection technology, combined with near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS), X-ray photoelectron spectroscopy (XPS), scanning Auger electron spectroscopy (Scanning-AES), etc., so as not to be contaminated by water, oxygen, etc. in the air, and combined with annealing and impurity removal steps, so as to maintain its original intrinsic characteristics, obtain a clean carbide film, and characterize the multiple physical and chemical properties of the material, which is more conducive to the analysis and application of the material.

[0019] Compared with the prior art, the metal carbide film based on vacuum interconnection and the preparation method thereof according to the embodiment of the present invention have at least the following advantages: the process is simple, and the preparation process is further optimized by targeting the problem that high-temperature carbonization of conventional organic gases easily causes a certain amount of carbon deposits on the surface of the carbonized material that are difficult to eradicate, and with the help of in-situ preparation and monitoring protection of near-normal pressure XPS, UHV annealing (ultra-high vacuum annealing) is used to completely remove the carbon deposits to obtain a pure carbide film. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is an in-situ near-normal pressure XPS spectrum of the carburization process of a polished Mo metal block according to an embodiment of the present invention;

[0021] Figure 2 This is an in-situ near-normal pressure XPS spectrum of the vacuum annealing and carbon removal process of the polished Mo metal block after carburization according to an embodiment of the present invention, wherein the condition marks corresponding to each curve from top to bottom in the three figures a, b, and c correspond to each other one by one;

[0022] Figure 31. The SEM top view of the polished Mo block according to one embodiment of the present invention (a); the EBSD phase diagram (b); the crystal orientation distribution diagram calculated based on the EBSD data (c); the SEM image of the MoC / Mo material after carbonization (d), the EBSD phase diagram and the calculated crystal orientation distribution diagram (e, f). DETAILED DESCRIPTION

[0023] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0024] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0025] One implementation of the present invention is mainly realized by a set of vacuum interconnection subsystems of a vacuum interconnection test station, which mainly includes three parts: a vacuum interconnection glove box, an environmental chamber, a preparation chamber, and a NAP-XPS system. The back vacuum of the environmental chamber and the preparation chamber is better than 5×10 -9 mbar, can process samples in the gas pressure range from ultra-high vacuum to 1 atmosphere, and its sample stage can cool the sample with liquid nitrogen and heat it with laser, and can maintain the sample temperature range from 100K to 1500K. The NAP-XPS system consists of a monochromatic X-ray source, an analysis cavity, a multi-stage differential electron lens, a hemispherical electron energy analyzer and a detector, and has a matching gas path. Samples can be tested in situ by XPS in the temperature range of 100K to 1500K in an atmosphere of UHV to 20mbar.

[0026] Relying on this subsystem, we can complete the sample processing and cleaning, metal component deposition, in-situ carbonization, in-situ oxidation and other tests. The glove box is equipped with a vacuum sample injection chamber. Through the ultra-high vacuum pipeline, the sample can be directly transferred from the glove box to the environmental chamber, preparation chamber or NAP-XPS system. In addition, it can also be transferred to other characterization equipment in the nano vacuum interconnection experimental station under vacuum environment for testing, ensuring that the in-situ prepared carbide film is not disturbed by impurities such as water and oxygen in the air.

[0027] The method for preparing the carbide film involved in the patent of the present invention mainly uses transition metal single crystals, polycrystalline sheets and polished polycrystalline blocks as substrate materials, and uses low-carbon alkanes, alkenes or alkynes not greater than C3 as carbon sources for carbonization in an environment where impurities are not easily introduced, such as vacuum and protective gas. The carbonization process starts from the surface and gradually penetrates into the bulk phase. As the carbonization time increases, the depth of carbonization also increases. There may be a small amount of graphite carbon residue on the surface after carbonization, which can be completely eliminated by subsequent ultra-high vacuum annealing to obtain a clean carbide film.

[0028] Example 1

[0029] In this embodiment, a polished polycrystalline Mo metal block is taken as an example. In the vacuum chamber of a near-normal pressure X-ray photoelectron spectroscopy device, ethylene at about 1 mbar is introduced. The sample is carbonized at a temperature of 800 K for 10 min. The carbonization process can be tracked in situ by NAP-XPS to ensure that the generated surface carbon is not lost in the subsequent vacuum annealing (10 -9 mbar, annealing temperature 800K, annealing time 10min) process is completely eliminated, the process is as follows Figure 2 As shown, a uniform and flat carbide thin film material with a film thickness of 0.5 microns was obtained.

[0030] Depend on Figure 3 It can be seen that the surface flatness of the Mo block after carbonization is basically the same as that of the Mo block just after polishing, and the surface has not become rough due to carbonization. EBSD data shows that the phase after carbonization is basically all Mo 2 C, there are three main surface orientations.

[0031] Example 2

[0032] The film of this embodiment is different from that of embodiment 1 only in that ethane gas of about 1 mbar is introduced. The sample results show that a uniform and flat carbide film material with a micron size can be formed, with a film thickness of 0.6 microns, and most of the impurities such as carbon on the surface (most of the impurities refer to the surface area with impurities remaining not exceeding 0.5%, the same below) are completely eliminated.

[0033] Example 3

[0034] The difference between the film of this embodiment and that of embodiment 1 is that propylene gas of about 1 mbar is introduced. The sample results show that a uniform and flat carbide film material with a micrometer size can be formed, with a film thickness of 0.7 micrometer, and most of the impurities such as carbon on the surface are completely eliminated.

[0035] Example 4

[0036] The film of this embodiment is different from that of embodiment 1 only in that acetylene gas of about 1 mbar is introduced. The sample results show that a uniform and flat carbide film material with a micron size can be formed, with a film thickness of 0.6 microns, and the surface impurities such as carbon (partial means that the surface area with impurities remaining is not more than 1%, the same below) is completely eliminated.

[0037] Example 5

[0038] The difference between the film of this embodiment and that of embodiment 1 is that about 10 -6 mbar of ethylene gas. The sample results show that a uniform and flat carbide film material with a micron size can be formed, with a film thickness of 0.1 micron, and impurities such as carbon on the surface can be completely eliminated.

[0039] Example 6

[0040] The difference between the film of this embodiment and that of embodiment 1 is that about 10 -4 mbar of ethylene gas. The sample results show that a uniform and flat carbide film material with a micron size can be formed, with a film thickness of 0.15 microns, and impurities such as carbon on the surface can be completely eliminated.

[0041] Example 7

[0042] The difference between the film of this embodiment and that of embodiment 1 is that about 10 -2 mbar of ethylene gas. The sample results show that a uniform and flat carbide film material with a micron size can be formed, with a film thickness of 0.3 microns, and impurities such as carbon on the surface can be completely eliminated.

[0043] Example 8

[0044] The film of this embodiment is different from that of embodiment 1 only in that the temperature is maintained at 1070 K for carbonization. The sample results show that a uniform and flat carbide film material with a micron size can be formed, with a film thickness of 0.7 microns, and impurities such as carbon on the surface can be completely eliminated.

[0045] Example 9

[0046] A: The difference between the film of this embodiment and that of embodiment 1 is that the temperature during carbonization is programmed to rise from 800K to 1070K at 3K / min and then maintained for carbonization, and the carbonization time is 30 minutes in total. The sample results show that a uniform and flat carbide film material with a micron size can be formed, with a film thickness of 0.8 microns, and impurities such as carbon on the surface can be completely eliminated.

[0047] B: The film of this embodiment is different from that of embodiment 1 only in that the temperature during carbonization is maintained at 1070K for 30 minutes. The sample results show that a uniform and flat carbide film material with a micron size can be formed, with a film thickness of 1 micron, and impurities such as carbon on the surface can be completely eliminated.

[0048] Example 10

[0049] The difference between the film of this embodiment and that of embodiment 1 is that the annealing temperature during ultra-high vacuum annealing is 500K and the annealing time is 30 minutes. The sample results show that a uniform and flat carbide film material with a micron size can be formed, with a film thickness of 0.52 microns, and impurities such as carbon on the surface are basically completely eliminated.

[0050] Embodiment 11

[0051] The difference between the film of this embodiment and that of embodiment 1 is that the annealing temperature during ultra-high vacuum annealing is 1200K and the annealing time is 30 minutes. The sample results show that a uniform and flat carbide film material with a micron size can be formed, with a film thickness of 0.45 microns, and impurities such as carbon on the surface can be completely eliminated.

[0052] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A metal carbide film based on vacuum interconnection, comprising at least a transition metal crystal material with a planar interface or a metal material with a polished interface as a substrate, a carbide structure obtained by controllably carbonizing with a carbon source gas and removing impurities by ultra-high vacuum annealing.

2. The metal carbide film based on vacuum interconnection according to claim 1, It is characterized in that The transition metal crystal material is selected from transition metal single crystal material and transition metal polycrystalline material.

3. The metal carbide film based on vacuum interconnection as claimed in claim 2, It is characterized in that The transition metal crystal material is selected from transition metal single crystal sheets and transition metal multi-crystal sheets.

4. The metal carbide film based on vacuum interconnection according to any one of claims 1 to 3, It is characterized in that The raw material of the transition metal crystal material is selected from Mo and W.

5. The metal carbide film based on vacuum interconnection according to claim 1, It is characterized in that The carbonization temperature of the controllable carbonization is 800-1070K.

6. The metal carbide film based on vacuum interconnection according to claim 5, It is characterized in that The carbonization time of the controllable carbonization is 10 min-30 min.

7. The metal carbide film based on vacuum interconnection according to claim 1, It is characterized in that The vacuum degree during the ultra-high vacuum annealing is 10 -9 mbar.

8. The metal carbide film based on vacuum interconnection according to claim 7, It is characterized in that The annealing temperature during the ultra-high vacuum annealing is 500K-1200K.

9. The metal carbide film based on vacuum interconnection according to claim 8, It is characterized in that The annealing time during the ultra-high vacuum annealing is 10 min-30 min.

10. The method for preparing a metal carbide film based on vacuum interconnection according to any one of claims 1 to 9, include: Prepare transition metal crystal materials or metal materials for polishing interfaces, prepare carbon source gas, perform controllable carbonization under protective conditions, and then perform ultra-high vacuum annealing to remove impurities.

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