A microchannel diamond film device and its preparation method

Abstract

The present invention provides a microchannel diamond film device and its preparation method, relating to the field of heat dissipation device manufacturing technology. The device comprises a substrate provided with a serpentine groove, the depth of which is greater than the width. The device also includes a first diamond film attached to the inner wall of the serpentine groove and a second diamond film covering the upper surface of the substrate. The first and second diamond films are connected to form a serpentine microchannel within the substrate. The serpentine microchannel includes an inlet and an outlet for the flow of cooling medium. The present invention aims to design a microchannel diamond film device to improve the cooling efficiency of highly integrated, high-power, and miniaturized electronic products.

Description

Technical Field

[0001] The present invention relates to the technical field of heat dissipation device manufacturing, and in particular to a microchannel diamond film device and a preparation method thereof. Background Art

[0002] With the development of power devices, more and more electronic products are developing towards miniaturization, high performance and high power. As the integration of electronic products continues to increase and the power continues to increase, the heat is more concentrated and the heat flux density continues to increase. The average heat flux density of electronic devices / systems will reach 500W / cm 2 The heat flux density at a local location in the package can even reach 1000W / cm 2 The heat flux density of traditional air cooling, thermal grease cooling, etc. is only 1W / cm 2 The heat flux density of traditional liquid cooling does not exceed 200W / cm 2 In order to ensure the reliable operation of electronic devices, especially the heat dissipation of high-performance and highly integrated microsystems such as CPUs and GPUs, it is particularly important.

[0003] There is currently no effective technical solution to the above problems. Summary of the Invention

[0004] The present invention aims to provide a microchannel diamond film device and a preparation method thereof, and aims to design a microchannel diamond film device to improve the cooling efficiency of highly integrated, high-power, miniaturized electronic products.

[0005] In a first aspect, the present invention provides a microchannel diamond film device, comprising a substrate, wherein the substrate is provided with a winding groove, the depth of the winding groove being greater than the width; the microchannel diamond film device also includes a first diamond film attached to the inner wall of the winding groove and a second diamond film covering the upper surface of the substrate, the first diamond film and the second diamond film are connected as a whole to enclose a winding microchannel located inside the substrate, and the winding microchannel includes an inlet and an outlet for a cooling medium to enter and exit.

[0006] The microchannel diamond film device provided by the present invention includes a winding microchannel coated with a diamond film, which has the advantages of compact structure and strong heat dissipation capability. The heat dissipation speed is more than 20 times that of traditional heat dissipation devices, effectively improving the cooling efficiency of highly integrated, high-power, and miniaturized electronic products.

[0007] In a second aspect, the present invention provides a method for preparing the above-mentioned microchannel diamond film device, comprising the following steps:

[0008] S1. Processing a winding groove on the substrate;

[0009] S2. Cleaning the processed substrate;

[0010] S3. The cleaned substrate is placed in a mixture of diamond nanocrystal powder and anhydrous ethanol and ultrasonically treated to deposit diamond seeds on the inner wall of the winding groove;

[0011] S4. The substrate is mounted on a rotating platform and an airflow with diamond powder is controlled to spray the airflow at a specified tilt angle toward the upper surface of the substrate to achieve sandblasting seeding treatment on the upper surface of the substrate;

[0012] S5. Place the substrate in an MPCVD system for primary growth, and after the primary growth continues for a specified period of time, perform secondary growth to obtain a microchannel diamond film device with a winding microchannel; the primary growth is used to form a first diamond film of a certain thickness on the inner wall of the winding groove; the secondary growth is used to automatically close the notch of the winding groove and form a second diamond film of a certain thickness on the upper surface of the substrate.

[0013] As can be seen from the above, the microchannel diamond film device provided by the present invention features winding grooves with a high aspect ratio machined within the substrate. These grooves possess a large specific surface area and excellent microscale heat transfer efficiency, effectively enhancing heat transfer capacity. The winding groove design provides excellent heat dissipation uniformity, effectively improving the cooling efficiency of highly integrated, high-power, and miniaturized electronic products.

[0014] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the embodiments of the present invention. The purposes and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the structure of a substrate provided with a winding groove in an embodiment of the present invention.

[0016] Figure 2 A cross-sectional view of a microchannel diamond film device provided in an embodiment of the present invention.

[0017] Figure 3 A flow chart of the preparation method provided in an embodiment of the present invention.

[0018] Description of labels:

[0019] 100, substrate; 110, winding groove; 200, first diamond film; 300, second diamond film. DETAILED DESCRIPTION

[0020] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0022] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections, or mutual communication; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0023] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0024] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0026] It should be noted that similar numbers and letters represent similar items in the following figures, so once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In addition, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined. At the same time, in the description of the present invention, the terms "first", "second", etc. are only used to distinguish descriptions and are not to be understood as indicating or implying relative importance.

[0027] Reference Attachment Figure 1 and attached Figure 2The present invention provides a microchannel diamond film device, comprising a substrate 100, wherein the substrate 100 is provided with a winding groove 110, wherein the depth of the winding groove 110 is greater than the width; the microchannel diamond film device further comprises a first diamond film 200 attached to the inner wall of the winding groove 110 and a second diamond film 300 covering the upper surface of the substrate 100, wherein the first diamond film 200 and the second diamond film 300 are connected as a whole to form a winding microchannel located within the substrate 100, wherein the winding microchannel includes an inlet and an outlet for a cooling medium to enter and exit; the winding groove 110 has a large specific surface area and excellent microscale heat transfer efficiency, which can effectively improve the heat transfer capacity; the winding design of the winding groove 110 has excellent heat dissipation uniformity.

[0028] The substrate refers to the device's supporting structure, used to support the heat-generating device and serve as the starting point for heat transfer. It can be made of materials with good thermal conductivity, such as metal, ceramic, or composite materials. Its primary purpose is to provide structural support and conduct heat to the heat dissipation structure. A serpentine groove refers to a pre-formed recessed structure with a specific shape (e.g., serpentine, vortex, spiral, etc.) on the substrate. This can be achieved through machining, etching, or molding. Its primary purpose is to define the microchannel path and provide internal surface area. A serpentine groove with a depth greater than its width means that the groove has a high aspect ratio, primarily to provide a larger internal surface area within a limited planar area and influence the flow characteristics of the fluid within it. The first diamond film refers to the diamond layer attached to the inner wall of the serpentine groove. It can be grown using methods such as chemical vapor deposition. Its primary purpose is to provide a channel wall with high thermal conductivity. The second diamond film refers to the diamond layer covering the upper surface of the substrate. It can be grown using methods such as chemical vapor deposition. Its primary purpose is to seal the serpentine groove and form a complete microchannel structure. The first and second diamond films are joined as one, forming a continuous structure during the growth process. This ensures the microchannel's tightness and creates a complete heat transfer path. The serpentine microchannel, formed by the substrate, the first and second diamond films, is a closed fluid channel within the substrate, guiding the flow of cooling media and enabling heat exchange. The inlet and outlet ports connect the serpentine microchannel to the external fluid circuit, enabling the circulation of cooling media.

[0029] The core innovation of this application lies in that by combining a diamond film with high thermal conductivity with a winding microchannel structure with a high aspect ratio, an efficient heat transfer path is constructed inside the substrate, which significantly improves the heat dissipation capacity and improves the heat dissipation uniformity.

[0030] Specifically, when the device generates heat during operation, the heat is first conducted through the substrate to the diamond film attached to it. Due to the extremely high thermal conductivity of diamond, heat can be rapidly conducted along the first and second diamond films. The winding microchannel located within the substrate has an inner wall formed by the first diamond film and a top wall covered by the second diamond film, the two of which are connected to form a closed structure. The cooling medium enters the winding microchannel through the inlet and flows along the winding path, exchanging heat with the inner wall of the diamond channel with high thermal conductivity. The high aspect ratio design of the winding groove provides a large heat exchange surface area, increasing the contact area between the cooling medium and the diamond film. The winding path design allows the cooling medium to flow over a longer distance and helps to achieve uniform flow rate and temperature distribution throughout the heat dissipation area. Heat is transferred from the diamond film to the flowing cooling medium, which is discharged through the outlet after the cooling medium temperature rises, removing the heat. The entire process achieves rapid and effective heat removal from the substrate through the synergistic effect of the efficient thermal conductivity of diamond and the efficient heat exchange of the microchannel structure.

[0031] As a preferred embodiment, the solution of the present application is specifically implemented as follows: an aluminum nitride ceramic material can be used as a substrate (for example, with specifications of 15 mm in length, 12 mm in width, and 1.5 mm in thickness), and a winding groove with a high aspect ratio (for example, a depth of 1.5 mm and a width of 0.3 mm) can be processed on the substrate through a deep reactive ion etching process. Subsequently, the processed substrate is cleaned to remove surface residues. Next, a first diamond film is first grown on the inner wall of the winding groove through a chemical vapor deposition method. The film is tightly adhered to the surface of the groove. Then, a second diamond film is continued to grow on the upper surface of the substrate. During the growth process, the second film gradually covers and closes the notch of the winding groove and connects with the first diamond film in the groove to form a continuous integral structure. Finally, a closed winding microchannel composed of a diamond film is formed inside the substrate. The microchannel has an inlet and an outlet for the entry and exit of a cooling medium.

[0032] Through the above-mentioned solution, this application provides a microchannel diamond film device that leverages the high thermal conductivity of diamond and the efficient heat transfer characteristics of the winding microchannel structure to significantly enhance the device's heat dissipation capabilities. The winding path design and high aspect ratio structure increase the heat transfer surface area and optimize fluid distribution, thereby achieving rapid heat conduction and uniform heat dispersion. This effectively addresses the issue of insufficient heat dissipation in high-performance, highly integrated microsystems and ensures reliable device operation.

[0033] In some embodiments, the substrate 100 is made of graphite, copper, aluminum, silicon, ceramic, or aluminum nitride.

[0034] Reference Attachment Figure 3The present invention provides a method for preparing the microchannel diamond film device in the above embodiment, comprising the following steps:

[0035] S1. Processing a winding groove on the substrate;

[0036] S2. Cleaning the processed substrate;

[0037] S3. Place the cleaned substrate in a mixture of diamond nanocrystal powder and anhydrous ethanol and treat it with ultrasound to deposit diamond seeds on the inner wall of the serpentine groove. Although the entire substrate is placed in the beaker, due to the characteristics of the ultrasound treatment, the diamond nanocrystal powder will preferentially deposit inside the serpentine groove. This is because the microstructure inside the serpentine groove (such as the high aspect ratio and surface roughness) is more likely to capture nanoparticles, while the flat surface of the substrate has less deposition. In addition, the subsequent inclined sandblasting treatment will further strengthen the seed distribution on the substrate surface, thereby achieving differentiated seeding inside and outside.

[0038] S4. Install the substrate on a rotating platform, and control the airflow with diamond powder to spray toward the upper surface of the substrate at a specified tilt angle to achieve sandblasting seeding treatment on the upper surface of the substrate. The upper surface of the substrate is mechanically sandblasted and seeded. This process strengthens the surface roughness of the substrate and promotes the physical embedding of diamond particles, thereby increasing the initial nucleation density. Use a rotating substrate with a tilt angle to spray diamond powder, enhance the physical embedding effect of the particle surface, form a high-density seed distribution, and accelerate the lateral expansion of the surface diamond film. The tilt angle (such as 18°) can make the diamond powder more effectively impact the surface of the substrate. The surface is smooth, especially the notch area of ​​the winding groove, to avoid direct vertical impact of particles, which may cause uneven embedding of particles inside the winding groove. Compared with horizontal sandblasting, horizontal sandblasting may cause the particle distribution on the upper surface of the substrate to be too uniform, making it difficult to perform differentiated treatment on the notch and upper surface. However, inclined sandblasting can optimize the physical embedding effect of particles by adjusting the angle, which is more suitable for the seeding needs of complex microstructures. In response to the complexity of the microstructure, ultrasonic seeding and inclined sandblasting are used inside and outside the channel for the first time to achieve directional differentiated seeding. This strategy significantly improves the nucleation uniformity and rate matching between the inner wall and the upper surface of the channel.

[0039] S5. Place the substrate in an MPCVD system for primary growth, and after the primary growth lasts for a specified period of time, perform secondary growth to obtain a microchannel diamond film device with a winding microchannel; the primary growth is used to form a first diamond film of a certain thickness on the inner wall of the winding groove; the secondary growth is used to automatically close the notch of the winding groove and form a second diamond film of a certain thickness on the upper surface of the substrate; since the nucleation and growth rates in the upper surface area are much higher than those inside the channel, the surface film layer gradually expands to the channel mouth (i.e., the notch) during the growth process, and finally realizes automatic closed film formation, forming a three-dimensional diamond composite structure with a complete structure and continuous interface.

[0040] Specifically, in the above method, steps S3 and S4 are the key to achieving differentiated seeding on the inner and outer surfaces of complex microstructures.

[0041] Step S3 uses ultrasonic treatment, leveraging the cavitation effect of ultrasound and liquid flow to effectively transport and evenly deposit diamond nanocrystalline powder within the high-aspect-ratio, winding grooves. Nanocrystalline powder serves as nucleation sites for diamond growth, and its uniform deposition on the inner wall is essential for ensuring the uniformity and density of the subsequent internal film.

[0042] Step S4 uses a mechanical sandblasting seeding method. By rotating the substrate and controlling the tilt angle, the roughness of the substrate's upper surface can be effectively enhanced, promoting the physical embedding of diamond powder, thereby significantly increasing the initial nucleation density on the upper surface. The design of the tilt angle can optimize the impact effect of the particles, making them more effectively embedded in the upper surface, especially the notch area, while avoiding damage or uneven effects on the seeded crystals inside the groove, achieving differentiation and synergy with internal ultrasonic seeding. This internal and external differentiated seeding strategy is an important means to solve the internal and external nucleation uniformity and rate matching of complex microstructures.

[0043] Step S5 employs a staged growth strategy. The primary growth strategy is to form a first diamond film of a certain thickness on the inner walls of the serpentine groove. Secondary growth, primarily on the upper surface, increases the growth rate by varying growth parameters. Leveraging the higher nucleation density and growth rate in the upper surface region, the film gradually expands laterally toward the opening of the serpentine groove, ultimately achieving automatic sealing of the opening and forming a second diamond film of a certain thickness on the upper surface of the substrate.

[0044] The method of this application provides a complete process for preparing microchannel diamond film devices. Through a series of carefully designed steps, it effectively solves the technical challenges of achieving uniform growth of diamond films and channel closure inside and outside the serpentine groove structure with a high aspect ratio. First, a serpentine groove is machined on the substrate to form the foundation of the microchannel structure. Subsequently, the processed substrate is cleaned to remove contaminants, ensuring the subsequent deposition of diamond seeds and the adhesion and quality of the film layer. Next, diamond nanocrystalline powder is deposited on the inner wall of the serpentine groove through ultrasonic treatment. The cavitation effect of the ultrasound and the flow of liquid are used to effectively transport and uniformly deposit the nanocrystalline powder into the serpentine groove with a high aspect ratio, overcoming the difficulty of traditional methods in achieving effective seeding inside deep and narrow channels. At the same time, the upper surface of the substrate is treated by tilted sandblasting, which is different from the internal method. This mechanical sandblasting method, especially by rotating the substrate and controlling the tilt angle, can effectively enhance the roughness of the substrate's upper surface, promote the physical embedding of diamond micropowder, and thus significantly increase the initial nucleation density on the upper surface. The design of the tilt angle can optimize the impact effect of the particles, making them more effectively embedded in the upper surface, especially the notch area, while avoiding damage or uneven effects on the seeded seeds inside the groove, achieving differentiation and synergy with internal ultrasonic seeding. This internal and external differentiated seeding strategy is an important means to solve the problem of uniformity and rate matching of nucleation inside and outside complex microstructures, and lays the foundation for subsequent staged growth. Finally, a staged growth strategy is adopted. The first growth is mainly used to form a first diamond film of a certain thickness on the inner wall of the winding groove. The secondary growth is carried out mainly on the upper surface by changing the growth parameters to increase the growth rate. Taking advantage of the higher nucleation density and growth rate in the upper surface area, the film layer will gradually expand laterally to the notch area of ​​the winding groove, and finally achieve automatic closure of the notch and form a second diamond film of a certain thickness on the upper surface of the substrate. This staged, internal and external synergistic growth strategy solves the problem that traditional methods are difficult to simultaneously ensure internal growth quality and external channel closure, ensuring the integrity and functionality of the device structure. By means of the above method, a microchannel diamond film device having a winding microchannel can be prepared. The device comprises a substrate comprising a winding groove, a first diamond film attached to the inner wall of the groove, and a second diamond film covering the upper surface of the substrate. The first diamond film and the second diamond film are connected as a whole to enclose a winding microchannel located inside the substrate.

[0045] As a specific implementation method, a microchannel diamond film device can be prepared using the following steps: First, a serpentine groove with a high aspect ratio is machined on a silicon substrate using a deep reactive ion etching (DRIE) process. The machined silicon substrate is then cleaned, specifically by ultrasonically treating the substrate with an acetone solution to remove organic contaminants, then ultrasonically treating the substrate with a dilute hydrochloric acid solution to remove metal ion contaminants, and finally rinsing the substrate with deionized water and drying it with nitrogen. The cleaned substrate is then placed in a mixture containing diamond nanocrystal powder (particle size approximately 5-10 nm) and anhydrous ethanol and ultrasonically treated (10-30 minutes) to preferentially deposit diamond seeds on the inner walls of the serpentine groove. The substrate is then mounted on a rotating platform (rotating at approximately 10-30 rpm). A controlled flow of diamond powder (particle size approximately 100-200 nm) is sprayed onto the substrate's upper surface at an angle of approximately 18° (typically ranging from 3-20°), performing a sandblasting seeding treatment. Prior to diamond film growth, the MPCVD system's sample stage can be treated, for example, by wiping it with anhydrous ethanol. Hydrogen gas with a purity of at least 7N is then introduced into the MPCVD system at a controlled flow rate of 30-120 sccm and a pressure of 2-6 Torr. Meanwhile, the sample stage is heated to 450-500°C using a 500-1000W microwave, and the surface is plasma cleaned. The seeded substrate is then placed in the MPCVD system for diamond film growth. The growth process can be divided into primary growth and secondary growth. The primary growth process forms the first diamond film on the inner wall of the serpentine groove. The MPCVD system maintains a constant flow of hydrogen while simultaneously introducing methane gas with a purity of at least 6N. The methane flow rate is controlled to be 3%-5% of the hydrogen flow rate, and the pressure is maintained at 60-80 Torr. The substrate surface is heated to 400-600°C using microwaves at 3000-5000W. The substrate is negatively biased at -300V to -200V, and the growth duration is controlled to 1.5-2.5 hours. After the primary growth continues for a specified period, a secondary growth process is performed to automatically close the notches of the serpentine groove and form a second diamond film on the substrate surface. The secondary growth process can be divided into two stages. In the first stage, the hydrogen flow rate is controlled at 300-500sccm, the methane flow rate at 9-15sccm, and the pressure at 80-120 Torr. The substrate surface is heated to 700-800°C using microwaves at 4000-7000W. After completing the first stage, the second stage of growth is carried out. The hydrogen flow rate can be maintained at 300-500 sccm, the methane gas flow rate can be maintained at 9-15 sccm, the gas pressure can be controlled at 90-130 Torr, and the substrate surface can be heated to 800-950°C by 5000-8000W microwaves.Through the above steps, a microchannel diamond film device with a winding microchannel can be obtained.

[0046] This fabrication method effectively achieves uniform and efficient diamond seed deposition and film growth within serpentine grooves with high aspect ratios, while simultaneously coordinating the diamond growth rates inside and outside the channels. Ultimately, this method achieves reliable and automatic sealing of the serpentine groove openings, forming a three-dimensional diamond composite structure with a complete structure and continuous interfaces. This method addresses the technical challenges of achieving uniform growth of diamond films and channel sealing within complex microstructures, providing a viable approach for fabricating high-performance microchannel diamond film devices.

[0047] It should be noted that after obtaining a microchannel diamond film device with a winding microchannel, stop introducing methane and slowly reduce the hydrogen flow rate, air pressure and microwave power to break the vacuum before taking out the sample; when taking out the sample after breaking the vacuum, the temperature should be slowly lowered (less than 0.8°C per second) and the power should be slowly lowered to avoid cracks and other defects on the sample surface due to thermal stress that affect the quality; during the slow cooling process, the hydrogen flow rate should not be reduced too quickly, and an appropriate gas flow rate should be maintained to prevent impurities from entering the reaction chamber and to avoid oxidation or contamination of the diamond surface.

[0048] In some embodiments, the specific steps in step S2 include:

[0049] The substrate is ultrasonically treated with an acetone solution to remove organic pollutants on the surface of the substrate, thereby obtaining a substrate after the first cleaning;

[0050] The substrate after the first cleaning is subjected to ultrasonic treatment using a dilute hydrochloric acid solution to remove metal ion contaminants on the surface of the substrate, thereby obtaining a substrate after the second cleaning;

[0051] The substrate after the second cleaning was rinsed with deionized water and dried with nitrogen to remove all residual liquid, thereby obtaining a cleaned substrate.

[0052] This cleaning method, through a step-by-step, targeted cleaning process, aims to thoroughly remove all contaminants from the substrate surface, providing a clean surface for subsequent diamond seed deposition and thin film growth. Specifically, the substrate is first ultrasonically treated with an acetone solution for 5-10 minutes. Acetone, as an organic solvent, effectively dissolves or disperses organic contaminants that may be present on the substrate surface, such as residual grease and fingerprints from machining. Combined with the cavitation effect generated by ultrasonic treatment, it enhances the cleaning solution's penetration and stripping ability, making it particularly valuable for removing organic matter from microstructures such as serpentine grooves. This step provides a preliminary removal of organic impurities from the substrate surface, laying the foundation for subsequent inorganic cleaning. Next, the substrate, after this initial cleaning, is ultrasonically treated with a 0.1M dilute hydrochloric acid solution for 1-5 minutes. Dilute hydrochloric acid, as an acidic solution, effectively dissolves or removes metal ion contaminants that may be present on the substrate surface, such as metal particles produced by machining tool wear or metal impurities precipitated from the substrate material. Combined with ultrasonic treatment, the removal efficiency of metal ion contaminants can be further improved, ensuring that no metal impurities remain on the substrate surface that could affect diamond nucleation and growth. Finally, the substrate after the second cleaning step is rinsed with deionized water and dried with nitrogen. While the first two steps involved chemical reagents, this step uses high-purity deionized water for thorough rinsing, aiming to completely remove any chemical residues remaining on the substrate surface after the first two cleaning steps, as well as any dissolved or stripped contaminants. The use of deionized water ensures the purity of the cleaning medium itself and avoids the introduction of new impurities. The final nitrogen drying step quickly removes moisture from the substrate surface, preventing residual water stains and surface oxidation, ensuring a dry and clean substrate surface and ideal surface conditions for the subsequent diamond seed deposition step. This step-by-step, targeted cleaning strategy achieves a highly clean substrate surface, effectively aligning with the subsequent diamond seed deposition and film growth steps, ensuring uniform seed distribution and strong adhesion, as well as dense growth of the diamond film and good adhesion to the substrate.

[0053] In some embodiments, step S5 further includes the following steps:

[0054] Use anhydrous ethanol to wipe the sample stage in the MPCVD system; the sample stage is used to support the substrate later;

[0055] The MPCVD system is controlled to introduce hydrogen gas and the sample stage is heated to perform plasma cleaning on the surface of the sample stage.

[0056] The "sample stage" refers to the component used to support the substrate on which the diamond film is to be grown in the MPCVD system. It can be made of materials such as graphite, molybdenum, and ceramics. "Anhydrous ethanol" refers to ethanol that meets a certain purity standard. As an organic solvent, it can be used to dissolve and remove organic matter, grease, and other pollutants from the surface of the sample stage. "Plasma cleaning" refers to a technology that uses plasma formed by gas excited under specific conditions to treat the surface of a material. It can be achieved by using radio frequency plasma, microwave plasma, etc., and the active particles in the plasma react chemically or physically bombard with surface pollutants to achieve the purpose of cleaning the surface.

[0057] This application achieves effective sample stage cleaning through the combination of the above-mentioned technical features. Its operating principle is as follows. By adding a cleaning step to the MPCVD system sample stage before the diamond growth step, this solution can address the problem of surface contaminants on the sample stage affecting the quality of subsequent diamond growth, providing a clean reaction environment for obtaining high-quality diamond films. Before diamond growth, the sample stage is first wiped with anhydrous ethanol. Anhydrous ethanol, as an organic solvent, can dissolve and remove contaminants such as organic matter and grease that may be present on the sample stage surface. Wiping, as a physical cleaning method, combined with the use of a solvent, can remove dirt adhering to the sample stage surface. Anhydrous ethanol is used instead of an aqueous solvent to avoid the introduction of moisture into the system's internal environment, which can affect the stability and purity of the plasma and even introduce oxygen impurities, adversely affecting diamond growth. Subsequently, within the MPCVD system, the control system introduces hydrogen gas and performs plasma cleaning by heating the sample stage. This step is performed internally within the diamond growth equipment. Controlling the hydrogen flow to the MPCVD system provides the reactive gas foundation for generating the hydrogen plasma. The active hydrogen atoms and ions in the hydrogen plasma have reducing and etching capabilities. By heating the sample stage, the activity of atoms on the sample stage surface is increased, enhancing the reaction between the plasma and surface contaminants. Hydrogen plasma can chemically react with inorganic contaminants such as oxides and carbides that may remain on the sample stage surface, converting them into gaseous substances that are removed by the vacuum system, or removing surface adsorption layers and particles through physical bombardment. This internal cleaning of the device avoids secondary contamination caused by the sample stage being exposed to air again after external cleaning, ensuring the clean state of the sample stage before diamond growth. By combining the two cleaning methods of wiping with anhydrous ethanol and hydrogen plasma cleaning inside the device, this solution can remove various contaminants on the surface of the sample stage, providing a clean substrate environment for the subsequent uniform and dense growth of diamonds on the substrate. This sample stage cleaning step and other steps in the preparation method, such as machining winding grooves on the substrate, cleaning the processed substrate, and performing seed deposition and sandblasting on the cleaned substrate, work together to form the final device. The initial substrate treatment prepares the surface to be grown, while the sample stage cleaning prepares the growth environment. The combination of the two can achieve the growth of high-quality complex structure diamond films, thereby helping to improve the quality and performance of diamond films, and ultimately improve the overall performance of microchannel diamond film devices.

[0058] In some embodiments, the step of controlling the MPCVD system to introduce hydrogen gas and performing plasma cleaning on the surface of the sample stage by heating the sample stage includes:

[0059] The MPCVD system is controlled to introduce hydrogen with a purity of not less than 7N, and the hydrogen flow rate is controlled at 30-120sccm and the gas pressure is controlled at 2-6Torr. At the same time, the sample stage is heated to 450-500℃ by a 500-1000W microwave to perform plasma cleaning on the surface of the sample stage; the hydrogen is used for ignition.

[0060] This solution achieves optimized cleaning of the sample stage surface by precisely controlling various process parameters during plasma cleaning of the sample stage in an MPCVD system. Specifically, hydrogen gas with a purity of at least 7N ensures a pure plasma environment and minimizes potential impurities introduced by the gas itself. This is crucial for subsequent diamond film growth, as any surface contaminants can serve as nucleation sites for non-diamond phases or inhibit diamond growth. Controlling the hydrogen flow rate between 30-120 sccm and the pressure between 2-6 Torr ensures stable plasma generation while regulating the plasma density and concentration of active hydrogen species. This optimal flow rate and pressure range ensures the plasma is sufficiently active to react with or bombard contaminants on the sample stage surface, while avoiding excessive activity that could cause unnecessary etching or damage. Simultaneously, the sample stage is heated to 450-500°C using microwaves at 500-1000W. The microwave power provides the energy required to excite the hydrogen gas to generate the plasma, and the optimal power range ensures the generation of a sufficiently dense plasma. At this point, nano-diamonds begin to grow and deposit on the surface of the micron-sized diamond powder, and the micron-sized diamond powder particles come into contact and connect with each other as the nano-diamonds grow. Initially, there are gaps between the micron-sized diamonds. As the nano-diamonds continue to deposit, the micron-sized diamond powder will continue to grow larger and eventually come into contact with each other and grow into a whole. Heating the sample stage to a specific temperature can increase the reactivity or volatility of surface contaminants, enhancing the effectiveness of plasma cleaning. This temperature range is relatively low, which helps to avoid thermal damage or structural changes to the sample stage material. Hydrogen is used as the working gas and is excited to produce plasma under the action of microwave energy. The active hydrogen species in the plasma can effectively react with contaminants such as hydrocarbons and oxides on the sample stage surface, converting them into gaseous products that are removed by the vacuum system. Through the coordinated control of the above parameters, this scheme provides an efficient and gentle plasma cleaning method, providing a clean and activated surface for subsequent diamond film growth. This, combined with the subsequent diamond seed deposition and growth steps, jointly guarantees the performance of the final microchannel diamond film device.

[0061] By controlling the MPCVD system to introduce hydrogen of a specific purity, flow rate, and pressure, combined with plasma cleaning within a specific range of microwave power and sample stage temperature, residual contaminants on the sample stage surface can be effectively removed, resulting in a highly clean surface. This provides a good foundation for subsequent diamond seed deposition and diamond film growth on the substrate, helping to improve the nucleation density, uniformity, and crystal quality of the diamond film, thereby ensuring that the resulting microchannel diamond film device has excellent thermal conductivity and structural integrity.

[0062] In some embodiments, the specific steps of performing the first growth in step S5 include:

[0063] The MPCVD system is controlled to maintain the flow of hydrogen while also introducing methane gas, and a negative bias voltage is set on the substrate to promote the growth of diamond on the inner wall of the winding groove, thereby forming the first diamond film. The negative bias voltage can enhance the transport and bombardment effect of plasma active species in the high aspect ratio microchannel, effectively improving the nucleation density inside the channel and the density of the film layer, and solving the problem of insufficient deposition at the bottom of the channel in traditional methods.

[0064] An MPCVD system refers to a microwave plasma chemical vapor deposition system, a commonly used tool for growing diamond thin films that can be configured in a variety of ways. A negative bias voltage is a negative potential applied to the substrate and can be a constant DC voltage or a pulsed voltage. Plasma active species are particles with high chemical reactivity generated in the plasma through processes such as ionization, excitation, or dissociation. These include hydrocarbon radicals, various ions (such as H+ and CHx+), and excited atoms or molecules. A high-aspect-ratio microchannel is a microstructure with a depth-to-width ratio significantly greater than 1, posing a challenge to the transport of materials within the channel. The transport and bombardment effect refers to the process by which particles in the plasma, driven by forces such as electric fields and concentration gradients, migrate toward the substrate surface (transport) and collide with it (bombardment). This bombardment can clean the surface, provide energy, or promote chemical reactions. Nucleation density refers to the number of diamond nuclei per unit area, reflecting the density of the starting points for diamond growth. Film density refers to the compactness of the internal structure of the film material, the number of pores and defects, which directly affects the physical properties of the film, such as thermal conductivity.

[0065] Based on the above technical understanding, the solution of the present application promotes the growth of diamond on the inner wall of the winding groove to form a first diamond film by applying a negative bias to the substrate during the first growth in the MPCVD system. Specifically, hydrogen and methane gases are introduced into the MPCVD system, and microwave energy is used to excite a plasma containing active species required for diamond growth. In the traditional growth process, the transport of these active species to the deep part of the high aspect ratio winding groove is restricted, resulting in insufficient nucleation and growth in the deep part, especially in the bottom area. The present solution forms an electric field near the surface of the substrate by applying a negative bias to the substrate. The charged active species in the plasma, especially the positively charged ions, will be more effectively transported to the substrate surface under the attraction and acceleration of this negative electric field, and bombard the substrate surface, especially the inner wall of the winding groove, with higher energy. This enhanced transport and bombardment effect is crucial to overcoming the transport obstacles inside the high aspect ratio structure, enabling more active species to reach the deep part of the channel, and effectively activate and clean the inner wall surface of the channel, thereby promoting the formation of diamond nuclei. Therefore, applying a negative bias significantly increases the diamond nucleation density within the serpentine grooves and promotes dense film growth, thus resolving the technical issue of insufficient diamond deposition at the channel bottom due to insufficient active species transport and bombardment in traditional methods. This negative bias technique, combined with the fundamental diamond growth process of hydrogen and methane in the MPCVD system, forms a synergistic overall solution that effectively improves the quality of diamond film growth within high-aspect-ratio microchannels.

[0066] To further illustrate the present invention, a specific implementation example can be provided. For example, after cleaning the substrate and seeding the substrate, the substrate is placed in the reaction chamber of an MPCVD system. After evacuation to a base vacuum, hydrogen and methane gases are introduced, and the gas flow rates and chamber pressure are adjusted to preset ranges. A microwave generator generates microwaves, coupling energy into the reaction chamber to excite the hydrogen and methane gases to form a plasma. Simultaneously, a heating device controls the substrate surface temperature within a temperature range suitable for diamond growth. During this growth process, a negative potential is applied to the substrate via a power supply connected to the substrate or sample stage. The aforementioned gas composition, flow rate, pressure, microwave power, substrate temperature, and negative bias voltage are maintained under certain conditions for a period of time. Under these conditions, the active species in the plasma are accelerated and directed toward the inner wall of the serpentine groove by the electric field generated by the negative bias voltage, enhancing bombardment of the inner wall and promoting the formation and growth of diamond nuclei. After a predetermined growth period, a first diamond film of a predetermined thickness is formed on the inner wall of the serpentine groove.

[0067] By applying a negative bias to the substrate during initial growth in the MPCVD system, the proposed method enhances the transport and bombardment of plasma active species within high-aspect-ratio microchannels. This effectively increases the diamond nucleation density and film density within the channel, thereby resolving the technical issues associated with traditional methods, such as insufficient diamond deposition at the channel bottom due to ineffective active species arrival and insufficient bombardment.

[0068] In some embodiments, the step of controlling the MPCVD system to maintain the flow of hydrogen while simultaneously introducing methane gas, and setting a negative bias voltage on the substrate to promote diamond growth on the inner wall of the serpentine groove to form the first diamond film includes:

[0069] The MPCVD system is controlled to maintain a constant hydrogen flow rate, while methane gas with a purity of not less than 6N is introduced. The methane gas flow rate is controlled to 3%-5% of the hydrogen flow rate (i.e., 0.9-6sccm) and the gas pressure is controlled to 60-80Torr. The substrate surface is heated to 400-600°C using 3000-5000W microwaves. At the same time, the negative bias voltage of the substrate is set to -300V to -200V, and the growth time is controlled to 1.5-2.5h to obtain the first diamond film. Using a negative bias voltage of -300V to -200V can enhance the penetration and bombardment effect of plasma on the inside of the channel, promote the deposition of activated carbon groups at the bottom of the channel, and thus solve the problem of diamond powder connection in high aspect ratio structures.

[0070] This approach aims to optimize the growth quality of diamond films on the inner walls of high-aspect-ratio serpentine grooves by precisely controlling key process parameters during the initial growth process, addressing issues such as uneven film formation, insufficient density, or weak grain connectivity. The MPCVD system maintains a constant hydrogen flow rate while simultaneously introducing methane gas with a purity of at least 6N. The methane flow rate is controlled to 3%-5% of the hydrogen flow rate, and the pressure is controlled at 60-80 Torr, providing the carbon source concentration and reaction environment necessary for diamond growth. Methane concentration and pressure within a defined range facilitate carbon source distribution and transport of plasma active species within high-aspect-ratio structures. Microwaves at 3000-5000W are used to heat the substrate surface to 400-600°C, creating the conditions necessary for plasma generation and substrate heating, facilitating growth in high-aspect-ratio structures while reducing thermal stress. At the same time, the negative bias voltage of the substrate is set to -300V to -200V. This limited range of negative bias voltage can enhance the penetration and bombardment effect of the plasma on the interior of the high aspect ratio channel, guiding the charged active carbon groups to move to the bottom of the channel and deposit, thereby promoting nucleation and growth inside the channel, solving the problems of insufficient deposition at the bottom of the channel and weak connection of diamond grains, and improving the density and continuity of the film layer. The growth time is controlled at 1.5-2.5h to ensure that under the above parameter combination, a first diamond film with a certain thickness and quality that meets the requirements can be grown on the inner wall of the channel, laying the foundation for subsequent secondary growth and channel closure. The coordinated control of these parameters enables the growth of high-quality diamond films in high aspect ratio structures.

[0071] By precisely controlling the hydrogen flow rate, methane purity and flow rate, gas pressure, microwave power, substrate surface temperature, negative bias voltage, and growth duration during the initial growth process within specific ranges, this solution effectively addresses the issues of uneven diamond film growth, insufficient density, and weak diamond grain connectivity within high-aspect-ratio microchannels. The limited negative bias voltage enhances plasma penetration and bombardment of the channel interior, promoting the deposition of activated carbon groups at the channel bottom, increasing the nucleation density and film density within the channel, and ensuring strong connectivity of the diamond grains, thereby achieving the first diamond film of satisfactory quality within the high-aspect-ratio structure.

[0072] In some embodiments, the specific steps of performing secondary growth in step S5 include:

[0073] After the initial growth continues for a specified period of time, the diamond on the upper surface of the substrate is prompted to grow in the first and second stages in sequence by changing the microwave power, substrate surface temperature, hydrogen flow rate, methane gas flow rate and gas pressure, thereby forming a second diamond film. The growth duration of the first and second stages is determined by the thickness of the second diamond film to be formed. It is usually necessary to pre-determine the growth rate under specific parameters through experiments, and then calculate the total time based on the target film thickness and allocate it proportionally to the two stages.

[0074] Changing microwave power, substrate surface temperature, hydrogen flow rate, methane flow rate, and gas pressure refers to adjusting key process parameters in the MPCVD system that influence the diamond growth process. Microwave power influences plasma generation and energy distribution; substrate surface temperature affects carbon source adsorption, decomposition, and crystal growth dynamics on the substrate surface; hydrogen flow rate influences the concentration of active hydrogen atoms in the plasma, which in turn affects carbon source decomposition and non-diamond phase etching; methane flow rate provides the carbon source for diamond growth; and gas pressure influences plasma morphology and the transport of active species to the substrate surface. By adjusting these parameters, diamond nucleation density, growth rate, crystal quality, grain size, and film stress can be manipulated. The first and second stages of growth divide the entire secondary growth process into two consecutive phases with different growth conditions. This phased design allows for optimized process parameters for different growth objectives, such as focusing on initial film formation and densification in one phase and rapid thickening in the other. The growth duration is determined by the desired thickness of the second diamond film, meaning the total growth duration is determined based on the desired final film thickness. The growth rate under specific parameters is pre-determined through experiments, and the total time is then calculated based on the target film thickness and allocated proportionally to the two stages. This is a method based on experimental data and engineering practice to determine the specific growth duration of each stage, ensuring that the final film layer reaches the predetermined thickness and that the contribution of each stage of growth to the overall film structure and performance is reasonably controlled.

[0075] Based on the above technical features, the working principle of the secondary growth method of the present application can be explained as follows: After the initial growth is completed and the first diamond film is formed on the inner wall of the serpentine groove, secondary growth is carried out in stages, and the MPCVD process parameters are adjusted at different stages to achieve fine control of the growth process of the diamond film layer on the upper surface of the substrate. The first stage of growth can adopt a set of parameters, such as a lower growth rate, to ensure stable growth of the diamond seed crystal, form a continuous and dense initial film layer, and begin to close the notch of the serpentine groove. The parameter selection at this stage can help avoid high temperature stress causing cracking of the substrate or film layer, especially for microchannel structures with a high aspect ratio. After completing the first stage, the process parameters are adjusted to enter the second stage of growth. The second stage can adopt another set of parameters, such as a higher growth rate, to quickly thicken the diamond film layer to the target thickness. The parameter selection at this stage can promote the recrystallization and densification of the diamond grains, thereby improving the quality of the film layer. The total duration of the entire secondary growth is determined based on the expected thickness of the second diamond film and calculated based on the experimentally measured growth rate. The total duration is then proportionally allocated to the first and second stages based on their respective contributions to the total thickness or overall growth process. This phased, parameter-adjustable growth method, combined with the film layer on the inner wall of the channel formed during the initial growth, enables the film layer on the upper surface of the substrate to effectively seal the notch, forming a structurally complete, interface-continuous three-dimensional diamond composite structure.

[0076] By adopting the above method, the present application can achieve the following technical effects: by refining the secondary growth process into two stages and changing the growth parameters between the stages, the growth process of different stages can be optimized in a targeted manner. For example, in the first stage, the focus is on the formation and densification of the initial film layer, and in the second stage, the focus is on rapid thickening and grain optimization. This staged control makes it possible to better balance the growth rate, film quality and stress control, thereby obtaining a high-quality, dense, thickness-controlled second diamond film and effectively closing the notch of the winding groove. This overcomes the problem that simple one-time growth is difficult to take into account multiple growth goals, improves the film quality and notch sealing effect, and can optimize the growth cycle while ensuring the quality of the film.

[0077] In some embodiments, the step of forming the second diamond film by changing microwave power, substrate surface temperature, hydrogen flow rate, methane flow rate, and gas pressure to sequentially promote the growth of diamond on the upper surface of the substrate in the first and second stages includes:

[0078] By controlling the hydrogen flow rate at 300-500 sccm, the methane flow rate at 9-15 sccm, and the gas pressure at 80-120 Torr, and heating the substrate surface to 700-800°C using 4000-7000W microwaves, the diamond on the substrate surface undergoes the first stage of growth. The first stage ensures the stable growth of the diamond seed crystals, forming a continuous and dense initial film layer; avoids cracking of the substrate or film layer caused by high temperature stress, especially for high aspect ratio microchannel structures; and controls the growth rate and reduces defects by using a low methane concentration.

[0079] After completing the first stage of growth, the hydrogen flow rate is maintained at 300-500sccm, the methane gas flow rate is maintained at 9-15sccm, and the gas pressure is controlled at 90-130Torr. The substrate surface is heated to 800-950°C using 5000-8000W microwaves, which promotes the second stage of growth of the diamond on the upper surface of the substrate to obtain a second diamond film. The functions of the second stage include: increasing the growth rate and rapidly thickening the diamond film layer to the target thickness; high temperature promotes the recrystallization and densification of diamond grains, improving the film quality and thermal conductivity; and maintaining a high active carbon source supply through higher methane flow and pressure to ensure the uniformity of the film layer.

[0080] The solution of this application subdivides the secondary growth process into two stages, and sets specific process parameter ranges and target effects for each stage. In the first stage of growth, the hydrogen flow rate is controlled at 300-500sccm, the methane gas flow rate is controlled at 9-15sccm and the gas pressure is controlled at 80-120Torr, and the substrate surface is heated to 700-800°C by 4000-7000W microwaves. These parameters set relatively mild growth conditions, which are used to ensure that the diamond seeds can grow stably and form a continuous and dense initial film layer, which lays the foundation for subsequent rapid thickening. By controlling the growth within a lower temperature, microwave power and methane concentration range, it is possible to effectively avoid cracking of the substrate or the formed film layer due to excessive growth stress, which is especially important for microchannel structures with a high aspect ratio, ensuring the integrity of the structure. At the same time, controlling the growth rate by a lower methane concentration helps to reduce defects that may be introduced during the growth process, thereby ensuring the quality of the initial film layer. After the first growth phase, the second growth phase begins. The substrate surface is heated to 800-950°C using microwaves at 5000-8000W, maintaining a hydrogen flow rate of 300-500 sccm, a methane flow rate of 9-15 sccm, and a pressure of 90-130 Torr. These parameters establish relatively aggressive growth conditions, significantly increasing the diamond growth rate, enabling rapid film growth to the target thickness and improving production efficiency. The higher temperature and microwave power promote recrystallization and densification of the diamond grains, further improving film quality and thermal conductivity. Maintaining a continuous supply of highly active carbon sources through higher microwave power and pressure ensures uniform film growth during the rapid growth process, ultimately forming a structurally complete and high-performance second diamond film. The serpentine grooves are automatically sealed, forming complete internal microchannels. This phased, parameter-optimized growth strategy specifically addresses the challenges of growing high-quality diamond films on surfaces with complex microstructures. This secondary growth method, combined with the previous differentiated seeding (ultrasonic seeding on the channel inner wall and inclined sandblasting seeding on the upper surface) and primary growth (diamond film growth on the channel inner wall), works together to form a diamond film on the channel inner wall of a winding groove structure with a high aspect ratio, while also effectively sealing the groove opening through the growth of the upper surface film, ultimately obtaining a diamond film device with internal microchannels. The initial differentiated seeding provides a higher seed density on the upper surface, and the primary growth establishes a growth foundation on the channel inner wall. The optimized secondary growth of this scheme leverages this foundation to ensure rapid, high-quality growth of the upper surface film and reliable sealing of the groove opening by precisely controlling the growth process, thus overcoming the technical difficulty of achieving uniform, dense, and defect-free diamond film growth on high-aspect-ratio structures.

[0081] In this document, relational terms such as first and second, etc. are used merely to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any actual relationship or order between these entities or operations.

[0082] Descriptions with reference to the terms "one embodiment," "certain embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0083] The foregoing description is merely an embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A microchannel diamond film device, comprising a substrate (100), characterized in that: The substrate (100) is provided with a winding groove (110), and the depth of the winding groove (110) is greater than the width; the microchannel diamond film device also includes a first diamond film (200) attached to the inner wall of the winding groove (110) and a second diamond film (300) covering the upper surface of the substrate (100), the first diamond film (200) and the second diamond film (300) are connected as a whole to enclose a winding microchannel located inside the substrate (100), and the winding microchannel includes an inlet and an outlet for a cooling medium to enter and exit.

2. The microchannel diamond film device according to claim 1, characterized in that The substrate (100) is made of graphite, copper, aluminum, silicon, ceramic or aluminum nitride.

3. A method for preparing a microchannel diamond film device according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1. Processing a winding groove on the substrate; S2. Cleaning the processed substrate; S3. The cleaned substrate is placed in a mixture of diamond nanocrystal powder and anhydrous ethanol and ultrasonically treated to deposit diamond seeds on the inner wall of the winding groove; S4. The substrate is mounted on a rotating platform and an airflow with diamond powder is controlled to spray the airflow at a specified tilt angle toward the upper surface of the substrate to achieve sandblasting seeding treatment on the upper surface of the substrate; S5. Place the substrate in an MPCVD system for primary growth, and after the primary growth continues for a specified period of time, perform secondary growth to obtain a microchannel diamond film device with a winding microchannel; the primary growth is used to form a first diamond film of a certain thickness on the inner wall of the winding groove; the secondary growth is used to automatically close the notch of the winding groove and form a second diamond film of a certain thickness on the upper surface of the substrate.

4. The preparation method according to claim 3, characterized in that The specific steps in step S2 include: The substrate is ultrasonically treated with an acetone solution to obtain a substrate after a first cleaning; Ultrasonic treatment is performed on the substrate after the first cleaning using a dilute hydrochloric acid solution to obtain a substrate after the second cleaning; The substrate after the second cleaning was cleaned with deionized water and dried with nitrogen to obtain a cleaned substrate.

5. The preparation method according to claim 3, characterized in that Before step S5, the method further includes the following steps: Use anhydrous ethanol to wipe the sample stage in the MPCVD system; the sample stage is used to support the substrate later; The MPCVD system is controlled to introduce hydrogen gas and the sample stage is heated to perform plasma cleaning on the surface of the sample stage.

6. The preparation method according to claim 5, characterized in that The steps of controlling the MPCVD system to introduce hydrogen gas and performing plasma cleaning on the surface of the sample stage by heating the sample stage include: The MPCVD system is controlled to introduce hydrogen with a purity of not less than 7N, and the hydrogen flow rate is controlled at 30-120sccm and the gas pressure is controlled at 2-6Torr. At the same time, the sample stage is heated to 450-500℃ by a 500-1000W microwave to perform plasma cleaning on the surface of the sample stage.

7. The preparation method according to claim 6, characterized in that The specific steps of performing the first growth in step S5 include: The MPCVD system is controlled to keep introducing hydrogen gas while introducing methane gas, and a negative bias voltage is set on the substrate to promote the growth of diamond on the inner wall of the winding groove to form the first diamond film.

8. The preparation method according to claim 7, characterized in that The steps of controlling the MPCVD system to keep hydrogen flowing while simultaneously flowing methane gas, and setting a negative bias voltage on the substrate to promote diamond growth on the inner wall of the serpentine groove to form the first diamond film include: The MPCVD system is controlled to maintain a constant hydrogen flow rate, while introducing methane gas with a purity of not less than 6N, and the methane gas flow rate is controlled to 3%-5% of the hydrogen flow rate and the gas pressure is controlled to 60-80 Torr, and the substrate surface is heated to 400-600°C by a 3000-5000W microwave, while the negative bias voltage of the substrate is set to -300V to -200V, and the growth time is controlled to 1.5-2.5h to obtain the first diamond film.

9. The preparation method according to claim 8, characterized in that The specific steps of performing secondary growth in step S5 include: After the initial growth continues for a specified period of time, the diamond on the upper surface of the substrate is prompted to grow in the first and second stages in sequence by changing the microwave power, substrate surface temperature, hydrogen flow rate, methane gas flow rate and gas pressure, thereby forming the second diamond film; the growth duration of the first and second stages is determined by the thickness of the second diamond film to be formed.

10. The preparation method according to claim 9, characterized in that The steps of forming the second diamond film by changing microwave power, substrate surface temperature, hydrogen flow rate, methane gas flow rate, and gas pressure to sequentially promote the growth of diamond on the upper surface of the substrate in the first and second stages include: By controlling the hydrogen flow rate to 300-500 sccm, the methane flow rate to 9-15 sccm, and the gas pressure to 80-120 Torr, and heating the substrate surface to 700-800°C with 4000-7000W microwaves, the first stage of diamond growth on the substrate surface is promoted; After completing the first stage of growth, the hydrogen flow rate is maintained at 300-500sccm, the methane gas flow rate is maintained at 9-15sccm and the gas pressure is controlled at 90-130Torr, and the substrate surface is heated to 800-950°C by 5000-8000W microwaves to promote the second stage of growth of diamonds on the upper surface of the substrate, thereby obtaining the second diamond film.

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