CN207775345U - Diamond/graphene composite heat conduction film and cooling system - Google Patents

Abstract

The utility model provides a diamond/graphene composite thermal conduction film, which comprises a micron crystal diamond film and a graphene layer arranged on the surface of the micron crystal diamond film. In the diamond/graphene composite thermal conduction film, the bonding force between diamond and graphene is strong, and the interfacial thermal resistance between diamond and graphene is low, so the formed diamond/graphene composite thermal conduction film has efficient thermal conductivity. The utility model also provides a cooling system. The heat dissipation system includes a heating element, a heat sink and a heat conduction film, and the heat conduction film includes the above-mentioned diamond/graphene composite heat conduction film, and the heat conduction film is pasted between the heat generation element and the heat sink, so that The heating element transmits heat to the heat sink through the heat conduction film to dissipate heat. The heat conduction film can exist independently of heating elements and heat dissipation devices, and can be picked up and placed, so it is easy to industrialized production and use, and has excellent heat dissipation performance.

Description

Diamond/Graphene Composite Thermal Conductive Film and Heat Dissipation System

technical field

The utility model relates to the field of heat conduction films, in particular to a diamond/graphene composite heat conduction film and a heat dissipation system.

Background technique

At present, diamond heat sinks and graphene-based composite materials have been used in the thermal management of high-end high-power devices. advantage has become a research hotspot. For example, the invention patent CN201510406256.7 discloses "a method for preparing an ultra-high directional thermal conductivity carbon-based composite material". The surface of natural or synthetic diamond is precisely polished and cleaned to achieve atomic level flatness; Graphene based on methyl acrylate (PMMA) substrate is directly spread on the diamond surface to obtain a highly directional thermal conductivity composite material. However, in this patent, the graphene based on the PMMA substrate is transferred to the diamond. The obtained graphene and diamond have low bonding force, poor interface bonding, high interface thermal resistance, and complicated preparation process.

Therefore, it is necessary to provide a novel diamond/graphene composite heat-conducting film.

Utility model content

In order to solve the above problems, the utility model provides a diamond/graphene composite heat-conducting film, in which a graphene layer is arranged on the surface of the microcrystalline diamond film, and the bonding force between the microcrystalline diamond film and the graphene layer is strong and the resulting The heat dissipation performance of the diamond/graphene composite heat conduction film is better.

The utility model provides a diamond/graphene composite heat conduction film, which comprises a micron crystal diamond film and a graphene layer arranged on the surface of the micron crystal diamond film.

Wherein, the graphene layer includes single-layer graphene or multi-layer graphene.

Wherein, the thickness of the graphene layer is 1-60 atomic thickness.

Wherein, the graphene layer includes a single layer of graphene paved on the surface of the microcrystalline diamond film.

Wherein, the graphene layer further includes vertical graphene vertically grown on the single-layer graphene.

Wherein, the vertical graphene is arranged in an array.

Wherein, the thickness of the microcrystalline diamond film is 200 μm-2 mm.

Wherein, the grain size of the microcrystalline diamond is 1 μm-10 μm.

Wherein, the diamond/graphene composite heat conduction film further includes a transition metal layer, and the transition metal layer is located on the side of the microcrystalline diamond film away from the graphene layer.

The diamond/graphene composite heat conduction film provided by the utility model has a strong bonding force between diamond and graphene, forming an excellent heat conduction structure. High thermal conductivity in the vertical direction, low interfacial thermal resistance between diamond and graphene, and efficient thermal conductivity of the composite film structure as a whole.

The utility model also provides a heat dissipation system, including a heating element, a radiator and a heat conducting film, the heat conducting film includes the above-mentioned diamond/graphene composite heat conducting film, and the heat conducting film is pasted on the heating element and between the heat sinks, so that the heating element transfers heat to the heat sink through the heat conduction film to dissipate heat.

The heat dissipation system provided by the utility model includes a heat conduction film, which can exist independently of heating elements and heat dissipation devices, and can be picked up and pasted, so it is easy to industrialized production and use, and has excellent heat dissipation performance.

Description of drawings

Fig. 1 is the structural schematic diagram of the diamond/graphene composite thermal conduction film that one embodiment of the present invention provides;

Fig. 2 is a schematic structural diagram of a diamond/graphene composite heat-conducting film provided by another embodiment of the present invention.

Detailed ways

The following description is a preferred embodiment of the present utility model. It should be pointed out that for those of ordinary skill in the art, some improvements and modifications can also be made without departing from the principle of the present utility model. These improvements and modifications It is also regarded as the protection scope of the present utility model.

As shown in FIG. 1 , the first aspect of the embodiment of the present invention provides a diamond/graphene composite heat-conducting film, including a microcrystalline diamond film 1 and a graphene layer 2 disposed on the surface of the microcrystalline diamond film.

In the implementation manner of the present utility model, the crystal grains in the microcrystalline diamond are of micron order. Optionally, the grain size of the microcrystalline diamond is 1 μm-10 μm. Optionally, the thickness of the microcrystalline diamond film is 200 μm-2 mm. Optionally, the microcrystalline diamond film may be a disc with a diameter of 20-50 cm. Further optionally, the microcrystalline diamond film is a disc with a diameter of 25.4 cm. In the utility model, a graphene layer is arranged on the surface of the microcrystalline diamond film. Since the diamond film has a high-quality microcrystalline structure, the microcrystalline diamond film has a higher thermal conductivity than the nanocrystalline diamond film. In addition, the size of the microcrystalline diamond film in the embodiment of the present invention is relatively large, which can meet the demand for large-area diamond/graphene composite heat-conducting films in high-power electronic devices.

In the embodiment of the present utility model, the graphene layer includes single-layer graphene or multi-layer graphene. Optionally, the graphene layer has a thickness of 1-60 atoms. As shown in FIG. 2 , further optionally, the graphene layer includes a single layer of graphene 21 paved on the surface of the microcrystalline diamond film 1 . The single-layer graphene is a two-dimensional network film with a thickness of one carbon atom. The single-layer graphene is tiled on the surface of the microcrystalline diamond film, that is, the extension direction of the single-layer graphene is parallel to the surface of the microcrystalline diamond film. Further optionally, the graphene layer further includes vertical graphene 22 vertically grown on the single-layer graphene 21 . That is, the vertical graphene grows vertically on the surface of the microcrystalline diamond film. Since the vertical graphene has a very high specific surface area, the effective heat dissipation area of the composite film surface can be improved. Further optionally, the vertical graphene is arranged in an array. Further optionally, the vertical graphene has a thickness of 1-60 atoms. Further optionally, the graphene layer includes multilayer graphene paved on the surface of the microcrystalline diamond film and vertical graphene vertically grown on the multilayer graphene.

In the embodiment of the present invention, the graphene layer is obtained by nucleation and growth on the basis of the microcrystalline diamond film.

In the embodiment of the present utility model, the diamond/graphene composite heat conduction film further includes a transition metal layer, and the transition metal layer is located on the side of the microcrystalline diamond film away from the graphene layer. Optionally, the diamond/graphene composite heat conduction film sequentially includes a transition metal layer, a microcrystalline diamond film and a graphene layer, and the transition metal layer is located at the bottom of the microcrystalline diamond film.

The diamond/graphene composite heat conduction film provided in the first aspect of the embodiment of the utility model has a strong bonding force between microcrystalline diamond and graphene, forming an excellent heat conduction structure, and graphene is conducive to improving high heat in the direction of the two-dimensional structure Conductivity, diamond is conducive to improving the longitudinal high thermal conductivity in the vertical plane direction, and has a low interface thermal resistance between diamond and graphene, and the composite film structure as a whole has efficient thermal conductivity.

The second aspect of the embodiment of the utility model provides a method for preparing a diamond/graphene composite heat-conducting film, including:

S01, providing a substrate, depositing a microcrystalline diamond film on the surface of the substrate;

S02, removing the substrate by etching to obtain a self-supporting microcrystalline diamond film; wherein, the self-supporting microcrystalline diamond film includes a surface to be nucleated, and the surface to be nucleated is the microcrystalline diamond film before etching a contact surface with said substrate;

S03, depositing a transition metal layer on the surface to be nucleated, placing the self-supporting microcrystalline diamond film deposited with the transition metal layer in the cavity of a hot wire vapor deposition chamber for rapid annealing, to obtain the diamond/graphite The annealing temperature is 800-1100° C., and the annealing time is 1-5 minutes.

In S01, the substrate includes single crystal silicon or a metal substrate such as molybdenum, copper, iron and the like. Optionally, the substrate is a single crystal silicon substrate. Optionally, before preparing the microcrystalline diamond film, the single crystal silicon substrate is pretreated, and the pretreatment operation includes:

Put the monocrystalline silicon substrate into the mixed solution of NH ₄ OH/H ₂ O ₂ /deionized water (volume ratio 1:1:5), heat to 70°C-80°C for 1-2 hours, and rinse the silicon wafer clean, and then put the silicon chip into acetone solution for 10-30 minutes for ultrasonic cleaning, deionized water for 10-30 minutes and alcohol solution for 10-30 minutes.

In the embodiment of the present utility model, before preparing the microcrystalline diamond film, the substrate is subjected to an enhanced nucleation treatment process to increase the nucleation density of diamond, and the nucleation treatment process includes placing the substrate on diamond powder Ultrasonic treatment in suspension or placing the substrate in a vapor deposition chamber for bias-enhanced nucleation.

Specifically, the operation of placing the substrate in a suspension of diamond powder for ultrasonic treatment includes:

The substrate is placed in the suspension of nano-diamond powder for ultrasonic treatment for 1-3 hours. Optionally, the average particle size of the nano-diamond powder in the nano-diamond powder suspension is 5 nm. Optionally, the Zeta potential of the nano-diamond powder suspension is about ±50mV.

Specifically, the operation of placing the substrate in a vapor deposition chamber for bias-enhanced nucleation treatment includes:

Taking HFCVD as an example, dual-bias hot wire chemical vapor deposition is used. During the nucleation process, a positive bias is applied to the grid above the hot wire, and a negative bias is applied to the silicon substrate; for microwave plasma CVD, a negative bias is applied to the substrate. The proportion of methane in the nucleation process is slightly higher, and the nucleation process is completed after about half an hour. Turn off the bias power supply, adjust the methane concentration and other process parameters to conditions suitable for the growth of high thermal conductivity microcrystalline diamond films. Specifically: HFCVD gate bias is +30V, base bias is -150V; plasma CVD base bias is -150V.

After the above enhanced nucleation treatment process, the nucleation density of the microcrystalline diamond film is greater than 10 ¹⁰ /cm ² .

In S01, after an enhanced nucleation treatment process, a microcrystalline diamond film is prepared on the surface of the substrate. Optionally, the preparation process is chemical vapor deposition, and the chemical vapor deposition method includes microwave plasma chemical vapor deposition (MPCVD) or hot wire chemical vapor deposition (HFCVD) preparation.

Specifically, the specific parameters of the HFCVD are as follows:

The gaseous carbon source and hydrogen are fed into the hot wire chemical vapor deposition, the air pressure is 3000-5000Pa, the power of the hot wire is 5000-8000W, the substrate temperature is 500°C-1000°C, and the deposition time is 100-300 hours. More specifically, the hot wire array is composed of nine tantalum wires with a diameter of 0.5 mm. The distance between the hot wire and the sample surface is 8 mm. The wire power was 7000W, the substrate temperature was 900°C, and the deposition time was 200 hours.

Specifically, the specific parameters of microwave plasma chemical vapor deposition (MPCVD) are as follows:

The gaseous carbon source and hydrogen gas are fed in for microwave plasma chemical vapor deposition, the pressure is 20-40Torr, the microwave power is 1000-1500W, the substrate temperature is 700-900°C, and the deposition time is 100-300 hours. More specifically, the flow rate of methane/hydrogen is 2sccm/298sccm, the total gas flow rate is 300sccm, the gas pressure is 30Torr, the microwave power is 1200W, the substrate temperature is 850°C, and the deposition time is 200 hours.

In the above technical scheme, besides microwave plasma chemical vapor deposition and hot filament chemical vapor deposition, the method of growing diamond film can also be direct current, radio frequency, hot cathode or jet plasma chemical vapor deposition, etc., which can grow diamond any method.

In S02, the prepared microcrystalline diamond film is separated from the substrate to obtain a self-supporting microcrystalline diamond film. Alternatively, a self-supporting microcrystalline diamond film can be obtained by etching the substrate with a mixed solution of hydrofluoric acid/sulfuric acid/glacial acetic acid. Alternatively, a self-supporting microcrystalline diamond film can be obtained after etching the substrate by a KOH solution. Specifically, the etching operation is: placing the substrate deposited with a microcrystalline diamond film in a mixed solution of hydrofluoric acid/sulfuric acid/glacial acetic acid in a volume ratio of 1:1:2 for etching; or depositing The substrate with the microcrystalline diamond film is placed in a 30% (w/v) KOH solution, heated to 85°C-100°C for corrosion, the corrosion time is 5-24 hours, and then the obtained self-supporting diamond film is cleaned ,drying. After corrosion, the surface to be nucleated (that is, the contact surface between the diamond film and the substrate before corrosion) is very smooth and can be used as a growth surface of high-quality graphene. Optionally, the surface roughness (rms, roughness) of the surface to be nucleated is <1 nm.

The utility model uses the nucleation surface of the diamond film to grow graphene, provides a diamond surface with atomic level flatness, avoids the complex process of chemical mechanical polishing of the rough micron crystal diamond film, and at the same time, the diamond film has high-quality micron Compared with the nanocrystalline diamond film with higher flatness, the microcrystalline diamond film has a higher thermal conductivity.

In S03, a transition metal layer is deposited on the surface to be nucleated. Specifically, the self-supporting microcrystalline diamond film is placed in an electron beam deposition device, the device is turned on until the background vacuum reaches 1×10 ^-7 -1×10 ^-8 Torr, the electron beam is turned on, and the high voltage of the electron beam is adjusted and current, keep the transition metal deposition rate at 0.3-0.8nm/s, and the deposition time at 15-30s. Specifically, turn on the equipment until the background vacuum reaches 10 ^-8 Torr, turn on the electron beam, adjust the high voltage and current of the electron beam, and keep the transition metal deposition rate at 0.5nm/s and the deposition time at 20s.

Optionally, the thickness of the transition metal layer deposited before annealing is 1 nm-50 nm, and the material of the transition metal layer includes nickel, copper, iron or cobalt.

In S03, after the transition metal layer is prepared, the self-supporting microcrystalline diamond film deposited with the transition metal layer is placed in the cavity of a hot wire vapor deposition chamber for rapid annealing to obtain the diamond/graphene composite heat conducting film.

Alternatively, the sample is placed in the HFCVD equipment, and a high-quality graphene nucleation layer can be obtained through a similar rapid annealing process in which the hot wire is rapidly heated up and turned off, and the process conditions need to be optimized in this process. Optionally, the specific parameters of the annealing process are as follows: a protective gas and hydrogen gas are introduced into the cavity of the hot wire vapor deposition chamber so that the pressure in the cavity is 2800-3200Pa, and the gas phase of the hot wire is The distance between the hot wire in the deposition chamber cavity and the surface of the microcrystalline diamond film is 4-10mm, the power of the hot wire is 5000-7000W, and the temperature of the self-supporting microcrystalline diamond film deposited with a transition metal layer is 800 -1100℃, the holding time is 1-5min. Further optionally, the protective gas is nitrogen, the protective gas is nitrogen, the flow rate of nitrogen and hydrogen is 425 sccm/75 sccm, and the total gas flow rate is 500 sccm. Specifically, the hot wire array is composed of nine tantalum wires with a diameter of 0.5 mm, the distance between the hot wire and the surface of the self-supporting microcrystalline diamond film deposited with a transition metal layer is 5 mm, the air pressure is 3000 Pa, and the power of the hot wire is 7000 W. The temperature of the self-supporting microcrystalline diamond film deposited with the transition metal layer was 1100° C., and the holding time was 1 min.

Optionally, after the annealing is completed, the temperature is lowered to 200°C-400°C at a rate of 30-50°C/min. Optionally, after annealing, the temperature is lowered to 200°C-300°C at a rate of 40°C/min.

During the annealing process, the transition metal layer continues to sink until it reaches the bottom of the microcrystalline diamond film. It is understood that some transition metal particles may penetrate into the microcrystalline diamond film.

In the embodiment of the utility model, the utility model adopts hot wire chemical vapor deposition equipment to carry out the nucleation and growth of graphene. Compared with other rapid annealing methods, HFCVD can provide more suitable atmosphere conditions and plasma environment for graphene growth. , which is conducive to improving the quality of graphene. Inducing the nucleation and growth of graphene with a transition metal layer, without adding carbon sources such as methane, the transition metal in the transition metal layer catalyzes part of the carbon elements in the microcrystalline diamond film to form a graphene layer, The self-assembly transformation of the surface carbon atomic layer from diamond structure to graphene structure is realized by the diffusion of diamond and transition metal layers.

In the embodiment of the present invention, the graphene layer obtained after the annealing treatment includes single-layer or multi-layer graphene tiled on the surface of the microcrystalline diamond film.

In the embodiment of the present invention, the graphene layer obtained after the annealing treatment comprises a single-layer graphene tiled on the surface of the microcrystalline diamond film, and then prepares vertical growth on the single-layer graphene according to the following method Vertical graphene on the monolayer graphene:

After the annealing treatment, a carbon source gas is introduced into the cavity of the hot wire vapor deposition chamber for deposition to obtain vertical graphene. The specific growth parameters are: gaseous carbon source, hydrogen and argon are fed into the hot wire chemical vapor deposition, the deposition temperature is 600-800°C, the pressure is 3000-6000Pa, the power is 5000-7000W, and the deposition time is 2-3 hours. Optionally, the gaseous carbon source includes one of C ₂ H ₂ , CH ₄ , CF ₄ , CHF ₃ and C ₂ F ₆ . Optionally, the specific growth parameters are as follows: the ratio of CH ₄ , H ₂ , Ar is 40%:40%:20%, the air pressure is 4000Pa, the power of the filament is 6000W, the deposition temperature is 800°C, and the deposition time is 2h. More specifically, the argon/methane/hydrogen gas flow is 200 sccm/400 sccm/400 sccm, and the total gas flow is 1000 sccm.

In the embodiment of the present utility model, the graphene layer obtained after the annealing treatment includes a single-layer graphene tiled on the surface of the microcrystalline diamond film, and then continues to prepare several layers on the single-layer graphene according to the following method Graphene to get multilayer graphene:

After the annealing treatment, a carbon source gas is introduced into the cavity of the hot wire vapor deposition chamber for deposition to obtain multilayer graphene. The specific growth parameters are: gaseous carbon source, hydrogen and argon are fed into the hot wire chemical vapor deposition, the deposition temperature is 800-1100°C, the pressure is 3000-6000Pa, the power is 5000-7000W, and the deposition time is 1-1.5h. Optionally, the gaseous carbon source includes one of C ₂ H ₂ , CH ₄ , CF ₄ , CHF ₃ and C ₂ F ₆ . Specifically, the growth of graphene was continued in HFCVD, and the specific growth parameters were as follows: the air pressure was 3000Pa, and the power of the hot wire was 7000W. More specifically, the nitrogen/hydrogen/methane flow rate is 410 sccm/75 sccm/15 sccm, and the total gas flow rate is 500 sccm.

The utility model uses the diamond film nucleation surface as the substrate for graphene growth, which is conducive to the smooth and continuous high-quality graphene growth. Through the annealing process, a high-quality graphene nucleation layer can be obtained. The preparation method is simple and easy to operate , the prepared diamond/graphene composite heat conduction film has a high thermal conductivity.

The third aspect of the embodiment of the utility model provides a heat dissipation system, including a heating element, a heat sink, and a heat conduction film, and the heat conduction film includes the diamond/graphene composite heat conduction film as described in the first aspect above, and the heat conduction film Pasted between the heating element and the radiator, so that the heating element transfers heat to the radiator through the heat conduction film to dissipate heat.

In the heat dissipation system provided by the utility model, the diamond/graphene composite heat conduction film has higher thermal conductivity than the diamond heat dissipation film, especially the graphene greatly improves the heat conduction performance in the plane, and the high-density heat flow of the point heat source The rapid diffusion to the entire plane first reduces the heat flux density entering the diamond, and then the heat flow is exported in the horizontal and/or vertical direction through the diamond film, which greatly improves the heat dissipation performance.

The above-mentioned embodiments only express several implementations of the utility model, and the description thereof is relatively specific and detailed, but it should not be construed as limiting the patent scope of the utility model. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the scope of protection of the utility model patent should be based on the appended claims.

Claims (7)

1. A diamond/graphene composite heat-conducting film is characterized in that it comprises a microcrystalline diamond film and a graphene layer arranged on the surface of the microcrystalline diamond film, and the graphene layer includes a layer of microcrystalline diamond laid on the surface of the microcrystalline diamond film. Single-layer or multi-layer graphene on the surface of the film and vertical graphene vertically grown on the single-layer or multi-layer graphene. 2. The diamond/graphene composite heat-conducting film according to claim 1, wherein the thickness of the graphene layer is 1-60 atomic thickness. 3. The diamond/graphene composite heat-conducting film according to claim 1, wherein the vertical graphene is arranged in an array. 4. The diamond/graphene composite heat-conducting film according to claim 1, wherein the thickness of the microcrystalline diamond film is 200 μm-2mm. 5. The diamond/graphene composite heat-conducting film according to claim 1, wherein the grain size of the microcrystalline diamond is 1 μm-10 μm. 6. The diamond/graphene composite heat-conducting film as claimed in claim 1, characterized in that, the diamond/graphene composite heat-conducting film also includes a transition metal layer, and the transition metal layer is positioned at the farthest point from the microcrystalline diamond film. one side of the graphene layer. 7. A heat dissipation system, characterized in that it comprises a heating element, a radiator and a thermally conductive film, the thermally conductive film comprises the diamond/graphene composite thermally conductive film according to any one of claims 1-6, and the thermally conductive film is pasted placed between the heating element and the radiator, so that the heating element transfers heat to the radiator through the heat conduction film to dissipate heat.