Method for producing boron nitride thin film and boron nitride thin film

Abstract

To provide a method for manufacturing a boron nitride thin film, operated at low temperature and capable of reducing the risk of thermal damage to a substrate and energy consumption, and the boron nitride film.SOLUTION: A method for manufacturing a boron nitride thin film comprises steps of: supplying a precursor including a boron atom and a nitrogen atom to an energy control device; forming the excitation state of the precursor in the energy control device; and forming a material layer including boron nitride on a substrate. The main feature of the method is the use of the energy control device including a first electromagnetic wave source for radiating an electromagnetic wave having a specific wavelength range; and the method comprises some additional steps for further promoting the formation of the boron nitride thin film.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a thin film and the thin film itself, and more particularly to a method for producing a boron nitride thin film and a boron nitride thin film.The present invention belongs to the field of thin films, and in particular to a method for producing a boron nitride thin film. [Background technology]

[0002] Boron nitride thin films have attracted attention in a wide range of fields due to their unique mechanical, thermal, chemical, and electrical properties. These properties make them particularly suitable for use in high-temperature and high-pressure environments, and they are used in applications such as cutting tools, electronic devices, and protective coatings. Boron nitride thin films are typically synthesized using chemical vapor deposition (CVD) or physical vapor deposition (PVD) techniques, using precursors such as boron ureas and aminoboranes.

[0003] However, synthesizing high-quality BN thin films remains challenging due to the difficulty in controlling the stoichiometry, phase, and microstructure of the films. For example, conventional chemical vapor deposition techniques require high-temperature environments, which can cause thermal damage to the substrate and increase energy consumption. On the other hand, physical vapor deposition techniques can be performed at low temperatures, but they have limited control over the stoichiometry and phase of the films. Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, although boron nitride thin films have many excellent properties, there are still significant issues in their manufacturing process, making them difficult to put into practical use. Therefore, addressing these issues is a topic of great interest to those skilled in the art. The present invention aims to solve the above-mentioned issues, and provides a method for manufacturing a boron nitride thin film and a boron nitride thin film itself. [Means for solving the problem]

[0005] In accordance with the objectives of the present invention and other objectives, the present invention provides a method for producing a boron nitride thin film, comprising the steps of: first, supplying a precursor containing boron and nitrogen atoms to an energy control device; second, forming an excited state of the precursor in the energy control device; this excited state containing boron and nitrogen atoms, some or all of whose ligands are in a bond-breaking state; and then forming a material layer containing boron nitride on a substrate. During this process, the energy control device includes a first electromagnetic wave source that emits electromagnetic waves within a specific wavelength range.

[0006] In certain embodiments, the precursor is selected from compounds having a 1:1 atomic ratio of boron to nitrogen. Further, the precursor may be borazine (B3H6N3), tris(dimethylamino)borane (TDMAB, CH3H 12 The boron-nitrogen ion is selected from compounds including tetramethylammonium borane, boron urea, aminoborane (BHN), and tris(ethylmethylamino)borane (TEMAB), all of which have a 1:1 atomic ratio of boron to nitrogen. Some embodiments also include forming a substrate bias to reduce particle deposition on the surface of the substrate. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a flow chart illustrating an embodiment of a method for forming a boron nitride layer on a substrate according to the present invention. [Figure 2A] 1 is a diagram illustrating an embodiment of an energy control device of the present invention. [Figure 2B] FIG. 10 illustrates another embodiment of the energy control device of the present invention. [Figure 3] FIG. 1 is a diagram showing a substrate on which a boron nitride thin film is formed. [Figure 4] FIG. 2 is a schematic diagram showing the inside of a reaction chamber. DETAILED DESCRIPTION OF THE INVENTION

[0008] Referring to the work steps shown in FIG. 1, the present invention provides a method for fabricating a boron nitride thin film on a substrate. The method of the present invention begins with supplying a precursor containing boron and nitrogen atoms to an energy control device, as shown in step S110. Here, the precursor is selected from compounds having a boron to nitrogen atomic ratio of 1:1. Examples of such compounds include borazine (a boron-nitrogen cyclic compound, B3H6N3), trimethylamine borane (C3H 12 The organic solvent may include one or more selected from the group consisting of tetramethylammonium borohydride (BN), tetramethylammonium borohydride, boron nitride, ammonia borane (BHN), and triethylmethylamine borane (TEMAB).

[0009] Borazine is a colorless liquid at room temperature and is known to be used as a precursor for preparing boron nitride thin films due to its high thermal stability. Tris(dimethylamino)borane is known for its high reactivity and volatility, making it suitable for chemical vapor deposition processes. Tetramethylammonium borohydride is an air-stable compound and can be used as a single-source precursor for preparing boron nitride thin films. Boron urea is stable under normal conditions and can be used as a precursor for synthesizing boron nitride nanotubes. Aminoborane is a solid at room temperature and can be used as a precursor for synthesizing boron nitride nanotubes and nanosheets. Tris(ethylmethylamino)borane is a stable compound under normal conditions and can be used as a precursor for synthesizing boron nitride thin films. In the present invention, these compounds can be used alone or in combination.

[0010] An embodiment of the energy control device of the present invention will be described in detail with reference to FIGS. 1 and 2A. The energy control device 100 includes a power source 101, a first electromagnetic wave source 102, and a propagation device 103 that emits electromagnetic waves, such as a waveguide or antenna. The power source 101 supplies energy to the first electromagnetic wave source 102 to generate electromagnetic waves. The first electromagnetic wave source 102 is a device that generates electromagnetic waves at a specified wavelength and energy level, and the propagation device 103 directs the electromagnetic waves toward the precursor. The energy control device 100 also includes a control system 104 that adjusts the wavelength and energy of the electromagnetic waves. In this embodiment, the control system 104 includes a microprocessor 104a or other type of controller and a sensor 104b that monitors the wavelength and energy of the electromagnetic waves. The microprocessor 104a adjusts the operation of the first electromagnetic wave source 102 based on the readings of the sensor 104b to maintain the electromagnetic waves at the desired wavelength and energy level. The energy control device 100 also includes a cooling system 105 and a safety system 106. A cooling system 105 is provided to cool the components of the energy control device 100 and prevent overheating. A safety system 106 is a device to ensure the safety of the energy control device 100 during operation and automatically shuts down the device if abnormal operation is detected. Furthermore, the energy control device 100 is provided with channels (not shown) for introducing and discharging precursors.

[0011] In one embodiment of the method, precursors are introduced into the energy control device 100 under specific temperature conditions. In this embodiment, the temperature is maintained in the range of 25°C to 400°C. The precursors are introduced into the energy control device 100 using an inert carrier gas, such as argon, helium, nitrogen, or a combination of these gases. The inert gas is selected based on its ability to keep the precursor stable and its compatibility with the precursor and the energy control device 100. During this fabrication process, the flow rate of the inert carrier gas can be adjusted to optimize the formation of excited states in the precursor. A high flow rate is used to rapidly introduce the precursor into the energy control device, while a low flow rate is used to ensure sufficient interaction between the precursor and the electromagnetic wave. The flow rate can also be adjusted based on changes in temperature and pressure within the energy control device. This allows for dynamic control of the process and the formation of high-quality boron nitride thin films on substrates.

[0012] In one embodiment, the molar fraction of the precursor containing boron atoms and nitrogen atoms in the inert carrier gas is 0.5% to 10%. The flow rate of the inert carrier gas entering the energy control device 100 is set to 20 to 40 sccm (standard cubic centimeters per minute), the vapor pressure within the energy control device 100 is set to 20 to 60 torr, and the average residence time of the inert carrier gas is 10 to 100 seconds.

[0013] Continuing with reference to FIGS. 1 and 2A, in step S120, the precursor is brought to a high-energy state, i.e., an "excited state," via the energy control device 100. This excited state includes cases where the boron and nitrogen atoms are in excited states and cases where some or all of the ligands are in bond-scission states. In one embodiment, the first electromagnetic wave source 102 of the energy control device 100 emits controlled electromagnetic waves with a wavelength in the range of 180 nm to 500 nm and an energy in the range of 100 W to 600 W. In another specific embodiment, in addition to the components shown in FIG. 2A, the energy control device 100' includes a second electromagnetic wave source 107, as shown in FIG. 2B. The wavelength of the second electromagnetic wave source 107 is in the range of 0.5 nm to 180 nm and an output power in the range of 100 W to 600 W. The wavelength of the electromagnetic waves from the second electromagnetic wave source 107 is shorter than that of the first electromagnetic wave source 102. Shorter wavelengths correspond to higher energy photons. These higher energy photons can more effectively excite the precursors and more efficiently form excited states. By adjusting the first electromagnetic wave source 102 and the second electromagnetic wave source 107, the formation of the excited states of the precursors can be optimized.

[0014] Referring to Figures 1 and 3, Figure 3 illustrates a boron nitride thin film formed on a substrate. In step S130, an excited state precursor is introduced to at least one surface of the substrate 20. The key to this step is that the precursor is in an excited state. In this excited state precursor, the boron and nitrogen atoms, or some or all of the ligands on these atoms, are in a bond-breaking state. This bond-breaking state means that the boron and nitrogen atoms are excited and ready to chemically react with other atoms or molecules. This state is achieved by exposing the precursor to specific energy conditions provided by an energy control device.

[0015] Once the excited precursors are introduced to the substrate 20, the excited boron and nitrogen atoms begin to form a new material layer 21 on the substrate, as shown in step S140. This new material layer 21 comprises boron nitride, i.e., a boron nitride thin film. The specific properties of the formed boron nitride thin film are determined by the arrangement of the boron and nitrogen atoms on the substrate. In summary, step S130 primarily involves introducing the excited precursors to the substrate, forming a material layer containing boron nitride on the substrate. The temperature of the substrate 20 during this process is maintained at approximately 400°C or below.

[0016] The material layer 21 may include hexagonal boron nitride (h-BN), cubic boron nitride (c-BN), or amorphous boron nitride (a-BN). The different crystalline structures of boron nitride in the material layer, e.g., h-BN, c-BN, or a-BN, result from different atomic arrangements of boron and nitrogen atoms in the material layer. These different crystalline structures result in different physical and chemical properties that may be advantageous for various applications. For example, h-BN has a layered structure similar to graphite and is highly useful as a lubricant. On the other hand, c-BN has a structure similar to diamond and is extremely hard, making it highly useful as a cutting tool. Amorphous boron nitride has a unique disordered structure, resulting in unique physical and chemical properties not found in materials with an ordered structure.

[0017] Therefore, amorphous boron nitride may exhibit superior performance in certain specialized applications, such as in high-temperature or high-pressure environments, or situations requiring high wear and corrosion resistance. Furthermore, the disordered structure of amorphous boron nitride provides excellent thermal and chemical stability, allowing it to maintain its structure and performance even at high temperatures or in harsh chemical environments. For this reason, amorphous boron nitride is widely used in a variety of industrial applications, including high-performance lubricants, wear-resistant materials, and corrosion-resistant coatings.

[0018] In this embodiment, the material of the substrate 20 is selected from metals, metal alloys, ceramics, polymers, or combinations thereof. Specifically, the material of the metal substrate is selected from aluminum, copper, steel, or combinations thereof. The material of the metal alloy substrate is selected from stainless steel, brass, bronze, or combinations thereof. The material of the ceramic substrate is selected from alumina, zirconia, silicon carbide, or combinations thereof. The material of the polymer substrate is selected from polyethylene, polypropylene, polystyrene, or combinations thereof. The selection of the substrate material is determined by various factors, such as the required properties of the boron nitride thin film, the application of the product, and the conditions under which the product will be used.

[0019] For example, when selecting a substrate material that provides high mechanical strength and excellent wear resistance, those skilled in the art may choose to use stainless steel or alumina as the substrate material. This allows the formed boron nitride layer to be strongly bonded to the substrate and maintain its performance for a long period of time even under harsh usage conditions. On the other hand, when excellent chemical stability in a specific environment is required, zirconia or silicon carbide may be selected as the substrate material. This allows the formed boron nitride layer to not deteriorate even in a chemically harsh environment and to provide stable performance.

[0020] It is worth noting that the substrate 20 may be treated or coated prior to depositing the boron nitride thin film to enhance adhesion between the material layer 21 and the substrate 20. For example, the substrate may be cleaned, roughened, or coated with a primer or adhesion promoter. Additionally, in one embodiment, an electric field, referred to as a substrate bias, may be applied to the substrate 20 to reduce the deposition of charged particles on the surface of the substrate 20. The substrate bias may be either a positive bias or a negative bias depending on the polarity of the charged particles. For example, a positive bias is established if the charged particles are primarily positively charged, and conversely, a negative bias is established if the charged particles are primarily negatively charged.

[0021] The purpose of setting the substrate bias is to improve the quality of the deposited boron nitride film by eliminating charged particles that may interfere with the deposition process. When the substrate is biased, the electric field affects the movement of charged particles, making it more difficult for these particles to deposit directly on the substrate surface. This reduces the random deposition of charged particles on the substrate surface, resulting in a smoother, more uniform material layer 21. Therefore, setting the substrate bias can improve the quality of the boron nitride thin film.

[0022] See also FIG. 4, which shows a schematic diagram of the interior of a reaction chamber. In one embodiment, step S130 is performed in a reaction chamber 200 equipped with a plasma source 210. This design aims to increase the rate of boron nitride formation. The plasma source 210 in the reaction chamber 200 plays a key role in this process. The main function of the plasma source 210 is to generate plasma, which is a gas that contains an equal number of positive and negative charges in an electrically unbalanced state. In this state, the gas atoms or molecules are ionized by the energy of the plasma source 210, forming charged particles. These charged particles have high energy and can undergo further chemical reactions with the precursor.

[0023] During this chemical reaction, the charged particles combine with boron and nitrogen atoms in the precursor to form boron nitride. This chemical reaction takes place within the reaction chamber 200 and under the influence of the plasma source 210. Furthermore, the plasma source 210 can take various forms, such as direct current (DC) plasma, radio frequency (RF) plasma, electron cyclotron resonance (ECR) plasma, or a combination of these. Each plasma source type has specific operating conditions and advantages. For example, DC plasma sources are the most common type and use direct current voltage to generate plasma. RF plasma sources use radio frequency voltage to generate plasma, operate at low pressures, and can generate high plasma densities. ECR plasma sources use magnetic fields to generate plasma, operate at very low pressures, and can generate very high plasma densities.

[0024] In this embodiment, the energy output of the plasma source 210 is set to exceed 300 W. This energy setting allows the plasma source to effectively generate plasma and provide sufficient energy to ionize gas atoms or molecules to form charged particles. This energy setting can also be adjusted according to the needs of a particular application. Furthermore, the plasma is composed of at least one gas selected from argon, helium, nitrogen, hydrogen, ammonia, or a combination thereof. These gases are selected for their ability to effectively generate plasma and their compatibility with the precursors and reaction chamber. For example, argon and helium are the most commonly used plasma gases because they have high ionization energy and generate high-density plasma. Nitrogen and hydrogen can be used when specific chemical reactions are required within the plasma. Ammonia can be used when chemical reactions involving nitrogen are required within the plasma.

[0025] In summary, the method for fabricating boron nitride thin films of the present invention offers several important advantages over existing methods for depositing boron nitride thin films. First, the method for fabricating boron nitride thin films operates at low temperatures, significantly reducing the risk of thermal damage to the substrate and reducing energy consumption. This low-temperature fabrication method not only increases efficiency but also makes it environmentally friendly. Furthermore, the method for fabricating boron nitride thin films includes several additional options to further enhance the formation of boron nitride thin films. For example, applying a substrate bias can reduce the deposition of charged particles on the substrate surface and improve the quality of the boron nitride layer. Furthermore, including a plasma source in the reaction chamber can increase the boron nitride formation rate and improve production efficiency. These optional steps make the method for fabricating boron nitride thin films more flexible and can be tailored to specific needs.

[0026] As described above, the present invention has been disclosed based on the preferred embodiments, but these are not intended to limit the present invention. Those skilled in the art can make appropriate changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. (a) providing a precursor comprising boron atoms and nitrogen atoms to an energy control device; (b) forming an excited state of the precursor in the energy control device; (c) forming a layer of material comprising boron nitride on the substrate; the excited state of the precursor comprises a boron atom and a nitrogen atom, or a boron ligand and a nitrogen ligand in a bond dissociation state; the energy control device includes, in this order, a first electromagnetic wave source that emits electromagnetic waves having a wavelength of 180 nm or more and 500 nm or less and a power of 100 W or more and 600 W or less, and a second electromagnetic wave source that emits electromagnetic waves having a wavelength of 0.5 nm or more and 180 nm or less and a power of 100 W or more and 600 W or less; The precursor is delivered to the energy control device using an inert carrier gas; The average residence time of the inert carrier gas in the energy control device is 10 seconds or more and 100 seconds or less, The pressure inside the energy control device is 20 torr or more and 60 torr or less, A method for producing a boron nitride thin film, wherein in the step (c), the temperature of the substrate is maintained at 400° C. or less.

2. 2. The method for producing a boron nitride thin film according to claim 1, wherein the precursor is selected from compounds having an atomic ratio of boron to nitrogen of 1:

1.

3. 3. The method for producing a boron nitride thin film according to claim 2, wherein the precursor contains one or more precursors selected from the group consisting of borazine, trimethylamine borane, tetramethylammonium borane, boron nitride, ammonia borane, and tris(ethylmethylamino)borane, each of which has an atomic ratio of boron to nitrogen of 1:

1.

4. 2. The method for producing a boron nitride thin film according to claim 1, wherein the material constituting the substrate includes at least one selected from the group consisting of metals, metal alloys, ceramics, polymers, and combinations thereof.

5. 2. The method for producing a boron nitride thin film according to claim 1, wherein the material layer comprises hexagonal boron nitride, cubic boron nitride, or amorphous boron nitride.

6. 2. The method for producing a boron nitride thin film according to claim 1, wherein in step (a), the precursor is supplied to the energy control device at a temperature of 25°C to 400°C.

7. 2. The method for producing a boron nitride thin film according to claim 1, wherein the inert carrier gas is one or more selected from the group consisting of argon, helium, nitrogen, and combinations thereof.

8. 2. The method for producing a boron nitride thin film according to claim 1, wherein the molar concentration of the precursor in the inert carrier gas is 0.5% or more and 10% or less.

9. 2. The method for producing a boron nitride thin film according to claim 1, wherein the flow rate of said inert carrier gas to said energy control device is 20 sccm or more and 40 sccm or less.

10. 2. The method for producing a boron nitride thin film according to claim 1, wherein step (c) further comprises forming a substrate bias on the surface of the substrate to reduce particle deposition on the surface of the substrate.

11. 2. The method for producing a boron nitride thin film according to claim 1, further comprising providing a reaction chamber including a plasma source in step (c) to increase the rate at which the boron nitride is formed.

12. 12. The method for producing a boron nitride thin film according to claim 11, wherein the plasma source comprises at least one selected from the group consisting of direct current plasma, radio frequency plasma, electron cyclotron resonance plasma, and combinations thereof, and the energy of the plasma emitted from the plasma source exceeds 300 W.

13. 13. The method for producing a boron nitride thin film according to claim 12, wherein the plasma contains at least one gas selected from argon, helium, nitrogen, hydrogen, ammonia, or a combination thereof.

Images