Stripping-free self-falling diamond film as well as preparation method and application thereof

Abstract

The invention discloses a preparation method of a stripping-free self-falling diamond film, the diamond film and application of the diamond film, the preparation method comprises the steps that a transition layer is deposited on a silicon substrate, and the thermal expansion coefficient of a material of the transition layer is higher than that of the silicon substrate and that of diamond; a diamond seed crystal layer is deposited on the transition layer, a diamond thick film is deposited on the diamond seed crystal layer, cooling is conducted after deposition is completed, and the cooling rate is 20-40 DEG C / min; and the edge of the diamond thick film is cut through laser, so that the diamond thick film automatically falls off, and the self-supporting diamond thick film is obtained. By means of the preparation method, the diamond film can be prepared in a self-falling and stripping-free mode, and the self-supporting diamond thick film which is low in warping degree, complete in structure and high in heat conduction performance can be prepared.

Description

Technical Field

[0001] This invention belongs to the field of diamond material technology, specifically relating to a self-detaching diamond film that does not require peeling, its preparation method, and its application. Background Technology

[0002] As the output power of power electronic devices continues to increase, the high temperatures generated inside these devices due to heat will seriously affect the reliability of the devices and circuits. Therefore, heat dissipation of power electronic devices has become an urgent issue to be addressed in device design and manufacturing.

[0003] Diamond materials, due to their ultra-high thermal conductivity (up to ~2000 W / m·K), ultra-low coefficient of thermal expansion, electrical insulation, and high strength, have become the "ultimate solution" among current thermal management materials. If diamond films can be directly bonded to the back side of high-power chips (such as GaN, SiC, etc.), it can not only significantly reduce near-junction thermal resistance and junction temperature, but also improve device lifespan and integration density, making it a key thermal interface material for 3D integrated chip packaging.

[0004] Currently, the most common method for synthesizing artificial diamond films is to use MPCVD technology to epitaxially grow them on silicon substrates, resulting in a silicon / diamond composite film. However, silicon has a thermal conductivity of only 150 W / m·K at room temperature, which is a large thermal resistance compared to diamond, severely affecting the heat dissipation performance of diamond. Therefore, it is necessary to peel off the silicon substrate from the diamond composite film. Diamond film materials are often grown on silicon substrates using methods such as hot filament chemical vapor deposition (HFCVD) and microwave plasma chemical vapor deposition (MPCVD) to form substrate-attached films. However, the peeling method involves wet etching of silicon for substrate removal. When the silicon substrate is relatively thick, the etching efficiency of the above methods is very low, and the surface of the diamond film obtained by etching and peeling is uneven, resulting in poor quality.

[0005] Patent application CN119433485A discloses an easily peelable diamond film and its preparation method, including the following steps: selecting a smooth silicon wafer as a substrate; activating the silicon wafer surface with plasma; coating the activated silicon wafer surface with nanodiamond seed crystals; transferring the seed-coated silicon wafer into an MPCVD diamond growth apparatus; in the initial stage of diamond film growth, the silicon wafer surface temperature is below 750 °C; in addition to hydrogen and carbon-containing gases, an appropriate amount of nitrogen-containing gas is introduced into the process gas; then, the cavity pressure, microwave power, and gas formulation are adjusted, and the temperature is further increased to a suitable range for diamond growth; after the diamond film grows to a predetermined thickness, it is cooled and removed. The diamond film grown by this method maintains its integrity and is crack-free, while ensuring complete peeling of the diamond film from the silicon wafer using physical methods. However, the above method still involves chemical bonding between silicon and diamond, resulting in loss of the diamond film during physical peeling.

[0006] Patent application CN107400871A discloses a method for preparing a diamond film based on a silicon substrate. The method involves forming a hydrogen layer beneath the surface of a silicon wafer substrate, then generating a diamond film on the surface of the silicon wafer substrate with the hydrogen layer. The silicon wafer substrate and the diamond film are then separated by an electrochemical peeling method from the hydrogen ion layer, forming a self-supporting diamond film. A silicon wafer substrate layer is formed on the surface of the self-supporting diamond film to facilitate the repair and leveling of machining allowances, thus avoiding damage to the diamond film during the peeling process. The peeling is performed from the silicon wafer substrate with the hydrogen layer. However, the above peeling method is difficult to achieve peel-free, self-detachment. Summary of the Invention

[0007] This invention provides a method for preparing a self-detaching diamond film without peeling. This method enables the preparation of diamond films that are self-detaching and peel-free, and can produce self-supporting thick diamond films with low warpage, intact structure, and high thermal conductivity.

[0008] This invention provides a method for preparing a peel-free, self-detaching diamond film, comprising: A transition layer is deposited on a silicon substrate, wherein the coefficient of thermal expansion of the transition layer material is higher than that of the silicon substrate and diamond. A diamond seed crystal layer is deposited on the transition layer, and a diamond thick film is deposited on the diamond seed crystal layer. After deposition, the temperature is cooled at a rate of 20–40 °C / min. Laser cutting is used to cut the edge of the diamond thick film, allowing the diamond thick film to detach on its own and thus obtain a self-supporting diamond thick film.

[0009] This invention controls the cooling rate and sets a transition layer so that the diamond thick film can be peeled off without peeling during the cooling process under stress, and can then detach itself under the action of laser. If the cooling rate is too fast, the stress concentrated on the diamond will be too great, which may cause the diamond to crack during the cooling process. If the cooling rate is too slow, the stress will be released slowly, and without sufficient stress, the diamond cannot detach itself.

[0010] During the deposition of a diamond thick film, the diamond at the edge will wrap around the silicon substrate, making it impossible for the diamond thick film to detach itself. This invention utilizes a laser to cut through and cut the edge of the diamond thick film, so that the diamond thick film can detach itself from the silicon substrate.

[0011] This invention utilizes a method to achieve complete self-supporting peeling of large-size, high-thickness diamond films without the need for external mechanical or chemical peeling methods; this invention employs a sandwich structure strategy to form a stress gradient structure, effectively releasing interfacial stress and avoiding warping and cracking of the diamond film.

[0012] Compared with chemical etching stripping, this process is green, pollution-free, simple, and efficient, reducing manufacturing costs and making it suitable for large-scale production; compared with mechanical stripping methods, this method can be used to strip thicker films.

[0013] Preferably, the material of the transition layer is one of aluminum oxide (Al2O3), aluminum nitride (AlN), silicon nitride (Si3N4), or silicon carbide (SiC).

[0014] The thermal expansion coefficients of the transition layer materials provided by the present invention are all higher than those of silicon substrates and diamond, and combined with a suitable cooling rate, the self-detachment of diamond thick films can be achieved.

[0015] More preferably, the material of the transition layer is one of aluminum nitride (AlN), silicon nitride (Si3N4), or silicon carbide (SiC).

[0016] The present invention further defines the material of the transition layer, resulting in a better coefficient of thermal expansion. This coefficient of thermal expansion is higher than that of silicon substrate and diamond, and the surface of the self-detaching thick diamond film is smoother, reducing the risk of detachment and cracking during the growth or cooling of the thick diamond film.

[0017] The transition layer provided by this invention is a nanoscale thin film deposited on a silicon substrate. Its function is to form a sandwich stack structure of "silicon / high expansion coefficient transition layer / diamond thick film" to amplify the interlayer stress during cooling. In contrast, materials such as silicon carbide in the prior art are generally used as an integral substrate with a thickness much greater than the transition layer provided in this application. They only form a simple two-layer structure with the diamond layer, and the stress state is completely different.

[0018] Because the coefficient of thermal expansion of the transition layer in this application is higher than that of silicon and diamond, high interfacial stress can be generated during cooling. If a rapid cooling rate of 50–100 ℃ / min is used, the diamond thick film is prone to cracking or severe warping in experiments, making it impossible to obtain a complete self-supporting film. Therefore, the cooling rate of 20–40 ℃ / min specified in this application is an optimized condition for the specific multilayer structure and self-detachment requirements of this application.

[0019] This application utilizes a three-layer structure of "silicon / high expansion coefficient transition layer / diamond thick film" to form a stress gradient, and combines a moderate cooling rate with laser cutting to remove the edge constraint, so that the thick film spontaneously detaches at a predetermined interface.

[0020] Preferably, the thickness of the transition layer is 200–1000 nm.

[0021] The transition layer provided by this invention is relatively thin, which can prevent large-area bonding between the substrate silicon and diamond while minimizing the impact of the transition layer on the warpage of the diamond thick film. Furthermore, very little transition layer material remains in the self-supporting diamond thick film after self-detachment, thus having minimal impact on the performance of the diamond thick film.

[0022] Preferably, a transition layer is deposited on a silicon substrate using magnetron sputtering, wherein the magnetron sputtering process parameters are: working pressure of 0.5–1.5 Pa, RF power of 80–200 W, silicon substrate temperature of 150–350 °C, and deposition time of 40–200 min.

[0023] Preferably, a diamond seed crystal layer is formed by spin coating, in which a diamond suspension is deposited layer by layer onto a transition layer. The first layer is deposited at a rotation speed of 800–1000 rpm for 10–30 s, and the second layer is deposited at a rotation speed of 1500–3000 rpm for 30–60 s.

[0024] The diamond seed layer provided by this invention serves to provide nucleation conditions (i.e., seeds) for the growth of thick diamond films. To ensure the uniformity of the seed layer thickness and the dispersion effect, nanoscale diamond particles are included in the diamond suspension.

[0025] Further optimization yields nanoscale diamond particles with an average particle size of 10-30 nm.

[0026] Preferably, the thickness of the diamond seed layer is 40-80 nm. By controlling the thickness of the diamond seed layer, this invention can facilitate the growth of thick diamond films while reducing the influence of the diamond seed layer on the warpage of the thick diamond film.

[0027] Preferably, a thick diamond film is deposited on the diamond seed layer using microwave plasma chemical vapor deposition (MPCVD). The process parameters for the microwave plasma chemical vapor deposition are as follows: the reaction atmosphere is a mixture of H2 and CH4, wherein the flow rate of CH4 accounts for 3-6%. The working pressure is 8-15 kPa, and the growth temperature is 850-900 ℃. The deposition time is 50–150 h.

[0028] This invention enables the efficient acquisition of high-quality diamond thick films of the desired thickness by controlling the concentration, pressure, temperature, and time of methane.

[0029] Preferably, the thickness of the diamond film is 50–150 μm.

[0030] Preferably, the laser cutting process parameters are: average power of 8-35 W, scanning speed of 5-15 mm / s, and cutting time of 10-60 s.

[0031] This invention, by controlling the aforementioned parameters, enables the laser to rapidly and penetratingly cut through thick diamond films without causing the films to crack due to excessive heat. Once the diamond edges have been cut, the thick diamond film can spontaneously peel off from the substrate, resulting in a complete, self-supporting thick diamond film.

[0032] Preferably, the silicon substrate is an intrinsic silicon wafer, which is a <100> oriented single-crystal silicon wafer with a size of 3-6 inches and a thickness of 3-5 mm.

[0033] Preferably, before depositing the transition layer on the silicon substrate, the silicon substrate is sequentially cleaned with anhydrous ethanol and deionized water, and then dried with nitrogen.

[0034] On the other hand, the present invention also provides a diamond film, which is prepared by the aforementioned method for preparing a peel-free, self-detaching diamond film.

[0035] Preferably, the diamond film has dimensions of Φ75–150 mm, a thickness of 50–150 μm, a self-peeling surface roughness Ra≤10 nm, a warpage ≤100 μm, and a Raman half-peak width ≤3 cm. -1 Thermal conductivity ≥ 1800 W / m·K.

[0036] The diamond film obtained by this invention has low surface roughness and excellent thermal conductivity, making it suitable for high-end thermal management and device packaging applications.

[0037] The diamond film provided by this invention possesses excellent comprehensive properties such as thermal conductivity, low warpage, and low surface roughness, and can be widely used in high-power semiconductor device packaging, RF power amplifier device heat dissipation substrates, laser thermal management components, precision optical windows, and high-end heat dissipation substrates. Furthermore, the preparation method is green and environmentally friendly, has good repeatability and reliability, and can be mass-produced, possessing significant potential for industrialization and economic value.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention uses a material with a higher coefficient of thermal expansion than both silicon substrate and diamond as a transition layer. By utilizing the high coefficient of thermal expansion of the transition layer and combining it with a suitable cooling rate, sufficient stress is transferred to the diamond during the cooling process, making it easier for the transition layer to detach from the silicon substrate. Furthermore, this invention uses the transition layer to separate the silicon substrate and diamond, preventing the silicon substrate and diamond from reacting over a large area to form strong chemical bonds that are not conducive to self-detachment without peeling. Attached Figure Description

[0039] Figure 1 This is a technical roadmap for preparing a peel-free, self-detaching diamond film provided in Examples 1–6 of the present invention.

[0040] Figure 2 Raman diagrams of the self-detaching large-size self-supporting diamond thin film materials provided in Examples 1-6 and Comparative Examples 1-3 of this invention.

[0041] Figure 3 The surface roughness diagrams are for the self-detaching large-size self-supporting diamond thin film materials provided in Examples 1-6 and Comparative Examples 1-3 of the present invention. Detailed Implementation

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0043] The term "embodiment" used herein, as an example, is not necessarily to be construed as superior to or better than other embodiments. Performance testing in the embodiments of this application, unless otherwise specified, employs conventional testing methods in the art. It should be understood that the terminology used in this application is merely for describing particular implementations and is not intended to limit the scope of this disclosure.

[0044] Unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; other experimental methods and technical means not specifically mentioned herein refer to experimental methods and technical means commonly used by one of ordinary skill in the art.

[0045] To better illustrate the content of this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented even without certain specific details. In the embodiments, some methods, means, instruments, and devices well-known to those skilled in the art are not described in detail in order to highlight the main points of this application.

[0046] Without conflict, the technical features disclosed in the embodiments of this application can be combined arbitrarily, and the resulting technical solution belongs to the content disclosed in the embodiments of this application.

[0047] To better understand the present invention, the following embodiments are provided for further detailed description of the present invention, but they should not be construed as limiting the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above-described invention are also considered to fall within the protection scope of the present invention.

[0048] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0049] Example 1: This embodiment provides a method for preparing a peel-free, self-detaching diamond film, such as... Figure 1 As shown, it includes: First, a 4-inch diameter, 4-mm thick monocrystalline silicon wafer with a <100> orientation was selected as the substrate. It was then ultrasonically cleaned sequentially with anhydrous ethanol and deionized water, followed by drying the substrate surface with high-purity nitrogen.

[0050] Next, a 500 nm AlN transition layer was deposited by magnetron sputtering with the following parameters: operating pressure: 0.5 Pa; RF power: 200 W; substrate temperature: 250 °C; time: 120 min. The resulting AlN transition layer had a thickness of 488 nm. The transition layer thickness provided in this embodiment helps to form a favorable stress gradient during the cooling stage, promoting film-substrate separation, and also helps to control the warpage of the thick diamond film.

[0051] Subsequently, two diamond seed crystal layers were spin-coated sequentially onto the substrate surface using a diamond suspension containing 30 nm nanoscale diamond particles: the first layer was spin-coated at 800 rpm for 30 s; the second layer was spin-coated at 1500 rpm for 60 s. The nanoscale diamond particles provided in this embodiment offer nucleation conditions (i.e., seeds) for the growth of the diamond thick film. To ensure the uniformity of the seed crystal thickness and its dispersion effect, the thickness of the diamond seed crystal layer was 80 nm. The thickness of the seed crystal layer provided in this embodiment is beneficial for the growth of the diamond thick film while also reducing the influence of the diamond seed crystal layer on the warpage of the diamond thick film.

[0052] After completing the diamond seed layer treatment, the treated substrate was placed in the MPCVD system, and the following process parameters were set for diamond film growth: gas ratio: H2:CH4 = 4%; working pressure: 12 kPa; growth temperature: 850 ℃; deposition time: 120 h.

[0053] Under the above conditions, a diamond thick film with a thickness of approximately 120 μm can be obtained. After the deposition process, the plasma source is turned off, and the sample temperature is controlled to drop at a cooling rate of 30 °C / min. The cooling rate provided in this embodiment enables the self-exfoliation of the diamond thick film and the transition layer.

[0054] During the cooling process, it was observed that the diamond thick film naturally and slowly detached from the silicon substrate. Subsequently, through-cut laser cutting was performed on the circumferential region of the sample: average power: 20 W; repetition rate: 10 kHz; scan speed: 10 mm / s; cutting time: 30 s. Understandably, since some diamond deposits at the edges during the diamond deposition process, forming an edging, this example solves the problem of the edging hindering self-peeling by using through-cut laser cutting to cut the diamond thick film to the transition layer. This allows for spontaneous peeling of the diamond thick film from the substrate, resulting in a complete, self-supporting diamond thick film. Furthermore, the diamond thick film does not crack due to excessive heat.

[0055] After cutting, the film spontaneously separates from the substrate, forming a complete, crack-free, self-supporting diamond film sample D1.

[0056] The performance of the obtained D1 sample was tested, and the results are as follows: Diamond film size: Φ100 mm, measured thickness 118 μm; Raman half-peak width (FWHM): 2.47 cm -1 ; Surface roughness (Ra) of the peeled surface: 6.91 nm; Film warpage: 83 μm; Thermal conductivity: 1813 W / m·K.

[0057] Example 2 First, a 6-inch diameter, 5 mm thick monocrystalline silicon wafer with a <100> orientation was selected as the substrate. It was then ultrasonically cleaned sequentially with anhydrous ethanol and deionized water, followed by drying the substrate surface with high-purity nitrogen gas.

[0058] Next, a Si3N4 transition layer of approximately 300 nm was deposited by magnetron sputtering with the following parameters: operating pressure: 1.5 Pa; RF power: 120 W; substrate temperature: 300 ℃; time: 90 min. The resulting Si3N4 transition layer had a thickness of 293 nm. The transition layer thickness provided in this embodiment helps to form a favorable stress gradient during the cooling stage, promoting film-substrate separation, and also helps to control the warpage of the diamond thick film.

[0059] Subsequently, two diamond seed crystal layers were spin-coated sequentially onto the substrate surface using a diamond suspension containing 20 nm nanoscale diamond particles: the first layer was spin-coated at 900 rpm for 20 s; the second layer was spin-coated at 2300 rpm for 40 s. The nanoscale diamond particles provided in this embodiment offer nucleation conditions (i.e., seeds) for the growth of the diamond thick film. To ensure the uniformity of the seed crystal thickness and its dispersion effect, the thickness of the diamond seed crystal layer was 60 nm. The thickness of the seed crystal layer provided in this embodiment is beneficial for the growth of the diamond thick film while also reducing the influence of the diamond seed crystal layer on the warpage of the diamond thick film.

[0060] After the seed layer treatment is completed, the treated substrate is placed in the MPCVD system and the following process parameters are set for diamond film growth: gas ratio: H2:CH4 = 3%; working pressure: 10 kPa; growth temperature: 870 ℃; deposition time: 150 h.

[0061] Under the above conditions, a diamond thick film with a thickness of approximately 150 μm can be obtained. After the deposition process, the plasma source is turned off, and the sample temperature is controlled to drop at a cooling rate of 20 °C / min. The cooling rate provided in this embodiment enables the diamond thick film and the transition layer to self-exfoliate.

[0062] During the cooling process, it was observed that the diamond film naturally and slowly detached from the silicon substrate. Subsequently, a through-cut was performed on the circumferential region of the sample: average power: 25 W; repetition rate: 10 kHz; scan speed: 12 mm / s; cutting time: 45 s. Since some diamond deposits at the edges during the diamond deposition process, forming an edging, this example solved the problem of the edging hindering self-peeling by using laser cutting to cut the diamond thick film to the transition layer. This allows for spontaneous peeling of the diamond thick film from the substrate, resulting in a complete, self-supporting diamond thick film. Furthermore, the diamond thick film does not crack due to excessive heat.

[0063] After cutting, the film spontaneously separates from the substrate, forming a complete, crack-free, self-supporting diamond film sample D2.

[0064] The performance of the obtained D2 sample was tested, and the results are as follows: Diamond film size: Φ150 mm, measured thickness: 147 μm; Raman half-peak width (FWHM): 2.33 cm -1 ; Surface roughness (Ra) of the peeled surface: 5.71 nm; Film warpage: 88 μm; Thermal conductivity: 1874 W / m·K.

[0065] Example 3: First, a 3-inch diameter, 3-mm thick monocrystalline silicon wafer with a <100> orientation was selected as the substrate. It was then ultrasonically cleaned sequentially with anhydrous ethanol and deionized water, followed by drying the substrate surface with high-purity nitrogen.

[0066] Next, a SiC transition layer of approximately 800 nm was deposited by magnetron sputtering with the following parameters: operating pressure: 1.0 Pa; RF power: 80 W; substrate temperature: 200 °C; time: 180 min. The resulting SiC transition layer thickness was 785 nm. The transition layer thickness provided in this embodiment helps to form a favorable stress gradient during the cooling stage, promoting film-substrate separation, and also helps to control the warpage of the thick diamond film.

[0067] Subsequently, two diamond seed layers were spin-coated sequentially onto the SiC transition layer surface using a diamond suspension containing 10 nm nanoscale diamond particles: the first layer was spin-coated at 1000 rpm for 30 s; the second layer was spin-coated at 3000 rpm for 30 s. The nanoscale diamond particles provided in this embodiment offer nucleation conditions (i.e., seeds) for the growth of the diamond thick film. To ensure the uniformity of the seed layer thickness and its dispersion effect, the thickness of this diamond seed layer is 40 nm. The thickness of the seed layer provided in this embodiment is beneficial for the growth of the diamond thick film while also reducing the influence of the diamond seed layer on the warpage of the diamond thick film.

[0068] After the seed layer treatment is completed, the treated substrate is placed in the MPCVD system and the following process parameters are set for diamond film growth: gas ratio: H2:CH4 = 6%; working pressure: 15 kPa; growth temperature: 900 ℃; deposition time: 50 h.

[0069] Under the above conditions, a diamond thick film with a thickness of approximately 50 μm can be obtained. After the deposition process, the plasma source is turned off, and the sample temperature is controlled to drop at a cooling rate of 40 °C / min. The cooling rate provided in this embodiment enables the self-exfoliation of the diamond thick film and the transition layer.

[0070] During the cooling process, it was observed that the diamond thick film naturally and slowly detached from the silicon substrate. Subsequently, a through-cut was performed on the circumferential region of the sample: average power: 30 W; repetition rate: 10 kHz; scan speed: 8 mm / s; cutting time: 20 s. Understandably, since some diamond deposits at the edges during the diamond deposition process, forming an edge, this example solves the problem of the edge binding the self-peeling by using laser cutting to cut the diamond thick film to the transition layer. This allows for spontaneous peeling of the diamond thick film from the substrate, resulting in a complete, self-supporting diamond thick film. Furthermore, the diamond thick film does not crack due to excessive heat.

[0071] After cutting, the film spontaneously separates from the substrate, forming a complete, crack-free, self-supporting diamond film sample D3.

[0072] The performance of the obtained D3 sample was tested, and the results are as follows: Diamond film size: Φ75 mm, measured thickness: 52 μm; Raman half-peak width (FWHM): 2.69 cm -1 ; Surface roughness (Ra) of the peeled surface: 5.78 nm; Film warpage: 73 μm; Thermal conductivity: 1932 W / m·K.

[0073] Example 4 This embodiment provides a method for preparing a peel-free, self-detaching diamond film, comprising: First, a 4-inch diameter, 4-mm thick monocrystalline silicon wafer with a <100> orientation was selected as the substrate. It was then ultrasonically cleaned sequentially with anhydrous ethanol and deionized water, followed by drying the substrate surface with high-purity nitrogen.

[0074] A 500 nm Al₂O₃ transition layer was deposited by magnetron sputtering with the following parameters: working pressure: 0.5 Pa; RF power: 200 W; substrate temperature: 250 ℃; time: 120 min. The resulting Al₂O₃ transition layer had a thickness of 512 nm.

[0075] Subsequently, two diamond seed crystal layers were spin-coated sequentially onto the substrate surface using a diamond suspension containing 30 nm nanoscale diamond particles: the first layer was spin-coated at 800 rpm for 30 s; the second layer was spin-coated at 1500 rpm for 60 s. The nanoscale diamond particles provided in this embodiment offer nucleation conditions (i.e., seeds) for the growth of the diamond thick film. To ensure the uniformity of the seed crystal thickness and its dispersion effect, the thickness of the diamond seed crystal layer was 80 nm. The thickness of the seed crystal layer provided in this embodiment is beneficial for the growth of the diamond thick film while also reducing the influence of the diamond seed crystal layer on the warpage of the diamond thick film.

[0076] After completing the diamond seed layer treatment, the treated substrate was placed in the MPCVD system, and the following process parameters were set for diamond film growth: gas ratio: H2:CH4 = 4%; working pressure: 12 kPa; growth temperature: 850 ℃; deposition time: 120 h.

[0077] Under the above conditions, a diamond thick film with a thickness of approximately 120 μm can be obtained. After the deposition process, the plasma source is turned off, and the sample temperature is controlled to drop at a cooling rate of 30 °C / min. The cooling rate provided in this embodiment enables the self-exfoliation of the diamond thick film and the transition layer.

[0078] During the cooling process, it was observed that the diamond thick film naturally and slowly detached from the silicon substrate. Subsequently, through-cut laser cutting was performed on the circumferential region of the sample: average power: 20 W; repetition rate: 10 kHz; scan speed: 10 mm / s; cutting time: 30 s. Understandably, since some diamond deposits at the edges during the diamond deposition process, forming an edging, this example solves the problem of the edging hindering self-peeling by using through-cut laser cutting to cut the diamond thick film to the transition layer. This allows for spontaneous peeling of the diamond thick film from the substrate, resulting in a complete, self-supporting diamond thick film. Furthermore, the diamond thick film does not crack due to excessive heat.

[0079] After cutting, the film spontaneously separated from the substrate, forming a complete, crack-free, self-supporting diamond film sample D4.

[0080] The difference between this embodiment and Embodiment 1 is that a 500 nm Al2O3 transition layer was deposited by magnetron sputtering, with the following parameters: working pressure: 0.5 Pa; RF power: 200 W; substrate temperature: 250 ℃; time: 120 min. The thickness of the Al2O3 transition layer obtained was 512 nm.

[0081] The performance of the obtained D4 sample was tested, and the results are as follows: Diamond film size: Φ100 mm, measured thickness 123 μm; Raman half-peak width (FWHM): 2.71 cm -1 ; Surface roughness (Ra) of the peeled surface: 6.73 nm; Film warpage: 94 μm; Thermal conductivity: 1816 W / m·K.

[0082] Example 5 First, a 6-inch diameter, 5 mm thick monocrystalline silicon wafer with a <100> orientation was selected as the substrate. It was then ultrasonically cleaned sequentially with anhydrous ethanol and deionized water, followed by drying the substrate surface with high-purity nitrogen gas.

[0083] Next, a Si3N4 transition layer of approximately 180 nm was deposited by magnetron sputtering with the following parameters: working pressure: 1.5 Pa; RF power: 120 W; substrate temperature: 300 ℃; time: 55 min. The thickness of the obtained Si3N4 transition layer was 192 nm.

[0084] Subsequently, two diamond seed crystal layers were spin-coated sequentially onto the substrate surface using a diamond suspension containing 20 nm nanoscale diamond particles: the first layer was spin-coated at 900 rpm for 20 s; the second layer was spin-coated at 2300 rpm for 40 s. The nanoscale diamond particles provided in this embodiment offer nucleation conditions (i.e., seeds) for the growth of the diamond thick film. To ensure the uniformity of the seed crystal thickness and its dispersion effect, the thickness of the diamond seed crystal layer was 60 nm. The thickness of the seed crystal layer provided in this embodiment is beneficial for the growth of the diamond thick film while also reducing the influence of the diamond seed crystal layer on the warpage of the diamond thick film.

[0085] After the seed layer treatment is completed, the treated substrate is placed in the MPCVD system and the following process parameters are set for diamond film growth: gas ratio: H2:CH4 = 3%; working pressure: 10 kPa; growth temperature: 870 ℃; deposition time: 150 h.

[0086] Under the above conditions, a diamond thick film with a thickness of approximately 150 μm can be obtained. After the deposition process, the plasma source is turned off, and the sample temperature is controlled to drop at a cooling rate of 20 °C / min. The cooling rate provided in this embodiment enables the diamond thick film and the transition layer to self-exfoliate.

[0087] During the cooling process, it was observed that the diamond film naturally and slowly detached from the silicon substrate. Subsequently, a through-cut was performed on the circumferential region of the sample: average power: 25 W; repetition rate: 10 kHz; scan speed: 12 mm / s; cutting time: 45 s. Since some diamond deposits at the edges during the diamond deposition process, forming an edging, this example solved the problem of the edging hindering self-peeling by using laser cutting to cut the diamond thick film to the transition layer. This allows for spontaneous peeling of the diamond thick film from the substrate, resulting in a complete, self-supporting diamond thick film. Furthermore, the diamond thick film does not crack due to excessive heat.

[0088] After cutting, the film spontaneously separates from the substrate, forming a complete, crack-free, self-supporting diamond film sample D5.

[0089] The difference between this embodiment and Embodiment 2 is that a Si3N4 transition layer of approximately 180 nm was deposited using magnetron sputtering, with the following parameters: working pressure: 1.5 Pa; RF power: 120 W; substrate temperature: 300 ℃; time: 55 min. The resulting Si3N4 transition layer had a thickness of 192 nm.

[0090] The performance of the obtained D5 sample was tested, and the results are as follows: Diamond film size: Φ150 mm, measured thickness: 147 μm; Raman half-peak width (FWHM): 2.74 cm -1 ; Surface roughness (Ra) of the peeled surface: 6.01 nm; Film warpage: 99 μm; Thermal conductivity: 1855 W / m·K.

[0091] Example 6 First, a 3-inch diameter, 3-mm thick monocrystalline silicon wafer with a <100> orientation was selected as the substrate. It was then ultrasonically cleaned sequentially with anhydrous ethanol and deionized water, followed by drying the substrate surface with high-purity nitrogen.

[0092] Next, a SiC transition layer of approximately 1100 nm was deposited by magnetron sputtering with the following parameters: working pressure: 1.0 Pa; RF power: 80 W; substrate temperature: 200 ℃; time: 210 min. The thickness of the SiC transition layer was 1088 nm.

[0093] Subsequently, two diamond seed layers were spin-coated sequentially onto the SiC transition layer surface using a diamond suspension containing 10 nm nanoscale diamond particles: the first layer was spin-coated at 1000 rpm for 30 s; the second layer was spin-coated at 3000 rpm for 30 s. The nanoscale diamond particles provided in this embodiment offer nucleation conditions (i.e., seeds) for the growth of the diamond thick film. To ensure the uniformity of the seed layer thickness and its dispersion effect, the thickness of this diamond seed layer is 40 nm. The thickness of the seed layer provided in this embodiment is beneficial for the growth of the diamond thick film while also reducing the influence of the diamond seed layer on the warpage of the diamond thick film.

[0094] After the seed layer treatment is completed, the treated substrate is placed in the MPCVD system and the following process parameters are set for diamond film growth: gas ratio: H2:CH4 = 6%; working pressure: 15 kPa; growth temperature: 900 ℃; deposition time: 50 h.

[0095] Under the above conditions, a diamond thick film with a thickness of approximately 50 μm can be obtained. After the deposition process, the plasma source is turned off, and the sample temperature is controlled to drop at a cooling rate of 40 °C / min. The cooling rate provided in this embodiment enables the self-exfoliation of the diamond thick film and the transition layer.

[0096] During the cooling process, it was observed that the diamond thick film naturally and slowly detached from the silicon substrate. Subsequently, a through-cut was performed on the circumferential region of the sample: average power: 30 W; repetition rate: 10 kHz; scan speed: 8 mm / s; cutting time: 20 s. Understandably, since some diamond deposits at the edges during the diamond deposition process, forming an edge, this example solves the problem of the edge binding the self-peeling by using laser cutting to cut the diamond thick film to the transition layer. This allows for spontaneous peeling of the diamond thick film from the substrate, resulting in a complete, self-supporting diamond thick film. Furthermore, the diamond thick film does not crack due to excessive heat.

[0097] After cutting, the film spontaneously separates from the substrate, forming a complete, crack-free, self-supporting diamond film sample D6.

[0098] Unlike Example 3, a SiC transition layer of approximately 1100 nm was deposited using magnetron sputtering with the following parameters: operating pressure: 1.0 Pa; RF power: 80 W; substrate temperature: 200 °C; time: 210 min. The resulting SiC transition layer had a thickness of 1088 nm.

[0099] The performance of the obtained D6 sample was tested, and the results are as follows: Diamond film size: Φ75 mm, measured thickness: 54 μm; Raman half-peak width (FWHM): 2.70 cm -1 ; Surface roughness (Ra) of the peeled surface: 5.91 nm; Film warpage: 91 μm; Thermal conductivity: 1873 W / m·K.

[0100] Comparative Example 1: First, a 3-inch diameter, 3-mm thick monocrystalline silicon wafer with a <100> orientation was selected as the substrate. It was then ultrasonically cleaned sequentially with anhydrous ethanol and deionized water, followed by drying the substrate surface with high-purity nitrogen.

[0101] Two diamond seed layers were sequentially spin-coated onto the surface of a single-crystal silicon wafer using a diamond suspension containing 10 nm nanoscale diamond particles: the first layer was spin-coated at 1000 rpm for 30 s, and the second layer at 3000 rpm for 30 s. The nanoscale diamond particles provided in this comparative example provide nucleation conditions (i.e., seeds) for the growth of the diamond thick film. To ensure the uniformity of the seed layer thickness and its dispersion effect, the thickness of this diamond seed layer was 40 nm. The thickness of the seed layer provided in this comparative example is beneficial for the growth of the diamond thick film while also reducing the influence of the diamond seed layer on the warpage of the diamond thick film.

[0102] After the seed layer treatment is completed, the treated substrate is placed in the MPCVD system and the following process parameters are set for diamond film growth: gas ratio: H2:CH4 = 6%; working pressure: 15 kPa; growth temperature: 900 ℃; deposition time: 50 h.

[0103] Under the above conditions, a diamond film with a thickness of approximately 50 μm can be obtained. After the deposition process is completed, the plasma source is turned off, and the sample temperature is controlled to drop at a cooling rate of 40 °C / min.

[0104] During the cooling process, it was observed that the diamond film did not slowly detach from the silicon substrate. Subsequently, through the etching process of the silicon substrate, a complete and crack-free self-supporting diamond film sample S1 was obtained.

[0105] Compared with Example 3, this comparative example does not have a deposited transition layer. After the diamond edge is cut, the diamond thick film does not spontaneously peel off from the substrate. This is because the diamond and silicon substrate are tightly bonded and cannot achieve self-peeling. Subsequently, through the etching process of the silicon substrate, a complete and crack-free self-supporting diamond film sample S1 is obtained.

[0106] The performance of the obtained S1 sample was tested, and the results are as follows: Diamond film size: Φ75 mm, measured thickness: 54 μm; Raman half-peak width (FWHM): 2.77 cm -1 ; Surface roughness (Ra) of the peeled surface: 6.37 nm; Film warpage: 189 μm; Thermal conductivity: 1865 W / m·K.

[0107] Comparative Example 2: First, a 3-inch diameter, 3-mm thick monocrystalline silicon wafer with a <100> orientation was selected as the substrate. It was then ultrasonically cleaned sequentially with anhydrous ethanol and deionized water, followed by drying the substrate surface with high-purity nitrogen.

[0108] Next, a 500 nm thick SiO2 transition layer (a material with an ultra-low coefficient of thermal expansion) was deposited by magnetron sputtering with the following parameters: working pressure: 1.0 Pa; RF power: 80 W; substrate temperature: 200 ℃; time: 180 min. The resulting SiO2 transition layer had a thickness of 785 nm.

[0109] Subsequently, two diamond seed layers were spin-coated sequentially onto the SiC transition layer surface using a diamond suspension containing 10 nm nanoscale diamond particles: the first layer was spin-coated at 1000 rpm for 30 s; the second layer was spin-coated at 3000 rpm for 30 s. The nanoscale diamond particles provided in this embodiment offer nucleation conditions (i.e., seeds) for the growth of the diamond thick film. To ensure the uniformity of the seed layer thickness and its dispersion effect, the thickness of this diamond seed layer is 40 nm. The thickness of the seed layer provided in this embodiment is beneficial for the growth of the diamond thick film while also reducing the influence of the diamond seed layer on the warpage of the diamond thick film.

[0110] After the seed layer treatment is completed, the treated substrate is placed in the MPCVD system and the following process parameters are set for diamond film growth: gas ratio: H2:CH4 = 6%; working pressure: 15 kPa; growth temperature: 900 ℃; deposition time: 50 h.

[0111] Under the above conditions, a diamond film with a thickness of approximately 50 μm can be obtained. After the deposition process is completed, the plasma source is turned off, and the sample temperature is controlled to drop at a cooling rate of 40 °C / min.

[0112] During the cooling process, it was observed that the diamond thick film did not slowly detach from the silicon substrate. Subsequently, a through-cut was performed on the circumferential region of the sample: average power: 30 W; repetition frequency: 10 kHz; scan speed: 8 mm / s; cutting time: 20 s.

[0113] Compared with Example 3, the difference is that a 500 nm thick SiO2 transition layer (a material with an ultra-low coefficient of expansion) was deposited by magnetron sputtering. After the diamond edge was cut, the stress could not be transferred to the diamond surface because the material of the transition layer has an ultra-low coefficient of expansion. Therefore, the spontaneous separation of the diamond film from the substrate was not achieved. Subsequently, a complete and crack-free self-supporting diamond film sample S2 was obtained by etching the silicon substrate.

[0114] The performance of the obtained S2 sample was tested, and the results are as follows: Diamond film size: Φ75mm, measured thickness: 58μm; Raman half-peak width (FWHM): 2.74 cm -1 ; Surface roughness (Ra) of the peeled surface: 8.39 nm; Film warpage: 167 μm; Thermal conductivity: 1858 W / m·K.

[0115] Comparative Example 3: First, a 3-inch diameter, 3-mm thick monocrystalline silicon wafer with a <100> orientation was selected as the substrate. It was then ultrasonically cleaned sequentially with anhydrous ethanol and deionized water, followed by drying the substrate surface with high-purity nitrogen.

[0116] Next, a SiC transition layer of approximately 800 nm was deposited by magnetron sputtering with the following parameters: operating pressure: 1.0 Pa; RF power: 80 W; substrate temperature: 200 °C; time: 180 min. The resulting SiC transition layer thickness was 785 nm. The transition layer thickness provided in this embodiment helps to form a favorable stress gradient during the cooling stage, promoting film-substrate separation, and also helps to control the warpage of the thick diamond film.

[0117] Subsequently, two diamond seed layers were spin-coated sequentially onto the SiC transition layer surface using a diamond suspension containing 10 nm nanoscale diamond particles: the first layer was spin-coated at 1000 rpm for 30 s; the second layer was spin-coated at 3000 rpm for 30 s. The nanoscale diamond particles provided in this embodiment offer nucleation conditions (i.e., seeds) for the growth of the diamond thick film. To ensure the uniformity of the seed layer thickness and its dispersion effect, the thickness of this diamond seed layer is 40 nm. The thickness of the seed layer provided in this embodiment is beneficial for the growth of the diamond thick film while also reducing the influence of the diamond seed layer on the warpage of the diamond thick film.

[0118] After the seed layer treatment is completed, the treated substrate is placed in the MPCVD system and the following process parameters are set for diamond film growth: gas ratio: H2:CH4 = 6%; working pressure: 15 kPa; growth temperature: 900 ℃; deposition time: 50 h.

[0119] Under the above conditions, a diamond film with a thickness of approximately 50 μm can be obtained. After the deposition process is completed, the plasma source is turned off, and the sample temperature is controlled to drop at a cooling rate of 10 °C / min.

[0120] During the cooling process, it was observed that the diamond film did not slowly detach from the silicon substrate. Subsequently, hydrofluoric acid was used to etch and remove the silicon substrate for 24 hours, resulting in a complete, crack-free self-supporting diamond film sample S3.

[0121] Compared to Example 3, only the cooling rate was changed to 10 °C / min, while other parameters remained the same. After the diamond edge was cut, spontaneous separation of the diamond film from the substrate was not achieved. Subsequently, hydrofluoric acid was used to etch and remove the silicon substrate for 24 hours, resulting in a complete, crack-free self-supporting diamond film sample S3.

[0122] The performance of the obtained S3 sample was tested, and the results are as follows: Diamond film size: Φ75 mm, measured thickness: 58 μm; Raman half-peak width (FWHM): 2.62 cm -1 ; Surface roughness (Ra) of the peeled surface: 6.28 nm; Film warpage: 81 μm; Thermal conductivity: 1927 W / m·K.

[0123] Comparative Example 4 First, a 3-inch diameter, 3-mm thick monocrystalline silicon wafer with a <100> orientation was selected as the substrate. It was then ultrasonically cleaned sequentially with anhydrous ethanol and deionized water, followed by drying the substrate surface with high-purity nitrogen.

[0124] Next, a SiC transition layer of approximately 800 nm was deposited by magnetron sputtering with the following parameters: operating pressure: 1.0 Pa; RF power: 80 W; substrate temperature: 200 °C; time: 180 min. The resulting SiC transition layer thickness was 785 nm. The transition layer thickness provided in this embodiment helps to form a favorable stress gradient during the cooling stage, promoting film-substrate separation, and also helps to control the warpage of the thick diamond film.

[0125] Subsequently, two diamond seed layers were spin-coated sequentially onto the SiC transition layer surface using a diamond suspension containing 10 nm nanoscale diamond particles: the first layer was spin-coated at 1000 rpm for 30 s; the second layer was spin-coated at 3000 rpm for 30 s. The nanoscale diamond particles provided in this embodiment offer nucleation conditions (i.e., seeds) for the growth of the diamond thick film. To ensure the uniformity of the seed layer thickness and its dispersion effect, the thickness of this diamond seed layer is 40 nm. The thickness of the seed layer provided in this embodiment is beneficial for the growth of the diamond thick film while also reducing the influence of the diamond seed layer on the warpage of the diamond thick film.

[0126] After the seed layer treatment is completed, the treated substrate is placed in the MPCVD system and the following process parameters are set for diamond film growth: gas ratio: H2:CH4 = 6%; working pressure: 15 kPa; growth temperature: 900 ℃; deposition time: 50 h.

[0127] Under the above conditions, a diamond film with a thickness of approximately 50 μm can be obtained. After the deposition process, the plasma source is turned off, and the sample temperature is controlled to drop at a cooling rate of 50 °C / min. The diamond film provided in this embodiment cracked directly.

[0128] Compared to Example 3, only the cooling rate was changed to 50 °C / min, while all other parameters remained the same. During the cooling process, the diamond film cracked directly.

[0129] Comparative Example 5 First, a 3-inch diameter, 3-mm thick monocrystalline silicon wafer with a <100> orientation was selected as the substrate. It was then ultrasonically cleaned sequentially with anhydrous ethanol and deionized water, followed by drying the substrate surface with high-purity nitrogen.

[0130] Next, a SiC transition layer of approximately 800 nm was deposited by magnetron sputtering with the following parameters: operating pressure: 1.0 Pa; RF power: 80 W; substrate temperature: 200 °C; time: 180 min. The resulting SiC transition layer thickness was 785 nm. The transition layer thickness provided in this embodiment helps to form a favorable stress gradient during the cooling stage, promoting film-substrate separation, and also helps to control the warpage of the thick diamond film.

[0131] Subsequently, two diamond seed layers were spin-coated sequentially onto the SiC transition layer surface using a diamond suspension containing 10 nm nanoscale diamond particles: the first layer was spin-coated at 1000 rpm for 30 s; the second layer was spin-coated at 3000 rpm for 30 s. The nanoscale diamond particles provided in this embodiment offer nucleation conditions (i.e., seeds) for the growth of the diamond thick film. To ensure the uniformity of the seed layer thickness and its dispersion effect, the thickness of this diamond seed layer is 40 nm. The thickness of the seed layer provided in this embodiment is beneficial for the growth of the diamond thick film while also reducing the influence of the diamond seed layer on the warpage of the diamond thick film.

[0132] After the seed layer treatment is completed, the treated substrate is placed in the MPCVD system and the following process parameters are set for diamond film growth: gas ratio: H2:CH4 = 6%; working pressure: 15 kPa; growth temperature: 900 ℃; deposition time: 50 h.

[0133] Under the above conditions, a diamond film with a thickness of approximately 50 μm can be obtained. After the deposition process is completed, the plasma source is turned off, and the sample temperature is controlled to drop at a cooling rate of 40 °C / min.

[0134] Compared to Example 3, the diamond thick film edge was not cut with a laser, and the diamond thick film was not peeled off from the substrate.

[0135] Performance Analysis This invention discloses a diamond thick film and its preparation method, achieving a large-size, smooth-surfaced, low-warpage, high-thermal-conductivity, peel-free, and self-detachable self-supporting diamond material. The performance testing methods for the diamond thick film samples prepared in this invention are as follows: dimensions were measured according to national standard GB / T 21389-2008, with decimal places removed, retaining only integers; surface roughness was tested according to national standard GB / T 32189-2015; warpage was tested according to national standard GB / T 32280-2022; Raman full width at half maximum (FWHM) was measured according to national standard GB / T 33252-2016; and thermal conductivity was tested according to national standard GB / T 22588-2008. Specific test results are as follows: Figure 2 As shown in ‒3 and Tables 1‒2.

[0136] Figure 3 The self-peeling surface roughness test results shown indicate that the peel-free self-detachment process of the present invention can obtain a smooth interface with Ra≤10 nm. Figure 2 Raman spectroscopy confirmed that the embodiments of the present invention, while achieving self-detachment and low warpage, still maintained a high-quality diamond structure with narrow full width at half maximum (FWHM) and high phase purity. As shown in Table 1, under the conditions of using a high thermal expansion coefficient transition layer and controlling the cooling rate at 20–40 ℃ / min, the warpage of the large-size self-supporting diamond thick films obtained in Examples 1–6 of the present invention was ≤100 μm; while in Comparative Examples 1–3, although self-supporting diamond films could also be obtained, the warpage was significantly increased or they could not detach on their own. The thermal conductivity data in Table 2 show that the thermal conductivity of the diamond thick films prepared by the present invention reached or exceeded 1800 W / m·K, achieving a unity of low warpage, high thermal conductivity, and self-detachment without mechanical / chemical peeling, thereby effectively solving the problems of difficult peeling, large warpage, complex processes, and serious pollution in the prior art of diamond thick films.

[0137] As can be seen from the case studies, the large-size diamond thick films prepared by Examples 1 to 6 of this invention have good performance, simple preparation process, and low cost. Compared with the comparative examples, they have low warpage and can achieve self-detachment, which provides important technical support for their wide application in semiconductor chip substrates and other fields.

[0138] Table 1 shows the warpage of the self-detaching large-size self-supporting diamond film materials provided by the present invention and comparative examples.

[0139] Table 2 Thermal conductivity of the self-detaching large-size self-supporting diamond thin film materials provided by the present invention and comparative examples

[0140] Furthermore, the terms "first," "second," etc., used in the above terms are only used to distinguish the objects described and have no sequential or technical meaning, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0141] In the description of this invention, unless otherwise stated, "a plurality of" means two or more, unless otherwise expressly defined.

[0142] Of course, the above description is only a specific embodiment of the present invention and is not intended to limit the scope of the present invention. All equivalent changes or modifications made to the structure, features and principles described in the claims of the present invention should be included in the scope of the claims of the present invention.

[0143] The above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and are not intended to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for producing a self-releasing diamond film without peeling, characterized by, Comprising: depositing a transition layer on the silicon substrate, the material of the transition layer having a thermal expansion coefficient higher than that of the silicon substrate and diamond; depositing a diamond seed layer on the transition layer, depositing a diamond thick film on the diamond seed layer, and performing cooling after the deposition is completed, the cooling rate being 20-40 ℃ / min; cutting the edge of the diamond thick film using a laser to make the diamond thick film self-detach to obtain a self-supporting diamond thick film.

2. The method of claim 1, wherein the method is characterized by: The material of the transition layer is aluminum oxide, aluminum nitride, silicon nitride, or silicon carbide.

3. The method of claim 2, wherein the method further comprises: The material of the transition layer is aluminum nitride, silicon nitride, or silicon carbide.

4. The method of claim 1, wherein the method is characterized by: The thickness of the transition layer is 200-1000 nm.

5. The method of claim 1, wherein the diamond film is prepared by a method comprising: The transition layer is deposited on the silicon substrate using a magnetron sputtering method, and the process parameters of the magnetron sputtering are as follows: the working pressure is 0.5-1.5 Pa, the radio frequency power is 80-200 W, the silicon substrate temperature is 150-350 ℃, and the deposition time is 40-200 min.

6. The method of claim 1, wherein the diamond film is prepared by a method comprising: The diamond suspension is deposited on the transition layer layer by layer using a spin coating method, wherein the rotation speed for the first layer deposition is 800-1000 rpm, and the time is 10-30 s; the rotation speed for the second layer deposition is 1500-3000 rpm, and the time is 30-60 s.

7. The method of claim 6, wherein the diamond film is prepared by a method comprising: The diamond suspension contains nanoscale diamond particles.

8. The method of claim 7, wherein the diamond film is prepared by a method comprising: The average particle size of the nanoscale diamond particles is 10-30 nm.

9. The method of claim 1, wherein the diamond film is prepared by a method comprising: The thickness of the diamond seed layer is 40-80 nm.

10. The method of claim 1, wherein the diamond film is prepared by a method comprising: The diamond thick film is deposited on the diamond seed layer using a microwave plasma chemical vapor deposition method, and the process parameters of the microwave plasma chemical vapor deposition are as follows: the reaction atmosphere is a mixed gas of H2 and CH4, wherein the flow rate of CH4 accounts for 3-6%; The working pressure is 8-15 kPa, and the growth temperature is 850-900 ℃; The deposition time is 50-150 h.

11. The method of claim 1, wherein the diamond film is prepared by a method comprising: The thickness of the diamond thick film is 50-150 μm.

12. The method of claim 1, wherein the diamond film is prepared by a method comprising: The silicon substrate is an intrinsic silicon wafer, which is a <100> oriented single crystal silicon wafer, a wafer with a size of 3-6 inches, and a thickness of 3-5 mm.

13. The method of claim 1, wherein the diamond film is prepared by a method comprising: Before depositing the transition layer on the silicon substrate, the silicon substrate is subjected to surface cleaning with anhydrous ethanol and deionized water in sequence, and then subjected to nitrogen drying treatment.

14. The method of claim 1, wherein the diamond film is prepared by a method comprising: The process parameters of the laser cutting are as follows: the average power is 8-35 W, the scanning speed is 5-15 mm / s, and the cutting time is 10-60 s.

15. A diamond film, characterized in that, Prepared by the preparation method of the self-detached diamond film without stripping according to any one of claims 1-14.

16. The diamond film of claim 15, wherein, The size of the diamond film is Φ75-150 mm, the thickness is 50-150 μm, the self-stripping surface roughness Ra≤10 nm, the warping degree ≤100 μm, the Raman half-peak width ≤3 cm -1 , and the thermal conductivity ≥1800 W / m·K.

17. The diamond film according to claim 15 or 16 is applied on high-power semiconductor device packaging, radio frequency power amplifier device heat dissipation substrate, laser thermal management component, precision optical window, and high-end heat dissipation substrate.

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