A controllable micro-explosion-based hexagonal boron nitride atomic-level manufacturing method and device

Abstract

The present application relates to a kind of hexagonal boron nitride atomic level manufacturing method and device based on controllable micro-explosion, belong to two-dimensional material and atomic level precision manufacturing technical field.The present application uses boron-nitrogen energetic compound as boron-nitrogen-energy integration precursor, under the restraint of array type nanometer limited microcavity, by nanosecond pulse quasi-molecular laser synchronous triggering controllable micro-explosion, combined with boron nitride metasomasis growth template and directional uniform electric field, realize nanosecond boron-nitrogen atom directional self-assembly, prepare high-quality single-layer / few-layer hexagonal boron nitride;And by millisecond laser annealing and high-purity nitrogen gas passivation repair lattice defect.The present application compresses the preparation cycle of single-chip 8 inch wafer hexagonal boron nitride to 10 minutes, and the comprehensive energy consumption is only 1% below traditional CVD process, can accurately control layer number and defect density, 100% compatible with existing semiconductor production line, suitable for the large-scale manufacturing of third-generation semiconductor devices, radio frequency devices, flexible electronics and other fields.

Description

Technical Field

[0001] This invention belongs to the fields of two-dimensional material manufacturing, atomic-level precision manufacturing, and semiconductor device material manufacturing technology. Specifically, it relates to an atomic-level directional preparation method of hexagonal boron nitride based on controllable micro-explosion of energetic precursors, as well as a supporting manufacturing device for realizing this method. It can be directly applied to the large-scale manufacturing of hexagonal boron nitride in the fields of third-generation semiconductor devices, radio frequency devices, flexible electronics, and quantum devices. Background Technology

[0002] Hexagonal boron nitride (h-BN) is a two-dimensional wide-bandgap insulating material with a graphene-like layered structure. It has ultra-high breakdown field strength, ultra-high thermal conductivity, atomically flat surface, excellent chemical stability and high-temperature stability. It is the best matching substrate and isolation layer material for graphene, silicon carbide and two-dimensional semiconductor devices, and is known as "white graphene". It has irreplaceable core application value in the fields of third-generation semiconductors, 5G / 6G radio frequency devices and quantum devices.

[0003] Currently, the mainstream manufacturing technology for hexagonal boron nitride worldwide faces insurmountable industry pain points, specifically as follows:

[0004] Chemical vapor deposition (CVD) is the mainstream process for preparing hexagonal boron nitride at the wafer level worldwide. It requires vapor phase growth at a high temperature of 1000-1200℃ using borane and ammonia as precursors. The growth cycle of a single 8-inch hexagonal boron nitride film can be as long as 6-10 hours, with extremely high energy consumption. In addition, it is difficult to control the number of layers, resulting in many grain boundary defects, poor layer uniformity, and high overall manufacturing costs. Furthermore, borane and ammonia are highly toxic, flammable, and explosive gases, posing high safety risks and significant environmental pressure during the production process.

[0005] Mechanical exfoliation: the only method capable of preparing high-quality monolayer hexagonal boron nitride, but it can only achieve laboratory-level manual serial preparation, with a production capacity far below the requirements for industrial-scale mass production. More than twice as many times, making it completely impossible to scale up for application.

[0006] Liquid phase exfoliation: The mainstream preparation process for industrial-grade hexagonal boron nitride powder. It involves ultrasonically exfoliating bulk boron nitride with strong acid. The resulting nanosheets have high defect density and uneven size, and can only be used as low-end thermally conductive fillers. They cannot meet the high-end application requirements of semiconductor devices. In addition, the production process generates a large amount of acid and alkali waste liquid, causing serious environmental pollution.

[0007] In summary, existing technologies have consistently failed to simultaneously achieve the five core objectives of low temperature and low energy consumption, wafer-level mass production efficiency, atomic-level layer number control, high quality and low defects, and green safety. This has become a major bottleneck restricting the large-scale development and high-end application of the global hexagonal boron nitride industry. Currently, there is no publicly available technological solution worldwide that can resolve all of these pain points. Summary of the Invention

[0008] The purpose of this invention is to overcome the aforementioned deficiencies of the prior art and provide a method and apparatus for atomic-level manufacturing of hexagonal boron nitride based on controllable micro-explosion. This invention breaks through the traditional technical logic of "boron source and nitrogen source separation, high-temperature long-term growth" in the preparation of hexagonal boron nitride. It uses a boron-nitrogen energetic precursor as an integrated carrier of "boron source + nitrogen source + energy source". Through the synergistic effect of nanoscale confinement, boron nitride template anchoring, and synchronous field-controlled orientation technology, it achieves nanosecond-level high-quality directional preparation of hexagonal boron nitride. At the same time, it is 100% compatible with existing 8 / 12-inch semiconductor wafer production lines, completely solving the industry pain points of high energy consumption, low efficiency, high cost, many defects, and high safety and environmental risks of the existing technology.

[0009] The core inventive concept of this invention is as follows: using a boron-nitrogen-energy integrated energetic precursor system, a controllable micro-explosion is synchronously triggered by a nanosecond laser within a wafer-level array-type nano-confined microcavity, simultaneously releasing the high-temperature and high-pressure thermodynamic environment and highly active boron and nitrogen atom raw materials required for the growth of hexagonal boron nitride; combined with a pre-positioned boron nitride growth template and a directional uniform electric field, the directional self-assembly of boron and nitrogen atoms, the growth of hexagonal boron nitride sheets and the formation of the structure are completed within the nanosecond time window of the explosion, realizing the one-step completion of "ignition-nucleation-film formation", completely subverting the traditional long-term high-temperature heating logic of hexagonal boron nitride manufacturing.

[0010] Compared with the prior art, the present invention has the following disruptive and beneficial technical effects: 1. Achieving a breakthrough in production efficiency, completely revolutionizing the industry's production cycle: Compared with the 6-10 hour wafer-level hexagonal boron nitride growth cycle of traditional CVD processes, this invention improves production efficiency by more than 300 times, compressing the hexagonal boron nitride preparation cycle of a single 8-inch wafer to less than 10 minutes, perfectly matching the mass production pace of semiconductor wafer production lines, and completely solving the core pain point of extremely low production efficiency in existing technologies.

[0011] 2. Collapsed energy consumption and manufacturing costs: This invention does not require long-term heating at ultra-high temperatures of 1000℃+, and the overall energy consumption is less than 1% of that of traditional CVD processes; the utilization rate of boron and nitrogen atoms in the energetic precursor is close to 100%, with no raw material waste, and the overall manufacturing cost can be reduced by more than 90%, completely breaking the cost barrier of the hexagonal boron nitride industry.

[0012] 3. Atomic-level precise layer control with near-zero lattice defects: This invention achieves directional self-assembly of boron and nitrogen atoms through the synergistic constraint of boron nitride templates, electric fields, and lasers. It can precisely prepare 1-5 layers of few-layer hexagonal boron nitride or a single layer of hexagonal boron nitride, with a breakdown field strength of [missing information]. Defect density Surface roughness It fully meets the high-end application requirements of semiconductor devices and quantum devices.

[0013] 4. Green and safe, with no environmental or safety risks: The decomposition products of the energetic precursor of this invention are only the target raw materials of boron and nitrogen atoms and harmless nitrogen gas. There are no toxic waste gases, waste liquids, or solid waste emissions, and there is no need to use highly toxic borane or ammonia, which meets the green manufacturing standards. At the same time, the nano-confined micro-explosion is completely confined within the microcavity, with no risk of energy diffusion or runaway, and the production process is safe and controllable.

[0014] 5. 100% compatible with existing semiconductor production lines, enabling rapid mass production: All core process modules of this invention adopt mature mass production technologies from existing semiconductor and panel industries. There is no need to build a new entire industrial chain. Modular upgrades can be directly carried out on existing silicon carbide and silicon-based production lines, and industrialization can be achieved within 3-5 years without any technological generation gap barriers. At the same time, it can share a set of equipment with silicon carbide and graphene preparation processes to achieve "one machine for multiple production" and greatly improve equipment utilization. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with preferred embodiments. All other embodiments obtained by those skilled in the art based on the core concept of this invention without creative effort are within the scope of protection of this invention.

[0016] Unless otherwise specified, the raw materials and equipment used in the specific embodiments of this invention are all commercially available conventional products; the process methods used are all conventional technical methods in the field unless otherwise specified.

[0017] The core equipment used in this embodiment of the invention includes: a 248nm / 193nm nanosecond pulsed excimer laser and a high-vacuum reaction chamber (ultimate vacuum level). It is equipped with a turbomolecular pump group, an inductively coupled plasma (ICP) etching machine, a PECVD thin film deposition system, a high-precision micro-liquid injection system, and a 308nm excimer laser annealing module; the core detection methods include: Raman spectroscopy to test the number of hexagonal boron nitride layers / defects, atomic force microscopy (AFM) to test surface roughness, transmission electron microscopy (TEM) to observe the layer structure, and a breakdown voltage test system to test the breakdown field strength.

[0018] Example 1: Wafer-level preparation of a single-layer hexagonal boron nitride thin film (for semiconductor devices)

[0019] This embodiment is used to prepare an 8-inch monolayer hexagonal boron nitride thin film for silicon carbide power devices and graphene radio frequency devices. The specific steps are as follows: 1. Substrate pretreatment and growth template preparation: An 8-inch 4H-SiC silicon carbide wafer substrate was selected. After polishing and cleaning, an array of nano-confined microcavities was prepared on the wafer surface using photolithography and ICP dry etching. The planar size of a single microcavity is 3μm×3μm and the depth is 1μm. The fill factor of the microcavity array is 95%. The inner wall of the microcavity was modified by plasma boron nitride treatment and used as a directional template for the growth of hexagonal boron nitride. 2. Preparation and Filling of Boron-Nitrogen Integrated Energy Precursor: Using cubane boron-nitrogen complex as the boron-nitrogen energetic precursor and anhydrous tetrahydrofuran as the solvent, a homogeneous energetic precursor solution with a mass concentration of 8% was prepared by stirring in an anhydrous and oxygen-free glove box for 20 min; under a vacuum degree of... Under high vacuum conditions, a micro-volume injection system was used to precisely fill all microcavities with the precursor solution, achieving a filling error of ≤0.1%. A 100nm thick layer was deposited using PECVD technology. A thin film is used to seal the opening of the microcavity; 3. Pre-field control and pre-temperature control: Place the filled wafer substrate on the high-precision heating stage of the vacuum reaction chamber, and evacuate the vacuum reaction chamber to... The substrate was heated to 700°C and held at that temperature under extreme vacuum, while parallel plate electrodes were applied to the upper and lower sides of the substrate. A uniform electric field perpendicular to the substrate surface; 4. Controllable micro-explosion and directional growth of hexagonal boron nitride: A 248nm nanosecond pulsed excimer laser was used for full-area exposure of the substrate, with a laser energy density of [missing information]. The pulse width is 20ns, and the energy uniformity of the entire wafer is ≤0.3%. The laser synchronously triggers nanosecond-level controllable micro-explosions in all precursors in the microcavities. The precursors decompose to generate highly active boron atoms, nitrogen atoms, and nitrogen protective gas, while releasing instantaneous high temperature of 1800K and instantaneous high pressure of 12GPa. Under the synergistic constraints of boron nitride template, uniform electric field and laser polarization, boron atoms and nitrogen atoms complete directional self-assembly in situ in the microcavities to generate a single layer of hexagonal boron nitride that matches the template. 5. In-situ post-processing: After the micro-explosion reaction, the substrate was annealed in milliseconds using a 308nm excimer laser at a peak annealing temperature of 1200℃ for 5ms to repair the lattice defects of hexagonal boron nitride. At the same time, high-purity nitrogen gas with a purity of 99.9999% was introduced to passivate the hexagonal boron nitride at a low temperature of 200℃ for 30s. The nitrogen gas generated by the reaction was removed by a molecular pump system, and the substrate was removed after cooling to room temperature to obtain the target 8-inch monolayer hexagonal boron nitride thin film.

[0020] Performance test results: The hexagonal boron nitride thin film prepared in this embodiment has a pure monolayer structure, and the full width at half maximum (FWHM) of the characteristic peak in the Raman spectrum is [data missing]. No defective peak, breakdown field strength reaches Defect density Surface roughness With a thickness uniformity of ±0.5%, it can be directly used as an insulating substrate and isolation layer for silicon carbide power devices and graphene RF devices; the total time for single-wafer fabrication is less than 8 minutes, and the overall energy consumption is only 0.5% of that of traditional CVD processes.

[0021] Example 2: Preparation of 3D porous hexagonal boron nitride (for thermal conductivity / catalysis)

[0022] This embodiment is used to prepare 3D porous hexagonal boron nitride for use as a thermally conductive filler and catalyst support in power modules for new energy vehicles. The specific steps are as follows: 1. Substrate pretreatment and growth template preparation: A nickel foil substrate was selected, and a three-dimensional mesh-like nano-confined microcavity was prepared on the substrate surface using MEMS technology. The microcavity pore size was 8 μm and the depth was 12 μm. The inner wall of the microcavity was modified with boron nitride. 2. Precursor Preparation and Filling: Using boron azide derivatives as boron-nitrogen energetic precursors and anhydrous n-hexane as solvent, a homogeneous precursor solution with a mass concentration of 12% was prepared. Microcavity filling and... Membrane sealing; 3. Pretreatment: Heat the substrate to 800℃ and apply... A vertical uniform electric field, with the vacuum level maintained at ; 4. Synchronous Micro-Explosion and 3D Structure Forming: A 193nm nanosecond pulsed excimer laser was used to expose the entire substrate, with a laser energy density of [missing information]. With a pulse width of 15ns, it synchronously triggers a controllable micro-explosion in all precursors within the microcavities, completing the in-situ forming of 3D porous hexagonal boron nitride in one step. 5. In-situ post-processing: Lattice defects were repaired by 1300℃ millisecond-level laser annealing, and nitrogen passivation was performed at 220℃ for 30s. After the reaction gas was removed, the substrate was taken out and the nickel foil substrate was removed by acid washing to obtain pure 3D porous hexagonal boron nitride.

[0023] Performance test results: The thermal conductivity of the 3D porous hexagonal boron nitride prepared in this embodiment reaches [value missing]. Specific surface area reaches With a porosity of 82% and a high-temperature stability of over 1200℃, it can be directly used as a thermal conductive filler for power modules in new energy vehicles and a high-temperature catalyst carrier. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly described below. These drawings constitute a part of this specification and are used to further understand the present invention. They are used together with the specific embodiments of the present invention to explain the present invention and do not constitute a limitation thereof.

[0025] Figure 1 is a schematic diagram of the overall structure of the hexagonal boron nitride atomic-level manufacturing apparatus of the present invention;

[0026] Figure 2 is a process flow diagram of the atomic-level manufacturing method of hexagonal boron nitride according to the present invention;

[0027] Figure 3 is a schematic cross-sectional view of the array-type nano-confined microcavity described in this invention;

[0028] Figure 4 is a schematic diagram of the principle of the controllable micro-explosion directional growth of hexagonal boron nitride described in this invention.

[0029] The component names marked in the attached diagram are as follows: 1 - Vacuum reaction chamber system; 2 - Upper electrode; 3 - Lower electrode; 4 - Substrate heating stage; 5 - Conductive growth substrate; 6 - Laser incident window; 7 - Vacuum evacuation port; 8 - Protective gas (nitrogen) inlet; 9 - Electrode terminals; 10 - Array-type nano-confined microcavity; 11 - Nanosecond-level controllable micro-explosion region; 12 - Highly active boron and nitrogen atoms; 13 - Boron nitride growth template; 14 - Precursor filling and sealing system; 15 - Wafer-level laser synchronous triggering system.

Claims

1. A method for atomic-level manufacturing of hexagonal boron nitride based on controllable micro-explosion, characterized in that, Includes the following steps: S1 Substrate pretreatment and growth template preparation: A conductive substrate is selected as the growth substrate, and an array of nano-confined microcavities are prepared on the substrate surface. The inner wall of the nano-confined microcavities is modified with boron nitride to serve as a directional template for the growth of hexagonal boron nitride. S2 Preparation and Filling of Boron-Nitrogen Integrated Energy Precursor: Using boron-nitrogen energetic compounds as the boron source, nitrogen source, and detonation source, dopant elements are added as needed to prepare a homogeneous energetic precursor; under vacuum conditions... In a high vacuum environment, the energetic precursor is precisely filled into the nano-confined microcavity, and the opening of the microcavity is sealed. S3 Pre-field control and pre-temperature control: The filled substrate is placed in a vacuum reaction chamber and heated to a pre-temperature control range of 500-900℃. At the same time, a directional uniform electric field perpendicular to the substrate surface is applied to the upper and lower sides of the substrate. S4 Controllable Micro-Explosion and Directional Growth of Hexagonal Boron Nitride: A nanosecond pulsed excimer laser is used to expose the entire wafer surface of the substrate. The laser synchronously triggers nanosecond-level controllable micro-explosions in all energetic precursors within the nano-confined microcavities. The energetic precursors decompose to generate highly active boron atoms, nitrogen atoms, and nitrogen protective gas, while simultaneously releasing instantaneous high temperatures of 1200-2200K and instantaneous high pressures of 8-20GPa. Under the synergistic constraints of the boron nitride template, uniform electric field, and laser polarization, boron atoms and nitrogen atoms complete directional self-assembly in situ within the microcavities, generating monolayer / few-layer hexagonal boron nitride that matches the template. S5 In-situ Post-processing: After the micro-explosion reaction is completed, the substrate is subjected to millisecond-level laser annealing to repair the lattice defects of hexagonal boron nitride. At the same time, high-purity nitrogen gas is introduced to perform low-temperature passivation treatment on the surface of hexagonal boron nitride. The protective gas generated by the reaction is removed through a vacuum system, and the target hexagonal boron nitride structure is finally obtained.

2. The manufacturing method according to claim 1, characterized in that, The boron-nitrogen energetic compound is one or more of boron azide derivatives, nitrogen heterocyclic boranes, and cubic boron-nitrogen complexes, and the dopant element precursor is a carbon source or silicon source compound, used to prepare C / Si doped functionalized hexagonal boron nitride.

3. The manufacturing method according to claim 2, characterized in that, The homogeneous energetic precursor is an anhydrous and oxygen-free solution, the solvent is anhydrous tetrahydrofuran or anhydrous n-hexane, and the mass concentration of the boron-nitrogen energetic compound is 3%-18%.

4. The manufacturing method according to claim 1, characterized in that, The conductive substrate is one of copper foil, nickel foil, silicon wafer, and silicon carbide wafer. The depth of the nano-confined microcavity is 2nm-40μm, and the planar size of a single microcavity is 10nm-60μm. The array arrangement of the microcavities is completely matched with the structure of the target hexagonal boron nitride device. It is prepared by MEMS photolithography and dry etching process.

5. The manufacturing method according to claim 4, characterized in that, In step S2, a 50-150 nm thick layer is deposited using PECVD technology. The thin film seals the opening of the microcavity, and the error in the amount of precursor filling in a single microcavity is ≤0.1%.

6. The manufacturing method according to claim 1, characterized in that, In step S3, the field strength of the directional uniform electric field is Vacuum degree of the vacuum reaction chamber .

7. The manufacturing method according to claim 1, characterized in that, In step S4, the wavelength of the nanosecond pulsed excimer laser is 193nm or 248nm, and the laser energy density is... The pulse width is 10-100ns, and the energy uniformity of the entire wafer in surface exposure is ≤0.5%.

8. The manufacturing method according to claim 1, characterized in that, In step S4, the instantaneous high temperature of the controllable micro-explosion is maintained for 10-80 ns, and the generated hexagonal boron nitride is 1-5 layers of few-layer hexagonal boron nitride or a single layer of hexagonal boron nitride with a sheet size of 0.5-15 μm.

9. The manufacturing method according to claim 1, characterized in that, In step S5, the peak temperature of laser annealing is 1000-1400℃, the temperature of nitrogen passivation is 150-250℃, the passivation time is 10-60s, and the nitrogen purity is ≥99.9999%.

10. The manufacturing method according to any one of claims 1-9, characterized in that, The prepared hexagonal boron nitride has a breakdown field strength ≥8MV / cm and a defect density of 0.5%. Surface roughness .

11. An atomic-level manufacturing apparatus for hexagonal boron nitride according to any one of claims 1-10, characterized in that, include: The high-vacuum reaction chamber system is equipped with a high-precision substrate heating stage, a molecular pump pumping unit, and multiple gas pathways, achieving an ultimate vacuum level. ; The precursor filling and sealing system includes a high-vacuum micro-injection unit and a nano-scale thin-film sealing unit, which are used to complete the precise filling and micro-cavity sealing of energetic precursors in a high-vacuum environment. The electric field control system, including parallel plate electrodes and a high-precision high-voltage power supply, can output electric field strength. Adjustable vertical uniform electric field; The wafer-level laser synchronous triggering system includes a nanosecond pulsed excimer laser with wavelengths of 193nm / 248nm and pulse widths of 10-100ns, as well as a surface exposure homogenizing optical path, which can achieve uniform exposure of the entire 8 / 12-inch wafer with energy uniformity ≤0.5%. The in-situ post-processing system, including a millisecond-level laser annealing module and a nitrogen atmosphere control unit, is used for lattice repair and surface passivation of hexagonal boron nitride structures, and can achieve millisecond-level laser annealing at 1000-1400℃ and nitrogen passivation treatment at 150-250℃. The closed-loop measurement and control system is electrically connected to the above systems and is used for real-time monitoring and closed-loop control of vacuum degree, temperature, electric field intensity, laser parameters and reaction process.

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