WO2020087888A1 - 一种检测柱状自组装薄膜结构的方法及其制备方法 - Google Patents

一种检测柱状自组装薄膜结构的方法及其制备方法 Download PDF

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WO2020087888A1
WO2020087888A1 PCT/CN2019/084013 CN2019084013W WO2020087888A1 WO 2020087888 A1 WO2020087888 A1 WO 2020087888A1 CN 2019084013 W CN2019084013 W CN 2019084013W WO 2020087888 A1 WO2020087888 A1 WO 2020087888A1
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substrate
film
interface
thin film
binding energy
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PCT/CN2019/084013
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French (fr)
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姜杰
杨琼
周益春
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湘潭大学
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B1/00—Devices without movable or flexible elements, e.g. microcapillary devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
    • B81B7/04—Networks or arrays of similar microstructural devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
    • B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
    • B81C1/00023—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems without movable or flexible elements
    • B81C1/00031—Regular or irregular arrays of nanoscale structures, e.g. etch mask layer

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  • the invention relates to the technical field of film and device preparation, in particular to a method for detecting a columnar self-assembled film structure and a preparation method thereof.
  • the object of the present invention is to provide a method for detecting a columnar self-assembled thin film structure and a preparation method thereof by constructing material A and the most stable interface structure a with the substrate, and material B and the most stable interface structure b with the substrate;
  • the technician can determine whether the thin film of the structure is needed according to the above calculation results. If it is, the technician prepares a large amount of it. If it is not, the preparation is not required, and multiple experiments can be avoided; meanwhile, the technician can According to the interface of the material, the required material structure can be designed, which saves time and material.
  • the first aspect of the present invention provides a method for detecting a straight columnar self-assembled thin film structure, including: using a first-principle method to construct a material A and the most stable interface structure a with a substrate, respectively, and materials B and the most stable interface structure b with the substrate; calculate the interface binding energy (E fA ) of the interface structure a and the interface binding energy (E fB ) of the interface structure b; calculate the interface binding energy (E fA ) and interface binding energy (E fB ), if the difference is greater than zero, in the structure of the columnar self-assembled film formed by material A and material B, material A is a nano-pillar material and material B is a matrix material; The difference is less than zero. In the structure of the columnar self-assembled film formed by material A and material B, material B is a nano-pillar material and material A is a matrix material.
  • the conditions of the first-principles method are: the use of projection-embedded pseudo-potential PAW, the generalized gradient approximation GGA in the electron exchange correlation functional PBE, and the plane wave truncation energy of 450 eV;
  • the modified tetrahedron method optimizes all the data obtained by the first principle, and the value of K point in the optimization process is 3 ⁇ 3 ⁇ 1.
  • the A material, the B material and the substrate have a single crystal structure; preferably, the A material and / or the B material are multiferroic materials; the A material and / or the B material are ferromagnetic materials.
  • Another aspect of the present invention provides a method for preparing a columnar self-assembled thin film, which includes: calculating and determining the structure of the thin film to be prepared using the above method; using a pulsed laser deposition dual-target alternate growth system to continuously strike nanopillar materials After m times, the base material is struck n times in succession, and the m and n times of striking constitute a striking cycle; multiple striking cycles are performed to control the thickness of each cycle formed on the substrate to be less than one of the A material and the B material. Single cell height.
  • the pulse laser deposition dual-target alternating growth system before the pulse laser deposition dual-target alternating growth system is used to strike the nano-pillar material continuously for m times, it also includes: using the pulse laser deposition system to grow a layer of epitaxial oxide bottom electrode with a thickness of 10-50 nm on the substrate.
  • the structure of the formed vertical columnar self-assembled film can be determined in advance, and the vertical columnar self-assembled film can be selectively prepared, saving Preparation of materials, improve preparation efficiency.
  • the first-principle method of calculating the interface binding energy of the two provides prediction and experimental guidance for the crystal structure of the self-assembled thin film.
  • FIG. 1 is a schematic flowchart of a method for detecting a columnar self-assembled thin film structure provided by an embodiment of the present invention
  • FIG. 2 is a schematic diagram of two interface structures constructed according to the first embodiment of the present invention.
  • FIG. 3 is a schematic flowchart of a method for preparing a columnar self-assembled film according to a second embodiment of the present invention
  • FIG. 4 is a schematic structural view of a columnar self-assembled film prepared according to the second embodiment
  • FIG. 5 is a schematic diagram of preparing an epitaxial oxide bottom electrode according to the second embodiment
  • FIG. 6 is a schematic structural view of an apparatus for preparing a vertical columnar self-assembled film according to a second embodiment of the present invention.
  • FIG. 7 is a schematic diagram of two interface structures constructed in the third embodiment of the present invention.
  • FIG. 8 is a schematic diagram of constructing two interface structures according to the fourth embodiment of the present invention.
  • FIG. 1 is a schematic flowchart of a method for detecting a columnar self-assembled thin film structure provided by an embodiment of the present invention.
  • the method includes steps S101-S103;
  • step S101 a first-principle method is used to respectively construct material A and the most stable interface structure a with the substrate, and material B and the most stable interface structure b with the substrate.
  • a materials, B materials and substrate materials There may be many interfaces constructed by A materials, B materials and substrate materials. Calculate the various interface binding energies constructed by A materials, B materials and substrate materials separately, and select the lowest interface binding energy among the various interface binding energies. As the most stable interface structure a and the most stable interface structure b, then take the most stable interface structure a and the most stable interface structure b as the research object.
  • a mathematical model is established by a computer.
  • the mathematical model is a mathematical model of how the two materials and the atoms, atomic bonds, and spatial structures in the substrate are displayed.
  • the crystal structure and lattice parameters, the crystal structure and lattice parameters of the material B, and the crystal structure and lattice parameters of the substrate are constructed by the technician by operating the computer, and the interface structure formed by the material A and the substrate material may exist, and the construction may exist.
  • the interface structure formed by the material B and the substrate material are constructed by the technician by operating the computer.
  • step S102 the interface binding energy (E fA ) of the interface structure a and the interface binding energy (E fB ) of the interface structure b are calculated respectively.
  • the crystal structure mismatch between the A material and the substrate in the reference database model is 1%, and the corresponding strain generated during the actual growth corresponds to a lattice mismatch of 2%, so in calculating E A (thin film / Substrate), adjust the lattice parameters of the A material so that the lattice mismatch reaches 2%.
  • the crystal structure mismatch between the B material and the substrate in the reference database model is 1%, and the lattice mismatch corresponding to the corresponding strain generated during the actual growth process is 2%, so in calculating E B (thin film / Substrate), adjust the lattice parameters of the B material so that the lattice mismatch reaches 2%.
  • the conditions of the first-principle method described above are: the use of projection-embedded wave pseudopotential PAW, electronic exchange correlation functional PBE, and plane wave truncation energy of 450 eV;
  • the modified tetrahedron method optimizes all the data obtained by the first principle, and the value of K point in the optimization process is 3 ⁇ 3 ⁇ 1. In other words, in the optimization process, the number of K points used in the three directions of X, Y, and Z is 3, 3, and 1, respectively.
  • the plane wave basis set is used to expand the electron wave function outside the atomic nucleus, since the inner layer electrons are bound to the core of the atomic nucleus, this requires a very large basis set to obtain a good approximation.
  • the chemical properties of a substance are mainly influenced by valence electrons outside the nucleus.
  • the interaction between the inner electrons and the electrons outside the other nucleus is relatively weak, resulting in little change in the influence of the inner electrons outside the nucleus on the chemical properties.
  • a hypothetical electrostatic potential is used to replace the electric potential generated by the electrons at the atomic core, which reduces the number of electrons and the size of the base group that need to be calculated, greatly reducing the amount of calculation, making this method possible Simulate a larger computing system.
  • This imaginary electrostatic potential is called a pseudopotential.
  • the truncation energy is a plane wave representing how much energy is taken after the plane wave is expanded. For the high-energy part, the proportion after expansion is very small, and it affects the calculation speed, so it is not that the larger the truncation energy, the better.
  • the truncated energy is the energy that separates the valence state electrons from the core (core state) electrons in the calculation of the pseudopotential.
  • the purpose of the pseudopotential is to get a potential to best describe its behavior on valence state electrons, so how to choose the valence state and core state has an essential effect on the pseudopotential behavior.
  • the radius of the nuclear zone (truncating radius) is used to truncate the wave function of the electrons in the nuclear zone, so-called matchradii. This radius selection directly affects the behavior of generating pseudopotentials.
  • LDA is based on an ideal uniform electron gas model, and the electron density of actual atoms and molecular systems is far from uniform, the chemical properties of atoms or molecules usually calculated by LDA often cannot meet the requirements of chemists. To further improve the calculation accuracy, it is necessary to consider the non-uniformity of the electron density, which is generally accomplished by introducing the gradient of the electron density in the exchange correlation energy function, that is, the generalized gradient approximates GGA.
  • Step S103 calculating the difference between the interface binding energy (E fA ) and the interface binding energy (E fB ). If the difference is greater than zero, the material A is formed as a nano-pillar embedded in the material B; if the difference is less than zero, Then, material B is formed as a nano-pillar embedded in material A. If the difference is equal to zero, the self-assembled film cannot be formed, and it will become a layer of film or a layer of two materials mixed together.
  • material A is a nanopillar material (Pillar) and material B is a matrix material (Matrix); if the difference Less than zero, in the structure of the columnar self-assembled film formed by material A and material B, material B is a nano-pillar material and material A is a matrix material.
  • the A material, the B material and the substrate are all single crystal structures, and the A material and the B material do not melt with each other.
  • the atomic frame structure of the A material cannot form another atomic frame with the atomic frame structure of the B material.
  • Structure assuming that the atomic structure of A is a cuboid and the atomic structure of B is a cuboid.
  • a and B will not form another irregular atomic structure.
  • the A material and / or the B material are ferroelectric materials or ferromagnetic materials. If the A material, the B material and the substrate are not single crystal structures, then vertical columnar self-assembled thin films cannot be prepared.
  • the method for detecting the structure of the columnar self-assembled film provided by the embodiment of the present invention can determine the structure of the formed vertical columnar self-assembled film in advance, and can selectively prepare the columnar self-assembled film, saving the preparation materials and improving the preparation effectiveness.
  • FIG. 2 is a schematic diagram of two interface structures constructed in the first embodiment of the present invention.
  • the multi-iron material bismuth ferrite BiFeO 3 and the dielectric material cerium oxide CeO 2 are used as the preparation materials of the thin film, and the (001) direction strontium titanate SrTiO 3 is used as the substrate as an example for detailed discussion , but the invention is not limited to this. Since bismuth ferrite BiFeO 3 and cerium oxide CeO 2 have no conductive properties, electrical tests cannot be directly conducted. An epitaxial oxide bottom electrode needs to be added between BiFeO 3 , CeO 2 and the substrate. At this time, the epitaxial oxide bottom electrode directly contacts BiFeO 3 and CeO 2. Therefore, the epitaxial bottom electrode is equivalent to a layer of substrate. When calculating the interface structure, the epitaxial oxide bottom electrode and BiFeO 3 and CeO 2 need to be calculated. Interface structure. In this embodiment, the strontium oxide bottom electrode takes strontium ruthenate SrRuO 3 as an example.
  • Bismuth iron left BiFeO 3 a schematic view of the most stable interface structure SrRuO 3 with strontium ruthenate
  • the right side is a schematic view of the most stable interface structure SrRuO 3 ceria CeO 2 with strontium ruthenate.
  • Iron bismuth strontium ruthenium BiFeO 3 and SrRuO 3 interface capable of binding to binding cerium oxide CeO 2 with strontium ruthenate substrate interface SrRuO 3 can be a difference of 1.52> 0.
  • FIG. 3 is a schematic flowchart of a method for preparing a columnar self-assembled film according to a second embodiment of the present invention.
  • the method includes steps S201-S203.
  • the multi-ferrous material BiFeO 3 and the dielectric material cerium oxide CeO 2 are used as the preparation materials of the thin film, and the (001) direction strontium titanate SrTiO 3 is selected as the substrate as an example for detailed discussion.
  • 3 and cerium oxide CeO 2 have no electrical conductivity, so electrical testing cannot be performed directly, and an epitaxial oxide bottom electrode needs to be added between BiFeO 3 , CeO 2 and the substrate.
  • the epitaxial oxide bottom electrode directly contacts BiFeO 3 and CeO 2. Therefore, when calculating the interface structure, it is necessary to calculate the interface structure of the epitaxial oxide bottom electrode and BiFeO 3 and CeO 2 .
  • the epitaxial oxide bottom electrode uses strontium ruthenate SrRuO 3 as an example.
  • the generated vertical columnar self-assembled film has conductivity and can be electrically tested, there is no need to prepare a layer of epitaxial bottom electrode on the substrate.
  • pulsed laser deposition system needs a substrate (001) SrTiO 3 grown to a thickness of 10 ⁇ 50nm was epitaxial strontium ruthenium bottom electrode SrRuO 3.
  • the growth conditions of the epitaxial bottom electrode strontium ruthenate SrRuO 3 are: frequency 10 Hz, laser energy 300 mJ, target-substrate distance 40 mm, oxygen pressure 70-150 mTorr, temperature 650-720 ° C., growth time 20 minutes .
  • the oxygen pressure is 100 mTorr, the temperature is 690 ° C., and the thickness is 20 nm.
  • Oxygen pressure If the oxygen pressure is too low, it will make it lack of oxygen and change the crystal structure. If the oxygen pressure is too high, the surface structure of strontium ruthenate SrRuO 3 becomes rough and the growth rate becomes slow. If the temperature is too low, crystallization is incomplete, and if the temperature is too high, the crystal structure of strontium ruthenate SrRuO 3 will be destroyed, and resources will be wasted. If the thickness is too low, the conductivity is not good, and if the thickness is too high, resources are wasted.
  • Step S201 a pulsed laser deposition dual-target alternating growth system is used to continuously strike the nano-pillar material m times, and then the substrate material is continuously hit n times, and the m and n times of the strike constitute a cyclic strike.
  • the nano-pillar material bismuth ferrite BiFeO 3 is successively struck m times, and then the matrix material cerium oxide CeO 2 is continuously struck n times, and the m and n times of the striking constitute a cyclic striking.
  • step S202 a cyclic strike is carried out multiple times, and a thin film with a preset thickness is grown on the strontium ruthenate SrRuO 3 layer, wherein the thickness formed on the strontium ruthenate SrRuO 3 in each cycle is controlled to be smaller than that of ferric acid A unit cell height of bismuth BiFeO 3 and ceria CeO 2 .
  • the thickness of the single-cycle strike is very important for the influence of the film. If the thickness is too thick, a vertical columnar film will not be formed. Therefore, the thickness of a single-cycle strike cannot exceed the height of a single cell of the two materials.
  • the distance between the target bismuth ferrite BiFeO 3 and the target cerium oxide CeO 2 to the substrate are 40 mm; the frequency is 10 Hz; the laser energy is 300 mTorr.
  • the temperature of the cyclic strike is 600-700 ° C, preferably 650 ° C; oxygen
  • the pressure is 70-150 mTorr, preferably oxygen pressure 100 mTorr; the ratio of n to m is in the range of 5: 75-5: 300, preferably 5: 200.
  • the temperature of the cyclic blow is lower than 600 ° C, the two materials cannot crystallize well; if the temperature of the cyclic blow is higher than 700 ° C, Bi in the vertical columnar self-assembled film formed by BiFeO 3 volatilizes, the crystal structure and iron The electrical performance will be poor.
  • step S203 a large amount of oxygen is continuously supplied to control the cooling rate of the film not to exceed 0.4 ° C / s until the film is cooled to room temperature.
  • the rapid oxygen supply to the film for oxygen supplementation is mainly to reduce the oxygen vacancies in the film, thereby reducing the film leakage and improving the ferroelectric performance of the film.
  • the vertical columnar thin film prepared by the above method can be applied to the field of ferroelectric memory. Since the ferroelectric material is embedded as nanocolumns in cerium oxide CeO 2 , the storage density of the ferroelectric memory can be greatly increased.
  • FIG. 4 is a schematic structural view of a columnar self-assembled film prepared according to the second embodiment.
  • the formation process of the vertical columnar self-assembled thin film is: the double-target alternating growth system by pulse laser deposition strikes bismuth ferrite BiFeO 3 (abbreviated as BFO in the figure) and cerium oxide CeO 2 alternately, making A layer of BFO-CeO 2 vertical columnar self-assembled film is formed on the epitaxial bottom electrode strontium ruthenate SrRuO 3 (abbreviated as SRO in the figure).
  • SRO strontium ruthenate
  • bismuth ferrite BiFeO 3 forms vertical nanocolumns embedded in ceria CeO 2 in.
  • FIG. 5 is a schematic diagram of preparing an epitaxial oxide bottom electrode according to the second embodiment.
  • the control pulse laser deposition system the laser beam hit (abbreviated as SRO) on the surface of the target exposed to the laser spot strontium ruthenium SrRuO 3 strontium ruthenium target surface by the laser beam of high SrRuO 3 Density energy is ablated and evaporated, and the target particles and droplets at high temperature encounter high-energy laser light again in the air to form a bright center-like flame-like strontium ruthenate SrRuO 3 plume, which is deposited on the plume under the action of an external laser SrTiO 3 on the substrate (001) directly below.
  • SRO the laser beam hit
  • FIG. 6 is a schematic structural view of an apparatus for preparing a vertical cylindrical self-assembled film according to a second embodiment of the present invention.
  • the control pulse laser deposition dual target system the laser beam hit the target bismuth ferrate BiFeO 3 n, so that 3 is grown on the strontium ruthenium SrRuO 3 BiFeO bismuth iron portion; rotatable targets exchanger
  • the laser beam hits the CeO 2 target m times, and a part of CeO 2 is grown on the strontium ruthenate SrRuO 3 . Repeated strikes multiple times to form a vertical columnar self-assembled film on the surface of the epitaxial bottom electrode strontium ruthenate SrRuO 3 .
  • the BFO-CeO 2 vertical columnar self-assembled film obtained by the apparatus for preparing a vertical columnar self-assembled film provided in the embodiments of the present invention can be used in a ferroelectric memory, and the nano-pillars in the self-assembled nanostructures are used as ferroelectric materials. A large increase in storage density can be achieved. At the same time, the ferroelectric nanopillars formed by the vertical self-assembled heteroepitaxial nanostructures can be directly used as functional elements, avoiding potential damage during the photo-etching process.
  • FIG. 7 is a schematic diagram of two interface structures constructed in the third embodiment of the present invention.
  • the multiferroic material bismuth ferrite BiFeO 3 and the ferromagnetic material cobalt ferrite CoFe 2 O 4 are used as the thin film preparation materials, and the (001) direction strontium titanate SrTiO 3 is selected as the substrate as an example A detailed discussion is made, but the invention is not limited to this. Since bismuth ferrite BiFeO 3 and cobalt ferrite CoFe 2 O 4 have no conductive properties, electrical tests cannot be directly conducted, and an epitaxial oxide bottom electrode needs to be added between BiFeO 3 , CoFe 2 O 4 and the substrate. At this time, the epitaxial oxide bottom electrode directly contacts BiFeO 3 and CoFe 2 O 4.
  • the epitaxial bottom electrode is equivalent to a layer of substrate.
  • the strontium oxide bottom electrode takes strontium ruthenate SrRuO 3 as an example.
  • Bismuth iron right BiFeO 3 (referred to as the BFO) is a schematic view of the most stable interface structure SrRuO 3 (referred to as SRO) and strontium ruthenate, the left cobalt ferrite CoFe 2 O 4 (referred CFO) and strontium ruthenate SrRuO 3 Schematic diagram of the most stable interface structure.
  • Cobalt ferrite CoFe 2 O 4 / strontium ruthenium SrRuO 3 interface capable of binding with bismuth ferrite BiFeO 3 / strontium ruthenium SrRuO 3 interface binding energy difference is 0.79> 0. Therefore, it can be concluded that cobalt ferrite CoFe 2 O 4 will form a vertical columnar self-assembled film composed of BiFeO 3 , cobalt ferrite CoFe 2 O 4 and strontium ruthenate (001) SrRuO 3 substrates. The column is embedded in BiFeO 3 bismuth ferrite.
  • cobalt ferrite CoFe 2 O 4 and bismuth ferrite BiFeO 3 cobalt ferrite CoFe 2 O 4 is a nano-pillar material
  • bismuth ferrite BiFeO 3 is a matrix material
  • strontium ruthenate (001) SrRuO 3 is an epitaxial material
  • the preparation method of the vertical columnar self-assembled thin film of the bottom electrode is the same as the preparation method of the second embodiment above, so it will not be described in detail.
  • the vertical columnar self-assembled long thin film structure prepared by the method of Example 3 can significantly improve the ferromagnetism compared with the two thin films formed by cobalt ferrite CoFe 2 O 4 or bismuth ferrite BiFeO 3 alone. can.
  • the multiferroic material bismuth ferrite BiFeO 3 and the ferromagnetic material cobalt ferrite CoFe 2 O 4 are used as the preparation materials of the thin film, and the (111) direction strontium titanate SrTiO 3 is used as the substrate for an example.
  • Bismuth acid BiFeO 3 and CoFe 2 O 4 have no electrical conductivity, so electrical testing cannot be performed directly.
  • An epitaxial oxide bottom electrode needs to be added between BiFeO 3 , CoFe 2 O 4 and the substrate. At this time, the epitaxial oxide bottom electrode directly contacts BiFeO 3 and CoFe 2 O 4. Therefore, the epitaxial bottom electrode is equivalent to a layer of substrate.
  • the bottom oxide electrode is an example of strontium ruthenate (111) SrRuO 3 .
  • the left bismuth ferrate (111) BiFeO 3 with strontium ruthenate (111) the most stable SrRuO 3 a schematic view of the interface structure, the right side is cobalt ferrite (111) CoFe 2 O 4 with strontium ruthenate (111) SrRuO 3 Schematic diagram of the most stable interface structure.
  • Bismuth ferrate (111) BiFeO 3 / strontium ruthenate (111) SrRuO 3 binding interface can CoFe 2 O 4 / strontium ruthenate (111) SrRuO 3 interface combination with cobalt ferrite (111) can be a difference of 2.79> 0. Therefore, in the vertical columnar self-assembled thin film composed of bismuth ferrite BiFeO 3 , cobalt ferrite CoFe 2 O 4 and strontium ruthenate (111) SrRuO 3 substrate, cobalt ferrite CoFe 2 O 4 will form a vertical column embedded in iron Bismuth acid BiFeO 3 .
  • cobalt ferrite CoFe 2 O 4 and bismuth ferrite BiFeO 3 cobalt ferrite CoFe 2 O 4 is a nano-pillar material
  • bismuth ferrite BiFeO 3 is a matrix material
  • strontium ruthenate (111) SrRuO 3 is an epitaxial material
  • the preparation method of the vertical columnar self-assembled thin film of the bottom electrode is the same as the preparation method of the second embodiment above, so it will not be described in detail.
  • the BFO-CFO vertical columnar self-assembled thin film obtained by the device for preparing the vertical columnar self-assembled thin film provided by the method provided in Example 4 of the present invention can obtain the magnetoelectric coupling effect (ME Effect), and separate cobalt ferrite CoFe 2 O 4 or the two thin films formed by BiFeO 3 alone can significantly improve the ferromagnetic performance, and can be used in electronic devices.
  • ME Effect magnetoelectric coupling effect
  • the selection of strontium titanate SrTiO 3 in different directions as the substrate will result in completely different interface binding energy, so that the same two substances grow on the substrate in different directions.
  • the formed vertical columnar self-assembled structure is completely different, which further verifies that the structure of the formed vertical columnar self-assembled film can be predetermined by adopting the method for detecting the columnar self-assembled film structure provided by the embodiment of the present invention
  • Selective preparation of columnar self-assembled films saves preparation materials and improves preparation efficiency.

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Abstract

一种检测柱状自组装薄膜结构的方法，包括：分别构建材料A和与基板最稳定的界面结构a，以及材料B和与基板最稳定的界面结构b；分别计算界面结构a的界面结合能(EfA)，以及界面结构b的界面结合能(EfB)；计算界面结合能(EfA)与界面结合能(EfB)的差值，若差值大于零，则材料A形成为纳米柱镶嵌在材料B中；若差值小于零，则材料B形成为纳米柱镶嵌在材料A中。采用判断竖直柱状自组装薄膜结构的方法能够预先确定所形成的竖直柱状自组装薄膜的结构，可以有选择性的制备竖直柱状自组装薄膜，节省了制备材料，提高了制备效率。

Description

一种检测柱状自组装薄膜结构的方法及其制备方法
本申请基于申请号为201811299980.4、申请日为2018年11月2日的中国专利申请提出，并要求该中国专利申请的优先权，该中国专利申请的全部内容在此引入本申请作为参考。
技术领域
本发明涉及薄膜与器件制备技术领域，尤其是涉及一种检测柱状自组装薄膜结构的方法及其制备方法。
背景技术
随着电子器件的快速发展，器件的小型化和多功能性成为了下一代电子设备的发展方向。为了实现器件的小型化，同时开发得到更多的新性能，科学家们将多个物理属性集成到一个系统中并对其进行大量探索。其中，很多科研工作人员发现竖直自组装的异质外延纳米结构：把纳米柱材料嵌入在另一种材料的基质中，令人兴奋的是这种结构时常表现出令人感兴趣的性能，如磁电耦合效应(ME Effect)、磁阻效应(MR Effect)和光电电化学性能等等。基于此，竖直状自组装的异质外延纳米结构是非常值得研究的。但是，目前在本领域中，还没有哪一种方法能够预测材料A和材料B所形成的竖直状自组装薄膜中，哪一材料会形成纳米柱。
发明内容
本发明的目的是提供一种检测柱状自组装薄膜结构的方法及其制备方法，通过构建材料A和与基板最稳定的界面结构a，以及材料B和与基板最稳定的界面结构b；计算界面结构a的界面结合能(E fA)，以及界面结构b的界面结合能(E fB)；根据界面结合能(E fA)与界面结合能(E fB)的大小确定A材料和B材料哪一种形成为竖直纳米柱，哪一种形成为基材，能够准确检测所形成的柱状薄膜的结构。技术人员可以根据上述计算结果确定该结构的薄膜是不是 所需要的，如果是则技术人员对其进行大量制备，如果不是，就不需要进行制备，可以避免多次实验；同时，技术人员还可以根据材料的界面结合能设计所需的材料结构，在节约时间的同时节省了材料。
为解决上述问题，本发明的第一方面提供了一种检测直柱状自组装薄膜结构的方法，包括：采用第一性原理的方法分别构建材料A和与基板最稳定的界面结构a，以及材料B和与基板最稳定的界面结构b；分别计算界面结构a的界面结合能(E fA)，以及界面结构b的界面结合能(E fB)；计算界面结合能(E fA)与界面结合能(E fB)的差值，若所述差值大于零，则由材料A和材料B所形成的柱状自组装薄膜的结构中，材料A为纳米柱材料，材料B为基体材料；若所述差值小于零，由材料A和材料B所形成的柱状自组装薄膜的结构中，材料B为纳米柱材料，材料A为基体材料。
进一步地，界面结合能(E fA)的计算步骤包括：采用第一性原理的方法分别计算：A材料形成的薄膜和基板完全弛豫后最稳定时的总能量E A(薄膜/基板)、A材料形成的薄膜完全自由时的总能量E A(薄膜)、基板完全自由时的总能量E(基板)；根据公式计算界面结合能(E fA)，其中，公式为：界面结合能(E fA)＝[E A(薄膜/基板)-E A(薄膜)-E(基板)]/界面面积。
进一步地，界面结合能(E fB)的计算步骤包括：采用第一性原理的方法分别计算：B材料形成的薄膜和基板完全弛豫后最稳定时的总能量E B(薄膜/基板)、B材料形成的薄膜完全自由时的总能量E B(薄膜)、基板完全自由时的总能量E(基板)；根据公式计算界面结合能(E fA)，其中，公式为：界面结合能(E fA)＝[E A(薄膜/基板)-E A(薄膜)-E(基板)]/界面面积。
进一步地，第一性原理的方法的条件为：采用投影缀加波赝势PAW、电子交换关联泛函PBE中的广义梯度近似GGA和平面波截断能为450eV；其中，采用
Figure PCTCN2019084013-appb-000001
修正的四面体方法对第一性原理获得的全部数据进行优化处理，优化过程中K点的取值为3×3×1。
进一步地，A材料、B材料和基板为单晶结构；优选的，A材料和/或B材料为多铁材料；A材料和/或B材料为铁磁材料。
本法发明的另一方面，提供了一种制备柱状自组装薄膜的方法，包括：采用上述方法计算并确定待制备的薄膜的结构；采用脉冲激光沉积双靶交替生长系统对纳米柱材料连续打击m次后，对基体材料连续打击n次，打击的m次和n次构成一个打击循环；多次进行循环打击，控制每个循环在基板上所形成的厚度同时小于A材料和B材料的一个单胞高度。
进一步地，采用脉冲激光沉积双靶交替生长系统对纳米柱材料连续打击m次之前，还包括：采用脉冲激光沉积系统在基板上生长一层厚度为10～50nm的外延氧化物底电极。
本发明的上述技术方案具有如下有益的技术效果：
(1)采用本发明实施例提供的判断竖直柱状自组装薄膜结构的方法能够预先确定所形成的竖直柱状自组装薄膜的结构，可以有选择性的制备竖直柱状自组装薄膜，节省了制备材料、提高制备效率。
(2)采用第一性原理计算两个的界面结合能的方法为自组装薄膜的晶体结构提供了预测和实验指导。
附图说明
图1是本发明一实施方式提供的检测柱状自组装薄膜结构的方法流程示意图；
图2是根据本发明第一实施例中构建的两种界面结构示意图；
图3是根据本发明第二实施例中制备柱状自组装薄膜的方法流程示意图；
图4是根据第二实施例制备的柱状自组装薄膜的结构示意图；
图5是根据第二实施例制备外延物氧化物底电极的示意图；
图6是根据本发明第二实施例制备竖直柱状自组装薄膜的装置结构示意图；
图7是根据本发明第三实施例中构建的两种界面结构示意图；
图8是根据本发明第四实施例中构建两种界面结构的示意图。
具体实施方式
为使本发明的目的、技术方案和优点更加清楚明了，下面结合具体实施方式并参照附图，对本发明进一步详细说明。应该理解，这些描述只是示例性的，而并非要限制本发明的范围。此外，在以下说明中，省略了对公知结构和技术的描述，以避免不必要地混淆本发明的概念。
图1是本发明一实施方式提供的检测柱状自组装薄膜结构的方法流程示意图。
如图1所示，该方法包括步骤S101-步骤S103；
步骤S101，采用第一性原理的方法分别构建材料A和与基板最稳定的界面结构a，以及材料B和与基板最稳定的界面结构b。
A材料、B材料与基板材料所构建的界面可能有很多中，分别计算A材料、B材料与基板材料所构建的多种界面结合能，分别在多种界面结合能中选择界面结合能最低的作为最稳定的界面结构a和最稳定的界面结构b，然后以最稳定的界面结构a和最稳定的界面结构b为研究对象。
需要说明的是，通过计算机建立一个数学模型，该数学模型是关于两种材料以及基板中的各个原子、原子键、以及空间结构等等是如何展现的数学模型，通过在电脑上输入A材料的晶体结构及晶格参数、B材料的晶体结构及晶格参数以及基板的晶体结构及晶格参数，由技术人员通过操作计算机，构建可能存在材料A与基板材料形成的界面结构，以及构建可能存在的材料B与基板材料形成的界面结构。
步骤S102，分别计算界面结构a的界面结合能(E fA)，以及界面结构b的界面结合能(E fB)。
具体地，界面结合能(E fA)的计算步骤包括：采用第一性原理的方法分别计算：A材料形成的薄膜和基板完全弛豫后最稳定时的总能量E A(薄膜/基板)、A材料形成的薄膜完全自由时的总能量E A(薄膜)、基板完全自由时的总能量E(基板)；根据公式计算界面结合能(E fA)，其中，公式为：界面结合能(E fA)＝[E A(薄膜/基板)-E A(薄膜)-E(基板)]/界面面积。
需要说明的是，采用第一性原理计算上述多个能量值时，由于材料A和基板的晶格常数会有稍许不同，所以材料A和基板之间会存在一定的晶格失配现象，而晶格失配现象会使制备出来的薄膜产生一定的应变，所以在计算E A(薄膜/基板)时，需通过在薄膜上调整材料A的晶格参数以使A材料和基底所形成的应变与实验结果得到的应变相一致。调整材料A的晶格参数时，可以查找参考文献即可获得相应的实验中的应变。比如说，参考数据库模型中的A材料和基板的晶体结构失配是1％，而实际生长的过程中产生相应的应变所对应的晶格失配是2％，所以在计算E A(薄膜/基板)时，调整A材料的晶格参数，使得晶格失配达到2％。
还需要说明的是，完全弛豫的是从某一个状态逐渐地恢复到平衡态的过程。这里指初始时通过计算把材料和基板结合在一起，但是，在计算的过程中，计算机会自动调节搭建的原子键位置，该原子的相对位置会稍微改变，最后结合的结构不再是技术人员通过计算机搭建的位置，从开始技术人员搭建的状态进入一个相对平衡的状态。具体地，界面结合能(E fB)的计算步骤包括：采用第一性原理的方法分别计算：B材料形成的薄膜和基板完全弛豫后最稳定时的总能量E B(薄膜/基板)、B材料形成的薄膜完全自由时的总能量E B(薄膜)、基板完全自由时的总能量E(基板)；根据公式计算界面结合能(E fB)，其中，公式为：界面结合能(E fB＝[E B(薄膜/基板)-E B(薄膜)-E(基板)]/界面面积。
需要说明的是，采用第一性原理计算上述多个能量值时，由于材料B和基板的晶格常数会有稍许不同，所以材料B和基板之间会存在一定的晶格失配现象，而晶格失配现象会使制作出来的薄膜产生一定的应变，所以在计算E B(薄膜/基板)时，需通过在弛豫薄膜上调整材料B的晶格参数以使B材料和基底所形成的应变与实验结果得到的应变相一致。调整B材料的晶格参数时，可以查找参考文献即可获得相应的实验中的应变。比如说，参考数据库模型中的B材料和基板的晶体结构失配是1％，而实际生长的过程中产生相应的应变所对应的晶格失配是2％，所以在计算E B(薄膜/基板)时，调整B材料的晶格参数，使得晶格失配达到2％。上述采用第一性原理的方法的条件为： 采用投影缀加波赝势PAW、电子交换关联泛函PBE和平面波截断能为450eV；其中，采用
Figure PCTCN2019084013-appb-000002
修正的四面体方法对第一性原理获得的全部数据进行优化处理，优化过程中K点的取值为3×3×1。也就是说，优化过程中，X、Y、Z三个方向上分别用了K点的个数为3、3、1个。
需要说明的是，在使用平面波基组对原子核外的电子波函数进行展开时，由于内层电子被束缚在原子核的芯处，这就需要非常大的基组才能获得较好的近似。而通常物质的化学性质主要是受到原子核外的价电子的影响，内层电子与其他原子核外的电子相互作用比较弱，导致原子核外的内层电子对化学性质影响的变化不大。此时，用一个假想的静电势来替代原子芯处的电子所产生的电势，这就降低了所需要计算的电子的数量以及基组的大小，大大降低了计算量，使得采用此种方法可以模拟更大的计算体系。这个假想的静电势被称为赝势。
截断能是表示平面波展开后取到多大能量的平面波，对于高能部分，展开后所占的比例非常小，而且影响计算速度，所以并不是截断能越大越好。截断能是在计算赝势中把价态电子和核(芯态)电子分开(cut off)的能量。赝势的目的就是得到一个势来最好地描述其对价态电子的行为,因此如何选择价态与芯态对赝势行为有本质的影响.在确定了价态与芯态之后,我们需要选择核区半径(截断半径)来截断核区电子的波函数,也就是所谓match radii,这个半径选取直接影响生成赝势的行为。
由于LDA是建立在理想的均匀电子气模型基础上，而实际原子和分子体系的电子密度远非均匀的，所以通常由LDA计算得到的原子或分子的化学性质往往不能够满足化学家的要求。要进一步提高计算精度，就需要考虑电子密度的非均匀性，这一般是通过在交换相关能泛函中引入电子密度的梯度来完成，即广义梯度近似GGA。
步骤S103，计算界面结合能(E fA)与界面结合能(E fB)的差值，若该差值大于零，则材料A形成为纳米柱镶嵌在材料B中；若该差值小于零，则材料B形成为纳米柱镶嵌在材料A中。若该差值等于零，则无法形成自组装薄膜， 就会成为一层的薄膜或者得到的是两种材料混合在一起的一层薄膜。
也就是说，若差值大于零，则由材料A和材料B所形成的柱状自组装薄膜的结构中，材料A为纳米柱材料(Pillar)，材料B为基体材料(Matrix)；若差值小于零，由材料A和材料B所形成的柱状自组装薄膜的结构中，材料B为纳米柱材料，材料A为基体材料。
需要说明的是，A材料、B材料和基板均为单晶结构，且A材料和B材料不互融，例如，A材料的原子框架结构不能和B材料的原子框架结构形成另一种原子框架结构，假设A的原子结构为正方体，B的原子结构为长方体，A和B不会形成另一种不规则的原子结构，关于不互融的A材料和B材料可通过查阅文献查询。优选的，A材料和/或B材料为铁电材料或铁磁材料。如果A材料、B材料和基板不是单晶结构，那么将无法制备出竖直柱状自组装薄膜。
本发明的上述技术方案具有如下有益的技术效果：
(1)采用本发明实施例提供的检测柱状自组装薄膜结构的方法能够预先确定所形成的竖直柱状自组装薄膜的结构，可以有选择性的制备柱状自组装薄膜，节省制备材料，提高制备效率。
(2)采用第一性原理分别计算两个材料的界面结合能的方法为自组装薄膜的晶体结构提供了预测和实验指导。
下面将结合具体的实施例详细说明一下上述方法的步骤。
实施例一
图2是根据本发明第一实施例中构建的两种界面结构示意图。
如图2所示，本实施例选择多铁材料铁酸铋BiFeO 3和介电材料氧化铈CeO 2为薄膜的制备材料、选择(001)方向的钛酸锶SrTiO 3为基板作为例子进行详细论述，但本发明并不以此为限。由于铁酸铋BiFeO 3和氧化铈CeO 2没有导电性能，因此无法直接进行电学测试，需要在BiFeO 3、CeO 2和基板之间增加一层外延氧化物底电极。此时，由外延氧化物底电极直接与BiFeO 3和CeO 2接触，因此，外延物底电极相当于一层基板，在计算界面结构时， 需要计算外延氧化物底电极与BiFeO 3和CeO 2的界面结构。本实施例外延氧化物底电极以钌酸锶SrRuO 3为例。
左侧为铁酸铋BiFeO 3与钌酸锶SrRuO 3的最稳定的界面结构示意图，右侧为二氧化铈CeO 2与钌酸锶SrRuO 3的最稳定的界面结构示意图。
分别计算上述两种的界面结合能，其中铁酸铋BiFeO 3与钌酸锶SrRuO 3的界面结合能为-1.81J/m 2，二氧化铈CeO 2与钌酸锶SrRuO 3的界面结合能为-3.33J/m 2。
铁酸铋BiFeO 3与钌酸锶SrRuO 3的界面结合能与二氧化铈CeO 2与基板钌酸锶SrRuO 3的界面结合能差值为1.52>0。因此，铁酸铋BiFeO 3、二氧化铈CeO 2与钌酸锶SrRuO 3构成的竖直柱状自组装薄膜中，铁酸铋BiFeO 3会形成竖直柱镶嵌在二氧化铈CeO 2中。
实施例二
图3是根据本发明第二实施例中制备柱状自组装薄膜的方法流程示意图。
如图3所示，该方法包括：步骤S201-步骤S203。
本实施例选择多铁材料铁酸铋BiFeO 3和介电材料氧化铈CeO 2为薄膜的制备材料、选择(001)方向的钛酸锶SrTiO 3为基板作为例子进行详细论述，由于铁酸铋BiFeO 3和氧化铈CeO 2没有导电性能，因此无法直接进行电学测试，需要在BiFeO 3、CeO 2和基板之间增加一层外延氧化物底电极。此时，由外延氧化物底电极直接与BiFeO 3和CeO 2接触，因此，在计算界面结构时，需要计算外延氧化物底电极与BiFeO 3和CeO 2的界面结构。本实施例中外延氧化物底电极以钌酸锶SrRuO 3为例。
需要说明的是，如果生成的竖直柱状自组装薄膜具有导电性，能够进行电学测试，可以不需要在基板上制备一层外延物底电极。
首先，需要采用脉冲激光沉积系统在基板(001)SrTiO 3上生长一层厚度为10～50nm外延物底电极钌酸锶SrRuO 3。外延物底电极钌酸锶SrRuO 3的生长条件为：频率10Hz，激光能量为300mJ，靶材到基板的距离为40mm，氧压为70～150mTorr，温度为650～720℃，生长时间为20分钟。
优选的，氧压为100mTorr，温度为690℃，厚度为20nm。氧压如果氧压太低，则会使其缺氧，使晶体结构发生变化。氧压太高，则会使钌酸锶SrRuO 3的表面结构变的粗糙，且生长速度变慢。温度过低，则结晶不完全，温度过高，则会破坏钌酸锶SrRuO 3的晶体结构，且浪费资源。厚度过低，则导电性不好，厚度过高，浪费资源。
步骤S201,采用脉冲激光沉积双靶交替生长系统对纳米柱材料连续打击m次，然后对基体材料连续打击n次，打击的m次和n次构成一个循环打击。
具体地，对纳米柱材料铁酸铋BiFeO 3连续打击m次，然后对基体材料二氧化铈CeO 2连续打击n次，打击的m次和n次构成一个循环打击。
步骤S202，多次进行循环打击，在钌酸锶SrRuO 3层上生长有预设厚度的薄膜，其中，循环打击过程中控制每个循环在钌酸锶SrRuO 3上所形成的厚度同时小于铁酸铋BiFeO 3和二氧化铈CeO 2的一个单胞高度。
需要说明的是，单次循环打击的厚度对于薄膜的影响至关重要，如果厚度过厚则不会形成竖直柱状的薄膜。因此单次循环打击所形成的厚度不能超过两种材料的一个单胞高度。
具体地，靶材铁酸铋BiFeO 3和靶材二氧化铈CeO 2到基板的距离均为40mm；频率为10Hz；激光能量为300mTorr循环打击的温度为600-700℃，优选为650℃；氧压为70-150mTorr，优选为氧压100mTorr；n与m的比例范围为：5:75-5:300，优选为5:200。
如果循环打击的温度低于600℃，则两种材料不能很好的结晶；如果循环打击的温度高于700℃则BiFeO 3形成的竖直柱状自组装薄膜中的Bi挥发，晶体的结构和铁电性能会很差。
还需要说明的是，n与m的比例范围超过5:75-5:300时，所制成的薄膜中两种材料的结构不够清楚。
步骤S203，持续通入大量氧气，控制薄膜的降温速度不超过0.4℃/s，直到薄膜冷却至室温。
具体地，当薄膜生长完成后，需迅速通入大量的氧气对薄膜进行补氧处 理，同时对薄膜进行降温处理，直到薄膜降温到室温(30℃左右)。控制薄膜周围的氧压为300mTorr，降温速度不超过0.4℃/s。迅速通入大量的氧气对薄膜进行补氧处理主要是为了减少薄膜中的氧空位，从而降低薄膜漏电，提高薄膜的铁电性能。
需要说明的是，薄膜生长完成后，如果降温的速度过快，薄膜的晶体中会产生应力，对薄膜的结构有影响，因此降温的速度不能超过0.4℃/s。
通过上述方法所制备的竖直柱状薄膜，可应用于铁电存储器领域，由于铁电材料作为纳米柱镶嵌在二氧化铈CeO 2中，可以实现铁电存储器存储密度的大幅度增加。
图4是根据第二实施例制备的柱状自组装薄膜的结构示意图。
如图4所示，竖直柱状自组装薄膜的形成过程为：通过脉冲激光沉积双靶交替生长系统对铁酸铋BiFeO 3(图中简称为BFO)和二氧化铈CeO 2交替打击，使得在外延物底电极钌酸锶SrRuO 3(图中简称为SRO)上形成有一层BFO-CeO 2竖直柱状自组装薄膜，该薄膜中铁酸铋BiFeO 3会形成竖直纳米柱镶嵌在二氧化铈CeO 2中。
图5是根据第二实施例制备外延物氧化物底电极的示意图。
如图5所示，控制脉冲激光沉积系统，使激光束打在钌酸锶SrRuO 3(简称为SRO)靶材的表面上，接触到激光光斑的钌酸锶SrRuO 3靶材表面因激光的高密度能量而被烧蚀蒸发，高温下的靶材颗粒、液滴在空中再次遇到高能的激光从而形成中心明亮类似火焰的钌酸锶SrRuO 3羽辉，在外加激光的作用下沉积在羽辉正下方的基板(001)SrTiO 3上。
图6是根据本发明第二实施例制备竖直柱状自组装薄膜的装置结构示意图。
如图6所示，控制脉冲激光沉积双靶系统，使激光束打在铁酸铋BiFeO 3靶材n下，使一部分铁酸铋BiFeO 3生长在钌酸锶SrRuO 3上；旋转靶材交换器，使激光束打CeO 2靶材m次，使一部分CeO 2生长在钌酸锶SrRuO 3上。重复打击多次，在外延物底电极的表面钌酸锶SrRuO 3上形成一层竖直柱状 自组装薄膜。
通过本发明实施例提供的制备竖直柱状自组装薄膜的装置得到的BFO-CeO 2竖直柱状自组装薄膜可以应用在铁电存储器中，把自组装纳米结构中的纳米柱作为铁电材料，可以实现存储密度的大幅度增加。同时这种竖直自组装的异质外延纳米结构形成的铁电纳米柱可直接作为功能元件，避免了光蚀刻过程的潜在损伤。
实施例三
图7是根据本发明第三实施例中构建的两种界面结构示意图。
如图7所示，本实施方式选择多铁材料铁酸铋BiFeO 3和铁磁材料铁酸钴CoFe 2O 4为薄膜的制备材料、选择(001)方向的钛酸锶SrTiO 3为基板作为例子进行详细论述，但本发明并不以此为限。由于铁酸铋BiFeO 3和铁酸钴CoFe 2O 4没有导电性能，因此无法直接进行电学测试，需要在BiFeO 3、CoFe 2O 4和基板之间增加一层外延氧化物底电极。此时，由外延氧化物底电极直接与BiFeO 3和CoFe 2O 4接触，因此，外延物底电极相当于一层基板，在计算界面结构时，需要计算外延氧化物底电极与BiFeO 3和CoFe 2O 4的界面结构。本实施例外延氧化物底电极以钌酸锶SrRuO 3为例。
右侧为铁酸铋BiFeO 3(简称BFO)与钌酸锶SrRuO 3(简称SRO)的最稳定的界面结构示意图，左侧为铁酸钴CoFe 2O 4(简称CFO)与钌酸锶SrRuO 3的最稳定的界面结构示意图。
分别计算上述两种的界面结合能，其中铁酸铋BiFeO 3与钌酸锶SrRuO 3的界面结合能为-1.81J/m 2，铁酸钴CoFe 2O 4与钌酸锶SrRuO 3的界面结合能为-1.02J/m 2。
铁酸钴CoFe 2O 4/钌酸锶SrRuO 3的界面结合能与铁酸铋BiFeO 3/钌酸锶SrRuO 3的界面结合能差值为0.79>0。因此，可以得到结论：铁酸铋BiFeO 3、铁酸钴CoFe 2O 4与钌酸锶(001)SrRuO 3基板构成的竖直柱状自组装薄膜中，铁酸钴CoFe 2O 4会形成竖直柱镶嵌在铁酸铋BiFeO 3中。
关于上述铁酸钴CoFe 2O 4与铁酸铋BiFeO 3所形成的铁酸钴CoFe 2O 4为纳 米柱材料、铁酸铋BiFeO 3为基体材料、钌酸锶(001)SrRuO 3为外延物底电极的竖直柱状自组装薄膜的制备方法，与上述实施例二的制备方式的方式相同，因此不在赘述。
通过实施例三的方法制备的这种竖直柱状自组长薄膜结构，与单独的铁酸钴CoFe 2O 4或者单独的铁酸铋BiFeO 3形成的两种薄膜相比，能够显著提升铁磁性能。
实施例四
本实施例四以多铁材料铁酸铋BiFeO 3和铁磁材料铁酸钴CoFe 2O 4为薄膜的制备材料、选择(111)方向的钛酸锶SrTiO 3为基板作为例子进行详细论述由于铁酸铋BiFeO 3和CoFe 2O 4没有导电性能，因此无法直接进行电学测试，需要在BiFeO 3、CoFe 2O 4和基板之间增加一层外延氧化物底电极。此时，由外延氧化物底电极直接与BiFeO 3和CoFe 2O 4接触，因此，外延物底电极相当于一层基板，在计算界面结构时，需要计算外延氧化物底电极与BiFeO 3和CoFe 2O 4的界面结构。本实施例外延氧化物底电极以钌酸锶(111)SrRuO 3为例。
左侧为铁酸铋(111)BiFeO 3与钌酸锶(111)SrRuO 3的最稳定的界面结构示意图，右侧为铁酸钴(111)CoFe 2O 4与钌酸锶(111)SrRuO 3的最稳定的界面结构示意图。
分别计算上述两种的界面结合能，其中铁酸铋(111)BiFeO 3与钌酸锶(111)SrRuO 3的界面结合能为-1.59J/m 2，铁酸钴(111)CoFe 2O 4与钌酸锶(111)SrRuO 3的界面结合能为-4.38J/m 2。
铁酸铋(111)BiFeO 3/钌酸锶(111)SrRuO 3的界面结合能与铁酸钴(111)CoFe 2O 4/钌酸锶(111)SrRuO 3的界面结合能差值为2.79>0。因此，铁酸铋BiFeO 3、铁酸钴CoFe 2O 4与钌酸锶(111)SrRuO 3基板构成的竖直柱状自组装薄膜中，铁酸钴CoFe 2O 4会形成竖直柱镶嵌在铁酸铋BiFeO 3中。
关于上述铁酸钴CoFe 2O 4与铁酸铋BiFeO 3所形成的铁酸钴CoFe 2O 4为纳米柱材料、铁酸铋BiFeO 3为基体材料、钌酸锶(111)SrRuO 3为外延物底电 极的竖直柱状自组装薄膜的制备方法，与上述实施例二的制备方式的方式相同，因此不在赘述。
通过本发明实施例四提供的方法所制备竖直柱状自组装薄膜的装置得到的BFO-CFO竖直柱状自组装薄膜能够获得磁电耦合效应(ME Effect)，与单独的铁酸钴CoFe 2O 4或者单独的铁酸铋BiFeO 3形成的两种薄膜相比，能够显著提升铁磁性能，可以应用于电子器件中。
需要说明的是，实施例三和实施例四都是通过选择不同方向的钛酸锶SrTiO 3作为基板，会导致完全不同的界面结合能，使得相同的两种物质长在不同方向的基板上，所形成的竖直柱状自组装结构是截然不同的，进一步验证了通过采用本发明实施例提供的检测柱状自组装薄膜结构的方法能够预先确定所形成的竖直柱状自组装薄膜的结构，可以有选择性的制备柱状自组装薄膜，节省制备材料，提高制备效率。
应当理解的是，本发明的上述具体实施方式仅仅用于示例性说明或解释本发明的原理，而不构成对本发明的限制。因此，在不偏离本发明的精神和范围的情况下所做的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。此外，本发明所附权利要求旨在涵盖落入所附权利要求范围和边界、或者这种范围和边界的等同形式内的全部变化和修改例。

Claims (7)

  1. 一种检测柱状自组装薄膜结构的方法，其特征在于，包括：
    采用第一性原理的方法分别构建材料A和与基板最稳定的界面结构a，以及材料B和与基板最稳定的界面结构b；
    分别计算所述界面结构a的界面结合能(E fA)，以及界面结构b的界面结合能(E fB)；
    计算界面结合能(E fA)与界面结合能(E fB)的差值，若所述差值大于零，则由材料A和材料B所形成的柱状自组装薄膜的结构中，材料A为纳米柱材料，材料B为基体材料；若所述差值小于零，由材料A和材料B所形成的柱状自组装薄膜的结构中，材料B为纳米柱材料，材料A为基体材料。
  2. 根据权利要求1所述的方法，其特征在于，所述界面结合能(E fA)的计算步骤包括：
    采用第一性原理的方法分别计算：A材料形成的薄膜和基板完全弛豫后最稳定时的总能量E A(薄膜/基板)、A材料形成的薄膜完全自由时的总能量E A(薄膜)、基板完全自由时的总能量E(基板)；
    根据公式计算界面结合能(E fA)，其中，公式为：界面结合能(E fA)＝[E A(薄膜/基板)-E A(薄膜)-E(基板)]/界面面积。
  3. 根据权利要求1所述的方法，其特征在于，所述界面结合能(E fB)的计算步骤包括：
    采用第一性原理的方法分别计算：B材料形成的薄膜和基板完全弛豫后最稳定时的总能量E B(薄膜/基板)、B材料形成的薄膜完全自由时的总能量E B(薄膜)、基板完全自由时的总能量E(基板)；
    根据公式计算界面结合能(E fB)，其中，公式为：界面结合能(E fB)＝[E B(薄膜/基板)-E B(薄膜)-E(基板)]/界面面积。
  4. 根据权利要求2或3所述的方法，其特征在于，所述第一性原理的方 法的条件为：采用投影缀加波赝势PAW、电子交换关联泛函PBE中的广义梯度近似GGA和平面波截断能为450eV；其中，采用
    Figure PCTCN2019084013-appb-100001
    修正的四面体方法对第一性原理获得的全部数据进行优化处理，优化过程中K点的取值为3×3×1。
  5. 根据权利要求1所述的方法，其特征在于，所述A材料、B材料和基板为单晶结构。
  6. 一种制备柱状自组装薄膜的方法，其特征在于，包括：
    采用权利要求1-5任一项所述的方法检测自组装薄膜的结构，确定A材料为纳米柱材料、B材料为基体材料；
    采用脉冲激光沉积双靶交替生长系统对所述纳米柱材料连续打击m次后，对所述基体材料连续打击n次，打击的m次和n次构成一个打击循环；
    多次进行循环打击，在基板上生长有预设厚度的薄膜；其中，循环打击过程中控制每个循环在基板上所形成的厚度同时小于所述纳米柱材料和所述基体材料的一个单胞高度；
    持续通入大量氧气，控制所述薄膜的降温速度不超过0.4℃/s，直到所述薄膜冷却至室温。
  7. 根据权利要求6所述的方法，其特征在于，采用脉冲激光沉积双靶交替生长系统对所述纳米柱材料连续打击m次之前，还包括：
    采用脉冲激光沉积系统在所述基板上生长一层厚度为10～50nm的外延氧化物底电极。
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140034132A1 (en) * 2012-08-01 2014-02-06 University Of South Carolina Microfluidic Devices for the Generation of Nano-Vapor Bubbles and Their Methods of Manufacture and Use
CN105084305A (zh) * 2015-06-17 2015-11-25 中国科学院微电子研究所 一种纳米结构及其制备方法
CN106277822A (zh) * 2016-07-28 2017-01-04 李志刚 硅纳米柱状阵列材料及其制备方法
CN107194037A (zh) * 2017-04-25 2017-09-22 江苏大学 一种非对称内嵌结构纳米薄膜热整流器的设计方法
CN109179311A (zh) * 2018-08-28 2019-01-11 湘潭大学 一种检测柱状自组装薄膜结构的方法及其制备方法

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050112505A1 (en) * 2003-11-25 2005-05-26 Huang Wen C. Field-assisted micro- and nano-fabrication method
CN101748489A (zh) * 2009-10-16 2010-06-23 齐齐哈尔大学 低温自组装Bi4-xYxTi3O12铁电薄膜的方法
CN102011190B (zh) * 2010-12-22 2012-06-27 南京工业大学 一种利用纳米晶自组装过程制备纳米结构钛酸锶钡铁电薄膜的方法
WO2016198619A1 (en) * 2015-06-12 2016-12-15 Dev Choudhury Bikash An optical transmission filter
CN105789432B (zh) * 2016-04-17 2018-10-23 重庆科技学院 一种基于铁电薄膜和自组装磁性纳米颗粒结构的微纳米磁电耦合器件

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140034132A1 (en) * 2012-08-01 2014-02-06 University Of South Carolina Microfluidic Devices for the Generation of Nano-Vapor Bubbles and Their Methods of Manufacture and Use
CN105084305A (zh) * 2015-06-17 2015-11-25 中国科学院微电子研究所 一种纳米结构及其制备方法
CN106277822A (zh) * 2016-07-28 2017-01-04 李志刚 硅纳米柱状阵列材料及其制备方法
CN107194037A (zh) * 2017-04-25 2017-09-22 江苏大学 一种非对称内嵌结构纳米薄膜热整流器的设计方法
CN109179311A (zh) * 2018-08-28 2019-01-11 湘潭大学 一种检测柱状自组装薄膜结构的方法及其制备方法

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