A method for preparing a diamond microchannel heat sink with high thermal conductivity and low fluid resistance

Abstract

The invention discloses a method for preparing a high thermal conductivity and low fluid resistance diamond microchannel heat sink, firstly, a dielectric layer film is deposited on the surface of a cleaned polished single crystal silicon wafer substrate, a groove structure with a microchannel frame is formed on the surface of the dielectric layer film by etching using a mask plate with microchannel gate holes; diamond polycrystalline film is epitaxially grown multiple times on the surface of the dielectric layer film with the groove structure, the groove is filled and the dielectric film is covered, and the growth surface of the diamond polycrystalline film is thinned and polished to be flat; the single crystal silicon wafer substrate and the dielectric layer film are removed by pickling or etching, and the nucleation layer of the diamond polycrystalline film is treated by plasma active etching to obtain a diamond wafer with a microchannel structure; finally, a layer of super-hydrophobic amorphous carbon film is deposited on the surface of the diamond microchannel, thereby obtaining a diamond microchannel heat sink with high thermal conductivity and low fluid resistance. The invention comprehensively utilizes the advantages of high thermal conductivity of diamond and super-hydrophobic amorphous carbon-based film, and has significant significance for improving the heat dissipation performance of high-power semiconductor lasers and large-scale integrated circuits.

Description

Technical Field

[0001] The invention relates to a method for preparing a diamond microchannel heat sink with high thermal conductivity and low fluid resistance, and belongs to the technical field of semiconductor materials. Background Art

[0002] With the development of the semiconductor chip industry, a larger portion of the power of ultra-large-scale integrated circuits, semiconductor lasers, and other high-power optical / electronic devices and equipment will be converted into waste heat during operation. The resulting temperature rise seriously affects their working efficiency, reliability, and lifespan, which puts forward more stringent requirements on the heat dissipation capacity of their heat sinks and packaging materials. At present, the application capacity of traditional power device heat dissipation technology in terms of architecture system and process is still limited to 400 W / cm 2 The heat flux density of high-power devices is much lower than that of normal operation (1 KW / cm 2 ), even the heat flux density of local hot spots can reach 5 KW / cm 2 , the problem of efficient heat dissipation has become a technical bottleneck in the application of power devices.

[0003] Microchannel cooling is currently the most commonly used effective heat dissipation method, which can efficiently dissipate heat flux density. Its core part is the micro-groove with a high aspect ratio, which can dissipate a large amount of heat in a small volume to meet the temperature control requirements. In order to effectively improve the heat dissipation performance of the device, the semiconductor industry often uses embedded microchannel structures to increase the specific surface area of ​​Si (thermal conductivity is 83 W / m·K) or Cu (thermal conductivity is 550 W / m·K) in contact with the cooling fluid to achieve faster heat conduction. However, due to the thermal and corrosion resistance of the substrate heat dissipation materials such as Si and Cu, this type of heat sink material cannot meet the heat dissipation and application requirements of high-power devices. Therefore, finding a heat sink material with higher thermal conductivity becomes the key. CVD diamond has a thermal conductivity of up to 1800 W / m·K, good insulation, stable physical and chemical properties, and can quickly remove heat from devices. It is an important material for efficient heat dissipation devices (Electronic Process Technology, Vol. 41 (5), 2020, 252-255; China Mechanical Engineering, Vol. 32 (3), 2021, 261-268). In the Chinese invention patent "A method for preparing a diamond microchannel heat sink for ultra-high heat flux density heat dissipation" (CN201810487436.6), a diamond microchannel heat sink is obtained by microgrooving the prepared self-supporting diamond thick film using laser processing technology and laser microbeam. However, due to the laser etching process and spot limit, the obtained diamond microgrooves are difficult to form a small size of depth and width, and are prone to high temperature damage and surface carbonization of the diamond heat sink, affecting the flow of coolant and heat transfer effect. In the Chinese invention patent "Diamond microchannel heat sink, preparation method and application, and semiconductor laser" (CN202010140690.6), a diamond microchannel heat sink was obtained by directly growing a diamond film and removing the substrate by wet etching. Although the contact area with the coolant was increased and ablation and carbonization during laser processing were avoided, the surface roughness of the obtained diamond microchannel was high, which increased the fluid resistance and affected the heat transfer effect of the heat sink. Therefore, based on the diamond heat sink material, research on more efficient heat dissipation processing technology and technology is of great significance to the realization of diamond microchannel heat dissipation devices. Summary of the invention

[0004] The present invention aims to provide a method for preparing a diamond microchannel heat sink with high thermal conductivity and low fluid resistance, by growing a diamond thick film on a single crystal silicon substrate and a dielectric layer film surface designed with a reverse microchannel gate hole structure, removing the silicon substrate and the dielectric layer film, and then growing a super-hydrophobic amorphous carbon-based film on the diamond core surface, thereby obtaining a diamond microchannel heat sink material with high thermal conductivity and low fluid resistance.

[0005] The present invention utilizes the high thermal conductivity of diamond materials, designs the microchannel frame structure of the dielectric layer film between diamond and silicon substrate, and deposits a super-hydrophobic active layer on the surface of the diamond microchannel, thereby realizing the preparation of a diamond microchannel heat sink with high thermal conductivity and low fluid resistance. Although the present invention also forms a diamond microchannel through a mask plate, it is significantly different from other methods. On the one hand, the special structural design of the dielectric layer film between the silicon substrate and the diamond can not only further reduce the physical property difference between the diamond and the substrate material, improve the diamond nucleation rate and growth rate, but also better control the depth-to-width ratio and shape of the diamond microchannel to achieve efficient heat conduction; on the other hand, a super-hydrophobic amorphous carbon-based film with good chemical stability is introduced on the surface of the diamond microchannel, which can not only improve the surface quality of the diamond and reduce the surface roughness, but also can utilize the super-hydrophobic characteristics to reduce the fluid resistance of the coolant and improve the heat transfer capacity of the diamond microchannel heat sink, which is of significant significance for improving the high heat dissipation application performance of power devices.

[0006] The invention provides a method for preparing a diamond microchannel heat sink with high thermal conductivity and low fluid resistance. The method comprises the following steps: depositing a dielectric layer film on the surface of a cleaned and polished single crystal silicon wafer substrate, etching a groove structure with a microchannel frame on the surface of the dielectric layer film using a mask plate with microchannel gate holes; epitaxially growing a diamond polycrystalline film on the surface of the dielectric layer film with the groove structure for multiple times to fill the grooves and cover the dielectric layer film, and thinning and polishing the growth surface of the diamond polycrystalline film to make it flat; removing the single crystal silicon wafer substrate and the dielectric layer film by pickling or etching, and treating the nucleation layer of the diamond polycrystalline film by plasma active etching to obtain a diamond wafer with a microchannel structure; and finally depositing a super hydrophobic amorphous carbon-based film on the surface of the diamond microchannel to obtain a diamond microchannel heat sink material with high thermal conductivity and low fluid resistance.

[0007] The method for preparing the high thermal conductivity and low fluid resistance diamond microchannel heat sink comprises the following steps:

[0008] (1) Fix the cleaned and polished single crystal silicon wafer substrate on the workpiece holder of the multi-excitation source plasma coating device. The distance between the silicon wafer and the excitation source is 8-20 cm, and the rotation speed of the workpiece holder is 1-10 r / min.

[0009] (2) Evacuate the multi-excitation source plasma coating chamber to a background vacuum of 1×10 −4 ~5×10 −4 Pa, adjust the argon gas intake into the vacuum chamber through the argon flowmeter, turn on the workpiece holder motor power supply, and use the ion source to sputter clean the single crystal silicon wafer;

[0010] (3) depositing a dielectric layer film on the surface of the single crystal silicon wafer substrate; the intermediate dielectric layer film is silicon nitride, silicon carbide or aluminum nitride, and the dielectric layer film preparation method includes electron beam evaporation, plasma enhanced chemical vapor deposition, laser melting evaporation or magnetron sputtering technology;

[0011] (4) Using a mask plate with microchannel gate holes of uniform aperture to closely contact the surface of the dielectric layer film, a groove structure with a microchannel frame is formed on the surface of the dielectric layer film by wet etching or ion beam etching;

[0012] (5) A layer of diamond polycrystalline film is slowly grown on the surface of the dielectric layer film with a microchannel frame structure by bias-enhanced nucleation using a microwave chemical vapor deposition method, the flow rates of methane and hydrogen are adjusted, and then the bias power supply is turned off to rapidly grow the diamond polycrystalline film to fill the groove structure and cover the dielectric layer film;

[0013] (6) thinning the grown diamond polycrystalline film by laser or ion thinning and precision polishing to a flat surface;

[0014] (7) removing the single crystal silicon wafer substrate and dielectric layer film by pickling or etching, and treating the nucleation layer of the diamond polycrystalline film by plasma active etching to obtain a self-supporting diamond wafer with a microchannel structure;

[0015] (8) A layer of super-hydrophobic amorphous carbon-based film is deposited on the surface of the self-supporting diamond microchannel using a multi-excitation source plasma coating device to obtain a self-supporting diamond microchannel heat sink with high thermal conductivity and low fluid resistance.

[0016] In the above preparation method, in step (1), the single crystal silicon wafer is ultrasonically cleaned with deionized water, acetone, anhydrous ethanol and deionized water in sequence for 5 to 20 minutes, and then blown dry with cold air for later use.

[0017] In the above preparation method, in step (2), during the ion source sputtering process, the vacuum chamber pressure is 5×10 −2 ~5×10 −1 Pa, the argon ion energy is 0.5~1.5 keV, and the cleaning time is 5~10 min.

[0018] In the above preparation method, in step (3), the thickness of the dielectric layer film is 50-300 nm.

[0019] In the above preparation method, in step (4), the thickness of the mask plate is 0.01-0.06 mm, the surface aperture size or groove width is 0.1-2 mm, the hole pitch or groove spacing is 0.05-0.2 mm, and the etching depth is 0.2-1 mm.

[0020] In the above preparation method, in step (5), the positive bias voltage used for bias-enhanced nucleation is 300~800 V, the flow ratio of methane to hydrogen is 1:500~1:50, the growth temperature is 700~1000 °C; the microwave power is 3~15 KW, and the deposition time is 200~600 h.

[0021] In the above preparation method, in step (6), the surface roughness of the diamond polycrystalline film after polishing is 5-50 nm.

[0022] In the above preparation method, in step (7), the surface roughness of the diamond polycrystalline film nucleation layer after etching is 1-10 nm.

[0023] In the above preparation method, in step (8), the thickness of the amorphous carbon-based film is 30-150 nm, and the static contact angle is 90-140°.

[0024] The beneficial effects of the present invention are as follows:

[0025] (1) The present invention uses high thermal conductivity diamond material as the microchannel heat dissipation medium, which can greatly improve the heat dissipation of the chip, reduce the local heat flux density, and is beneficial to improving the heat dissipation performance of the power device.

[0026] (2) The present invention reduces the physical property difference between diamond and substrate materials and improves the diamond nucleation rate and growth rate by designing the structure and composition of the dielectric layer film between the silicon substrate and the diamond, and can better control the aspect ratio and shape of the diamond microchannel, thereby achieving efficient heat conduction of the diamond microchannel.

[0027] (3) The present invention introduces a super-hydrophobic amorphous carbon-based film with good corrosion resistance, which can reduce the fluid resistance of the coolant while reducing the roughness of the diamond surface, thereby improving the heat transfer capacity of the diamond microchannel heat sink, which is of great significance for improving the high heat dissipation application performance of power devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of depositing a dielectric layer thin film on the surface of a single crystal silicon wafer substrate;

[0029] Figure 2 It is a schematic diagram of laminating a mask plate with a gate hole structure on the surface of a dielectric layer film on a single crystal silicon wafer substrate;

[0030] Figure 3 It is a schematic diagram of the dielectric layer film of the gate hole structure on the surface of the single crystal silicon wafer substrate after etching;

[0031] Figure 4 Schematic diagram of depositing diamond polycrystalline film on the surface of dielectric layer film of gate hole structure;

[0032] Figure 5Schematic diagram of the diamond polycrystalline film on the surface of the dielectric layer film of the gate hole structure after thinning and polishing;

[0033] Figure 6 Schematic diagram of a microchannel structure diamond wafer for removing a single crystal silicon substrate and a dielectric layer film;

[0034] Figure 7 Schematic diagram of depositing super-hydrophobic amorphous carbon-based film on the surface of self-supporting diamond microchannel.

[0035] In the figure: 1. Single crystal silicon wafer; 2. Dielectric layer film; 3. Mask plate; 4. Dielectric layer film with gate hole structure; 5. Diamond microchannel polycrystalline film; 6. Diamond microchannel polycrystalline film after polishing; 7. Amorphous carbon-based film. DETAILED DESCRIPTION

[0036] The present invention provides a method for preparing a high thermal conductivity and low fluid resistance diamond microchannel heat sink, which specifically comprises the following steps:

[0037] (1) The cleaned and polished single crystal silicon wafer 1 substrate is fixed on the workpiece rack of the multi-excitation source plasma coating device, the distance between the silicon wafer and the excitation source is 8-20 cm, and the workpiece rack rotation speed is 1-10 r / min. In the step (1), the single crystal silicon wafer 1 is ultrasonically cleaned with deionized water, acetone, anhydrous ethanol, and deionized water in sequence for 5-20 minutes, and then dried with cold air for standby use.

[0038] (2) Evacuate the multi-excitation source plasma coating chamber to a background vacuum of 1×10 −4 ~5×10 −4 Pa, the argon gas flow meter is used to adjust the argon gas intake into the vacuum chamber, the workpiece holder motor power is turned on, and the ion source is used to sputter and clean the single crystal silicon wafer 1. In step (2), during the ion source sputtering process, the vacuum chamber pressure is 5×10 −2 ~5×10 −1 Pa, the argon ion energy is 0.5~1.5 keV, and the cleaning time is 5~10 min.

[0039] (3) Depositing a dielectric layer film 2 on the surface of the single crystal silicon wafer substrate; the intermediate dielectric layer film is silicon nitride, silicon carbide or aluminum nitride, and the dielectric layer film preparation method includes electron beam evaporation, plasma enhanced chemical vapor deposition, laser melting evaporation or magnetron sputtering technology. In step (3), the dielectric layer film thickness is 50-300 nm.

[0040] (4) A mask plate 3 with microchannel gate holes of uniform aperture is placed close to the surface of the dielectric layer film 2, and a groove structure with a microchannel frame is formed on the surface of the gate hole structure dielectric layer film 4 by wet etching or ion beam etching. In the step (4), the mask plate thickness is 0.01-0.06 mm, the surface aperture size or the groove width is 0.1-2 mm, the hole pitch or the groove spacing is 0.05-0.2 mm, and the etching depth is 0.2-1 mm.

[0041] (5) A layer of diamond polycrystalline film is slowly grown on the surface of the dielectric layer film with the microchannel frame structure by bias-enhanced nucleation using a chemical vapor deposition method, and then the bias power supply is turned off to rapidly grow a diamond microchannel polycrystalline film 5 to fill the groove structure and cover the dielectric layer film. In the step (5), the positive bias voltage used for bias-enhanced nucleation is 300-800V, the flow ratio of methane to hydrogen is 1:500-1:50, the growth temperature is 700-1000°C; the microwave power is 3-15 KW, and the deposition time is 200-600 h.

[0042] (6) The grown diamond microchannel polycrystalline film is subjected to laser or ion thinning and precision polishing to a flat surface, i.e., the polished diamond microchannel polycrystalline film 6. In step (6), the surface roughness of the polished diamond microchannel polycrystalline film is 5-50 nm.

[0043] (7) The single crystal silicon wafer substrate and dielectric layer film are removed by pickling or etching, and the nucleation layer of the diamond polycrystalline film is treated by plasma active etching to obtain a self-supporting diamond wafer with a microchannel structure. In the step (7), the surface roughness of the diamond polycrystalline film nucleation layer after etching is 1-10 nm.

[0044] (8) A layer of super-hydrophobic amorphous carbon-based film 7 is deposited on the surface of the self-supporting diamond microchannel using a multi-excitation source plasma coating device to obtain a self-supporting diamond microchannel heat sink with high thermal conductivity and low fluid resistance. In the step (8), the thickness of the amorphous carbon-based film is 30-150 nm, and the static contact angle is 90-140°.

[0045] The present invention is further illustrated by the following examples, but is not limited to the following examples.

[0046] Embodiment 1:

[0047] This embodiment provides a method for preparing a diamond microchannel heat sink with high thermal conductivity and low fluid resistance, and the operation steps are as follows:

[0048] (1) The polished single crystal silicon wafer was ultrasonically cleaned with deionized water, acetone, anhydrous ethanol, and deionized water for 10 min in sequence. After being dried with cold air, it was fixed on the workpiece holder of the multi-excitation source plasma coating device. The distance between the silicon wafer and the excitation source was 10 cm, and the rotation speed of the workpiece holder was adjusted to 2 r / min.

[0049] (2) Evacuate the multi-excitation source plasma coating chamber to a background vacuum of 2×10 −4 Pa, and the argon gas flow meter was used to adjust the argon gas flow into the vacuum chamber so that the vacuum chamber pressure was maintained at ~6×10 −2 Pa, turn on the workpiece holder motor power supply, use the ion source to sputter clean the single crystal silicon wafer, the argon ion energy is 1.2 keV, and the cleaning time is 8 min.

[0050] (3) Using electron beam evaporation technology, a 100 nm thick silicon nitride dielectric film is deposited on the surface of a single crystal silicon wafer substrate. Figure 1 shown.

[0051] (4) Use a mask with uniform aperture microchannel grid holes to closely contact the surface of the dielectric layer film. The mask thickness is 0.02 mm, the surface aperture size or groove width is 0.3 mm, and the hole pitch or groove spacing is 0.1 mm. Figure 2 As shown; a groove structure with a microchannel frame is formed on the surface of the dielectric layer film by wet etching or ion beam etching, and the etching depth is 0.5 mm, as shown Figure 3 shown.

[0052] (5) A layer of diamond polycrystalline film was slowly grown on the surface of the dielectric layer film with a microchannel frame structure by bias-enhanced nucleation using a microwave plasma chemical vapor deposition method. The positive bias voltage used for bias-enhanced nucleation was 400 V, the methane to hydrogen flow ratio was 1:300, the microwave power was 7 kW, and the growth temperature was 850 °C. Then, the bias power supply was turned off, and the methane to hydrogen flow ratio was adjusted to 1:200 to rapidly grow a diamond polycrystalline film to fill the groove structure and cover the dielectric layer film. The deposition time was 500 h. Figure 4 shown.

[0053] (6) The diamond polycrystalline film grown above is laser thinned and precision polished to a flat surface. After polishing, the surface roughness of the diamond polycrystalline film is about 15 nm. Figure 5 shown.

[0054] (7) The single crystal silicon wafer substrate and dielectric layer film were removed by acid pickling, and the nucleation layer of the diamond polycrystalline film was treated by plasma active etching to obtain a self-supporting diamond wafer with a nucleation surface roughness of ~4 nm and a microchannel structure, such as Figure 6 shown.

[0055] (8) A super-hydrophobic amorphous carbon-based film with a thickness of ~50 nm was deposited on the surface of the self-supporting diamond microchannel using a multi-excitation source plasma coating device, and the static contact angle was 110°, thereby obtaining a self-supporting diamond microchannel heat sink with high thermal conductivity and low fluid resistance, such as Figure 7 shown.

[0056] Embodiment 2:

[0057] This embodiment provides a method for preparing a diamond microchannel heat sink with high thermal conductivity and low fluid resistance, and the operation steps are as follows:

[0058] (1) The polished single crystal silicon wafer was ultrasonically cleaned with deionized water, acetone, anhydrous ethanol, and deionized water for 15 min in sequence. After being dried with cold air, it was fixed on the workpiece holder of the multi-excitation source plasma coating device. The distance between the silicon wafer and the excitation source was 8 cm, and the rotation speed of the workpiece holder was adjusted to 5 r / min.

[0059] (2) Evacuate the multi-excitation source plasma coating chamber to a background vacuum of 2×10 −4 Pa, and the argon gas flow meter was used to adjust the argon gas flow into the vacuum chamber so that the vacuum chamber pressure was maintained at ~8×10 −2 Pa, turn on the workpiece holder motor power supply, use the ion source to sputter clean the single crystal silicon wafer, the argon ion energy is 1.5 keV, and the cleaning time is 5 min.

[0060] (3) A 150 nm thick silicon nitride dielectric film is deposited on the surface of a single crystal silicon wafer substrate using magnetron sputtering technology. Figure 1 shown.

[0061] (4) Use a mask with uniform aperture microchannel grid holes to closely contact the surface of the dielectric layer film. The mask thickness is 0.02 mm, the surface aperture size or groove width is 0.3 mm, and the hole pitch or groove spacing is 0.15 mm. Figure 2 As shown; a groove structure with a microchannel frame is formed on the surface of the dielectric layer film by wet etching or ion beam etching, and the etching depth is 0.8 mm, as shown Figure 3 shown.

[0062] (5) A layer of diamond polycrystalline film was slowly grown on the surface of the dielectric layer film with a microchannel frame structure by bias-enhanced nucleation using a microwave plasma chemical vapor deposition method. The positive bias voltage used for bias-enhanced nucleation was 600 V, the methane to hydrogen flow ratio was 1:400, the microwave power was 6 kW, and the growth temperature was 800 °C. Then, the bias power supply was turned off, and the methane to hydrogen flow ratio was adjusted to 1:200 to rapidly grow a diamond polycrystalline film to fill the groove structure and cover the dielectric layer film. The deposition time was 600 h. Figure 4 shown.

[0063] (6) The diamond polycrystalline film grown above is laser thinned and precision polished to a flat surface. After polishing, the surface roughness of the diamond polycrystalline film is about 12 nm. Figure 5 shown.

[0064] (7) The single crystal silicon wafer substrate and dielectric layer film are removed by pickling, and the nucleation layer of the diamond polycrystalline film is treated by plasma active etching to obtain a self-supporting diamond wafer with a nucleation surface roughness of ~2 nm and a microchannel structure, such as Figure 6 shown.

[0065] (8) A super-hydrophobic amorphous carbon-based film with a thickness of ~80 nm was deposited on the surface of the self-supporting diamond microchannel using a multi-excitation source plasma coating device, and the static contact angle was 100°, thereby obtaining a self-supporting diamond microchannel heat sink with high thermal conductivity and low fluid resistance, such as Figure 7 shown.

[0066] Embodiment 3:

[0067] This embodiment provides a method for preparing a diamond microchannel heat sink with high thermal conductivity and low fluid resistance, and the operation steps are as follows:

[0068] (1) The polished single crystal silicon wafer was ultrasonically cleaned with deionized water, acetone, anhydrous ethanol, and deionized water for 10 min in sequence. After being dried with cold air, it was fixed on the workpiece holder of the multi-excitation source plasma coating device. The distance between the silicon wafer and the excitation source was 12 cm, and the rotation speed of the workpiece holder was adjusted to 3 r / min.

[0069] (2) Evacuate the multi-excitation source plasma coating chamber to a background vacuum of 2×10 −4 Pa, and the argon gas flow meter was used to adjust the argon gas flow into the vacuum chamber so that the vacuum chamber pressure was maintained at ~8×10 −2 Pa, turn on the workpiece holder motor power supply, use the ion source to sputter clean the single crystal silicon wafer, the argon ion energy is 1.2 keV, and the cleaning time is 15 min.

[0070] (3) Plasma enhanced chemical vapor deposition technology is used to deposit a 200 nm thick silicon carbide dielectric layer film on the surface of a single crystal silicon wafer substrate. Figure 1 shown.

[0071] (4) Use a mask with uniform aperture microchannel grid holes to closely contact the surface of the dielectric layer film. The mask thickness is 0.05 mm, the surface aperture size or groove width is 0.5 mm, and the hole pitch or groove spacing is 0.08 mm. Figure 2As shown; a groove structure with a microchannel frame is formed on the surface of the dielectric layer film by wet etching or ion beam etching, and the etching depth is 0.4 mm, as shown Figure 3 shown.

[0072] (5) A layer of diamond polycrystalline film was slowly grown on the surface of the dielectric layer film with a microchannel frame structure by bias-enhanced nucleation using a microwave plasma chemical vapor deposition method. The positive bias voltage used for bias-enhanced nucleation was 600 V, the methane to hydrogen flow ratio was 1:200, the microwave power was 6 kW, and the growth temperature was 800 °C. Then, the bias power supply was turned off, and the methane to hydrogen flow ratio was adjusted to 1:200 to rapidly grow a diamond polycrystalline film to fill the groove structure and cover the dielectric layer film. The deposition time was 600 h. Figure 4 shown.

[0073] (6) The diamond polycrystalline film grown as above is laser thinned and precision polished to a flat surface. After polishing, the surface roughness of the diamond polycrystalline film is about 20 nm. Figure 5 shown.

[0074] (7) The single crystal silicon wafer substrate and dielectric layer film are removed by pickling and ion etching, and the nucleation layer of the diamond polycrystalline film is treated by plasma active etching to obtain a self-supporting diamond wafer with a nucleation surface roughness of ~ 5 nm and a microchannel structure, such as Figure 6 shown.

[0075] (8) A super-hydrophobic amorphous carbon-based film with a thickness of ~120 nm was deposited on the surface of the self-supporting diamond microchannel using a multi-excitation source plasma coating device, and the static contact angle was 120°, thereby obtaining a self-supporting diamond microchannel heat sink with high thermal conductivity and low fluid resistance, such as Figure 7 shown.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that there are many practical solutions that can be adopted in the preparation method, and any equivalent modifications or substitutions made in accordance with the claims of the present invention and the essence of the corresponding technical solutions belong to the scope of the present invention.

Claims

1. A method for preparing a high thermal conductivity and low fluid resistance diamond microchannel heat sink, characterized in that The method comprises the following steps: firstly, depositing a dielectric layer film on the surface of a cleaned and polished single crystal silicon wafer substrate, and using a mask plate with microchannel gate holes to form a groove structure with a microchannel frame on the surface of the dielectric layer film by etching; A diamond polycrystalline film is epitaxially grown multiple times on the surface of the dielectric layer film with the groove structure to fill the grooves and cover the dielectric layer film, and the growth surface of the diamond polycrystalline film is thinned and polished to be flat; The single crystal silicon wafer substrate and dielectric layer film are removed by pickling or etching, and the nucleation layer of the diamond polycrystalline film is treated by plasma active etching to obtain a diamond wafer with a microchannel structure; Finally, a super-hydrophobic amorphous carbon-based film is deposited on the surface of the diamond microchannel, thereby obtaining a diamond microchannel heat sink with high thermal conductivity and low fluid resistance; The method for preparing the high thermal conductivity and low fluid resistance diamond microchannel heat sink comprises the following steps: (1) Fix the cleaned and polished single crystal silicon wafer substrate on the workpiece holder of the multi-excitation source plasma coating device. The distance between the silicon wafer and the excitation source is 8-20 cm, and the rotation speed of the workpiece holder is 1-10 r / min. (2) Evacuate the multi-excitation source plasma coating chamber to a background vacuum of 1×10 −4 ~5×10 −4 Pa, adjust the argon gas intake into the vacuum chamber through the argon flowmeter, turn on the workpiece holder motor power supply, and use the ion source to sputter clean the single crystal silicon wafer; (3) Depositing a dielectric layer film on the surface of the single crystal silicon wafer substrate; the dielectric layer film is silicon nitride, silicon carbide or aluminum nitride, and the dielectric layer film preparation method includes electron beam evaporation, plasma enhanced chemical vapor deposition, laser melting evaporation or magnetron sputtering technology; the dielectric layer film thickness is 50~300 nm; (4) Using a mask plate with microchannel gate holes of uniform aperture to closely contact the surface of the dielectric layer film, a groove structure with a microchannel frame is formed on the surface of the dielectric layer film by wet etching or ion beam etching; (5) A layer of diamond polycrystalline film is slowly grown on the surface of the dielectric layer film with a microchannel frame structure by bias-enhanced nucleation using a microwave chemical vapor deposition method, the amount of methane and hydrogen is adjusted, and then the bias power supply is turned off to rapidly grow the diamond polycrystalline film to fill the groove structure and cover the dielectric layer film; (6) thinning the grown diamond polycrystalline film by laser or ion thinning and precision polishing to a flat surface; (7) removing the single crystal silicon wafer substrate and dielectric layer film by pickling or etching, and treating the nucleation layer of the diamond polycrystalline film by plasma active etching to obtain a self-supporting diamond wafer with a microchannel structure; (8) A multi-excitation source plasma coating device was used to deposit a layer of super-hydrophobic amorphous carbon-based film on the surface of the self-supporting diamond microchannel. The thickness of the amorphous carbon-based film was 30~150 nm, and a diamond microchannel heat sink with high thermal conductivity and low fluid resistance was obtained.

2. The method for preparing the high thermal conductivity and low fluid resistance diamond microchannel heat sink according to claim 1, characterized in that: In the step (1), the single crystal silicon wafer is ultrasonically cleaned with deionized water, acetone, anhydrous ethanol, and deionized water in sequence for 5 to 20 minutes, and then blown dry with cold air for later use.

3. The method for preparing the high thermal conductivity and low fluid resistance diamond microchannel heat sink according to claim 1, characterized in that: In the step (2), during the ion source sputtering process, the vacuum chamber pressure is 5×10 −2 ~5×10 −1 Pa, the argon ion energy is 0.5~1.5 keV, and the cleaning time is 5~10 min.

4. The method for preparing the high thermal conductivity and low fluid resistance diamond microchannel heat sink according to claim 1, characterized in that: In the step (4), the thickness of the mask plate is 0.01-0.06 mm, the surface aperture size or groove width is 0.1-2 mm, the hole pitch or groove spacing is 0.05-0.2 mm, and the etching depth is 0.2-1 mm; the ratio of the etching depth to the hole pitch or groove spacing is not less than 5:

1.

5. The method for preparing the high thermal conductivity and low fluid resistance diamond microchannel heat sink according to claim 1, characterized in that: In the step (5), the positive bias voltage used for bias-enhanced nucleation is 300-800 V, the flow ratio of methane to hydrogen is 1:500-1:50, the growth temperature is 700-1000 °C, the microwave power is 3-15 KW, and the deposition time is 200-600 h.

6. The method for preparing the high thermal conductivity and low fluid resistance diamond microchannel heat sink according to claim 1, characterized in that: In the step (6), the surface roughness of the diamond polycrystalline film after polishing is 5-50 nm.

7. The method for preparing the high thermal conductivity and low fluid resistance diamond microchannel heat sink according to claim 1, characterized in that: In the step (7), the surface roughness of the nucleation layer of the diamond polycrystalline film after etching is 1-10 nm.

8. The method for preparing the high thermal conductivity and low fluid resistance diamond microchannel heat sink according to claim 1, characterized in that: In the step (8), the static contact angle of the amorphous carbon-based film is 90-140°.

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