CN101626674B - Radiating structure and preparation method thereof - Google Patents

Abstract

A heat dissipation structure, the heat dissipation structure is fixedly arranged on the surface of a heating element, wherein the heat dissipation structure includes a patterned carbon nanotube array and a fixed layer, and the heat dissipation structure is fixed on the heating element through the fixing layer, so The patterned carbon nanotube array includes a plurality of carbon nanotubes, the lengths of the plurality of carbon nanotubes exposing the fixed layer are not equal, forming a predetermined pattern. A method for preparing a heat dissipation structure, which includes the following steps: providing a heating element, the heating element has a surface; setting a molten state fixed layer on the surface of the heating element; preparing a carbon nanotube array formed on a substrate, the carbon The nanotube array has a first end and a second end opposite to the first end, and the second end is connected to the substrate; the first end of the carbon nanotube array is inserted into the fixed layer, and the fixed layer is cooled until it is solidified; removing the base of the carbon nanotube array; and patterning the carbon nanotube array to form a heat dissipation structure on the surface of the heating element.

Description

Heat dissipation structure and preparation method thereof

technical field

The invention relates to a heat dissipation structure and a preparation method thereof, in particular to a heat dissipation structure based on carbon nanotubes and a preparation method thereof.

Background technique

In recent years, with the rapid development of the integration process of semiconductor devices, the degree of integration of semiconductor devices is getting higher and higher, and the operating frequency of semiconductor integrated devices (such as CPU) is also getting higher and higher, and the heat generated per unit time increases. The accumulation will cause the temperature to rise, which will lead to the decrease of the operating performance of the semiconductor integrated device including the stability. Therefore, it is necessary to dissipate the heat generated in time. At present, heat dissipation has become a problem that must be solved in the semiconductor integration process.

With the reduction of the device volume, its heat dissipation requirement is increased, and the heat dissipation of the device has become an important issue. Referring to FIG. 1 , a heat dissipation structure 100 currently used for heat dissipation of devices generally includes a heat sink 102 and a thermal interface material layer 104 . The heat sink 102 includes a base body 106 and cooling fins 108 disposed on the base body 106 . The thermal interface material layer 104 is usually arranged on the surface opposite to the substrate 106 of the heat sink 102 and the heat dissipation fins 108, and is used to increase the heat dissipation area between the heat dissipation structure 100 and the semiconductor device, and improve the heat transfer between the semiconductor device and the heat dissipation structure 100 Effect. Traditional thermal interface materials are composite materials formed by dispersing particles with high thermal conductivity in a polymer matrix. Materials with high thermal conductivity include graphite, boron nitride, silicon oxide, aluminum oxide, silver or other metals. The general defect of this type of composite material is that the thermal conductivity of the overall material is small, with a typical value of 1W/mK, which can no longer meet the heat dissipation requirements of the increased integration of semiconductors. Moreover, due to the existence of the thermal interface material layer, the volume of this heat dissipation structure is limited, and it is difficult to meet the requirements of tiny semiconductor devices. In addition, the materials of traditional heat dissipation fins often use metal, metal alloy or composite materials formed by dispersing particles with high thermal conductivity in the polymer matrix. The heat dissipation fins made of these materials also have the disadvantage of low thermal conductivity. , it is difficult to meet the demand for heat dissipation as the degree of semiconductor integration increases.

In 1991, Japanese scientist Iijima discovered carbon nanotubes in arc discharge experiments (see "Helical microtubules of graphitic carbon", Nature, Sumio Iijima, vol354, p56(1991)). Because carbon nanotubes have a large aspect ratio, the length can be thousands of times the diameter; the strength is high, 100 times that of steel, but the weight is only one-sixth of steel; the characteristics of excellent toughness and elasticity, and carbon nanotubes It has extremely high thermal conductivity along its longitudinal direction, making it one of the most potential thermal interface materials. An article titled "Significant thermal conductivity of carbon nanotubes" published by the American Physical Society pointed out that the thermal conductivity of "Z"-shaped (10,10) carbon nanotubes can reach 6600W/mK at room temperature. The nature of carbon nanotubes makes them have broad development prospects in the application of heat dissipation structures in semiconductor integrated devices, and has become a research hotspot.

In the prior art, when carbon nanotubes are applied to heat dissipation structures, carbon nanotubes themselves or composite materials of carbon nanotubes are usually used as thermal interface materials. However, since the carbon nanotubes are generally arranged disorderly in the thermal interface material, the advantage of longitudinal heat conduction of the carbon nanotubes cannot be fully utilized, so the heat dissipation efficiency of this heat dissipation structure has not been significantly improved. At the same time, since this heat dissipation structure also needs to include a thermal interface material and a heat sink at the same time, the volume of the heat dissipation structure is limited and cannot meet the requirements of tiny devices.

Therefore, it is indeed necessary to provide a heat dissipation structure and a preparation method thereof. The heat dissipation structure has high heat dissipation efficiency, small volume, and can be conveniently applied in various fields.

Contents of the invention

A heat dissipation structure, the heat dissipation structure is fixedly arranged on the surface of a heating element, wherein the heat dissipation structure includes a patterned carbon nanotube array and a fixed layer, the heat dissipation structure is fixed on the heating element through the fixing layer, the The melting point of the heating element is higher than the melting point of the fixing layer, and the patterned carbon nanotube array includes a plurality of carbon nanotubes, and the lengths of the plurality of carbon nanotubes exposed to the fixing layer are not equal to form a predetermined pattern.

A method for preparing a heat dissipation structure, comprising the following steps: providing a heating element, the heating element has a surface; setting a molten fixed layer on the surface of the heating element, the melting point of the heating element is higher than the melting point of the fixing layer; Prepare a carbon nanotube array formed on a substrate, the carbon nanotube array has a first end and a second end opposite to the first end, the second end is connected to the substrate; the first end of the carbon nanotube array is inserted into In the fixed layer, the fixed layer is cooled until it is solidified; the base of the carbon nanotube array is removed; and the carbon nanotube array is patterned to form a heat dissipation structure on the surface of the heating element.

Compared with the prior art, the heat dissipation structure provided by this technical solution has the following advantages: first, the heat dissipation structure is directly fixed on the heating element, does not require thermal interface materials, has a small volume, and can be conveniently applied to various fields; , the carbon nanotubes in the heat dissipation structure exist in the form of arrays, and the longitudinal heat conduction performance of the carbon nanotubes is fully utilized. Therefore, the heat dissipation efficiency of the heat dissipation structure is high.

Description of drawings

FIG. 1 is a schematic structural diagram of a heat dissipation structure in the prior art.

FIG. 2 is a schematic cross-sectional view of the heat dissipation structure provided on the heating element provided by the embodiment of the technical solution.

FIG. 3 is a top view of FIG. 2 .

Fig. 4 is a flow chart of the method for preparing the heat dissipation structure provided by the embodiment of the technical solution.

FIG. 5 is a flow chart of the manufacturing process of the heat dissipation structure provided by the embodiment of the technical solution.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Please refer to FIG. 2 , the technical solution provides a heat dissipation structure 10 disposed on a surface 18 of a heating element 12 . The heat dissipation structure 10 includes a patterned carbon nanotube array 16 and a fixed layer 14 . The patterned carbon nanotube array 16 includes a first end 162 and a second end 164 opposite to the first end 162 . The first end 162 of the patterned carbon nanotube array 16 is arranged in the fixed layer 14, and the patterned carbon nanotube array 16 is fixed on the surface 18 of the heating element 12 by the fixed layer 14, and the patterned carbon nanotube array The second end 164 of 16 extends away from the fixed layer 14 . It can be understood that the first end 162 of the patterned carbon nanotube array 16 can also penetrate through the fixed layer 14 and directly contact the heating element 12 to improve heat dissipation efficiency.

The material of the fixing layer 14 is a thermally conductive material, including a composite material or a metal with a low melting point. The composite materials include conductive polymer composite materials, conductive ceramic composite materials or other conductive composite materials, such as plastics containing carbon nanotubes. The low-melting point metals include tin, indium, lead, antimony, silver, bismuth, and alloys or mixtures of any combination thereof, such as tin-lead alloys, indium-tin alloys, tin-silver alloys, and the like. The thickness of the fixed layer 14 should not be too thick, nor should it be too thin. If it is too thick, it will not be conducive to fully utilizing the heat dissipation performance of the carbon nanotubes in the carbon nanotube array 16. If it is too thin, it will reduce its effect on the patterned carbon nanotubes. The fixing force of the array 16 causes the carbon nanotube array 16 to fall. Preferably, the thickness of the fixing layer 14 is 0.1 mm-1 mm.

The patterned carbon nanotube array 16 includes a plurality of carbon nanotubes arranged in parallel, and the carbon nanotubes extend along the direction from the first end 162 to the second end 164 of the patterned carbon nanotube array 16, and the carbon nanotubes substantially perpendicular to the surface 18 of the fixed layer 14 . Since the first end 162 of the patterned carbon nanotube array 16 is disposed in the fixed layer, the carbon nanotubes are at least partially disposed in the fixed layer 14, and the part of the carbon nanotubes exposed outside the fixed layer 14 serves as a heat dissipation fin, The heat generated by the heating element 12 is dissipated. The patterned carbon nanotube array 16 can form a predetermined pattern according to the needs of the heating element 12, and the formation of the predetermined pattern includes the following three situations: First, in the patterned carbon nanotube array 16 A part of the carbon nanotubes that expose the fixed layer 14 is removed, and the lengths of the remaining carbon nanotubes that expose the fixed layer 14 are equal to form a predetermined planar figure, such as a circle, a cross, a ring, etc.; second, the The carbon nanotubes in the patterned carbon nanotube array 16 that expose the fixed layer 14 have different lengths, forming a predetermined three-dimensional figure; third, a part of the carbon nanotubes in the patterned carbon nanotube array 16 exposes the fixed layer The portion 14 is removed, and the remaining carbon nanotubes exposed to the fixed layer 14 have unequal lengths to form a predetermined pattern. In this embodiment, in the patterned carbon nanotube array 16, the part where the fixed layer 14 is exposed by a part of the carbon nanotubes is removed, and the remaining carbon nanotubes have the same length as the part where the fixed layer 14 is exposed, as shown in FIG. 3 . The "ten" character channel. In application, the patterned carbon nanotube array 16 can increase air convection, which is beneficial to improve heat dissipation efficiency. The length of the carbon nanotubes in the patterned carbon nanotube array 16 is greater than the thickness of the fixed layer 14 . Preferably, the length of the carbon nanotubes in the patterned carbon nanotube array 16 is 0.5 mm to 5 mm. In this embodiment, the length of the carbon nanotubes in the patterned carbon nanotube array 16 is 1 mm. The carbon nanotubes in the patterned carbon nanotube array 16 are single-wall carbon nanotubes, double-wall carbon nanotubes, multi-wall carbon nanotubes or any combination thereof. The single-wall carbon nanotube has a diameter of 0.5 nanometers to 100 nanometers, the double-wall carbon nanotube has a diameter of 1.0 nanometers to 100 nanometers, and the multi-wall carbon nanotubes has a diameter of 1.5 nanometers to 100 nanometers. The distance between the carbon nanotubes in the patterned carbon nanotube array 16 is 0.1 nm-5 nm.

The specific shape of the heating element 12 is not limited, as long as it has a surface 18 for setting the fixing layer 14, the surface 18 can be a plane, or can be convex, concave or uneven. The melting point of the surface 18 of the heating element 12 should be higher than the melting point of the fixing layer 14 to ensure that the heat dissipation structure 10 will not damage the heating element when it is formed on the heating element 12 . The heating element 12 can be any heating element, including a micro device or a large device, preferably, the heating element 12 is a micro device.

Please refer to Fig. 4 and Fig. 5, the embodiment of the technical solution provides a preparation method for the above-mentioned heat dissipation structure 10, which specifically includes the following steps:

Step 1, providing a heating element 12 , the heating element 12 has a surface 18 .

The specific shape of the heating element 12 is not limited, as long as it has a surface 18 for disposing the fixing layer 14 . The melting point of the surface 18 of the heating element 12 should be higher than the melting point of the fixing layer, so as to ensure that the heat dissipation structure 10 will not damage the heating element 12 when it is placed on the heating element 12 . In this embodiment, the heating element 12 is a chip used in an integrated circuit.

Step 2, forming a molten fixing layer 14 on the surface 18 of the heating element 12 .

The fixed layer material in the molten state is arranged on the surface 18 of the heating element 12 by coating, printing, etc. to form a fixed layer 14. The material of the fixed layer 14 is a thermally conductive material. The specific material is not limited, and it can be a low melting point Metal. The low melting point metals include tin, indium, lead, antimony, silver, bismuth, and alloys or mixtures of the aforementioned materials, such as tin-lead alloys, indium-tin alloys, tin-silver-copper alloys, etc. In this embodiment, the material of the fixed layer is preferably For metallic tin.

Step 3. Prepare a carbon nanotube array 22 formed on a substrate 20 . The carbon nanotube array has a first end and a second end opposite to the first end. The second end is connected to the substrate 20 .

The specific preparation method of the carbon nanotube array 22 is not limited. The preparation method of the carbon nanotube array in the embodiment of the technical solution adopts the chemical vapor deposition method, which specifically includes the following steps: (a) providing a flat substrate 20, the substrate 20 It can be selected from glass, silicon, silicon dioxide, metal or metal oxide. The embodiment of this technical solution preferably uses a silicon dioxide substrate; (b) uniformly form a catalyst layer on the surface of the substrate 20, and the material of the catalyst layer can be iron (Fe), cobalt (Co), nickel (Ni) or an alloy of any combination thereof; (c) annealing the above-mentioned substrate 20 formed with the catalyst layer in air at 700°C-900°C for about 30 minutes-90 minutes (d) Place the treated substrate 20 in a reaction furnace, heat it to 500°C-740°C under a protective gas environment, and then pass through a carbon source gas to react for about 5 minutes-30 minutes to grow a carbon nanotube array. The carbon nanotube array is a carbon nanotube array 22 formed by a plurality of carbon nanotubes grown parallel to each other and perpendicular to the substrate 20 . The carbon nanotube array 22 includes a first end and a second end opposite to the first end, the second end is connected to the substrate 20 and fixed on the substrate 20, and the carbon nanotubes in the carbon nanotube array 22 start from the second end. One end extends toward the second end.

In the embodiment of the technical solution, the carbon source gas can be selected from acetylene, ethylene, methane and other chemically active hydrocarbons. The preferred carbon source gas in the embodiment of the technical solution is acetylene; the protective gas is nitrogen or an inert gas. Examples The preferred protective gas is argon.

It can be understood that the carbon nanotube array provided in the embodiment of the technical solution is not limited to the above-mentioned preparation method, and may also be a graphite electrode constant current arc discharge deposition method, a laser evaporation deposition method, and the like.

Step 4: Insert the first end of the carbon nanotube array 22 into the molten fixed layer 14, and cool the fixed layer 14 until it is solidified.

After inverting the first end of the carbon nanotube array 22, it is slowly inserted into the fixed layer 14 in the molten state. The depth of the carbon nanotube array 22 inserted into the fixed layer 14 is not limited, and can be adjusted according to actual conditions. The carbon nanotube array 22 can be The penetrating fixed layer 14 is in direct contact with the surface of the heating element 12 .

In order to make the carbon nanotube array 22 be inserted into the fixed layer 14 smoothly, before the carbon nanotube array 22 is inserted into the fixed layer 14, the fixed layer 14 should maintain a certain temperature so that it is in a molten state. When the carbon nanotube array 22 is inserted After being placed in the fixed layer 14, the molten fixed layer 14 is cooled at room temperature. After the fixed layer 14 is solidified, the first end of the carbon nanotube array 22 is fixed in the fixed layer 14, so that the carbon nanotubes in the carbon nanotube array 22 The tube is fixed on the heating element 12 through the fixing layer 14 . The angle formed by the carbon nanotubes in the carbon nanotube array 22 and the surface 18 of the heating element 12 is 90 degrees.

Step five, removing the base 20 of the carbon nanotube array 22 .

The substrate 20 of the carbon nanotube array 22 is removed by mechanical grinding, chemical etching, etc. In this embodiment, the substrate 20 is removed by chemical etching. It specifically includes the following steps:

First, provide an etching solution capable of dissolving the substrate. In this embodiment, the substrate 20 of the carbon nanotube array 22 is silicon dioxide, and the etching solution is selected from hydrochloric acid solution.

Second, the substrate 20 of the carbon nanotube array 22 is immersed in the corrosion solution for 30 minutes to 1 hour. In this embodiment, since the material of the substrate 20 is silicon dioxide, and the catalyst material in the carbon nanotube array 22 is metal, the substrate 20 and the catalyst are dissolved in the acidic solution during the soaking process, thereby dissolving the carbon nanotube The substrate 20 of the tube array 22 is removed, so that the second end of the carbon nanotube array 22 is detached from the substrate 20 and exposed to the air.

Optionally, finally, the first end of the carbon nanotube array 22 may be washed with an organic solvent such as alcohol or acetone.

Step 6: patterning the carbon nanotube array 22 to form a heat dissipation structure 10 on the surface 18 of the heating element 12 .

In this embodiment, the method for patterning the carbon nanotube array 22 is to irradiate the carbon nanotube array 22 with a laser beam of 1-100,000 watts/square millimeter at a speed of 800-1500 mm/s according to the path forming a predetermined pattern, A predetermined pattern is formed in the carbon nanotube array 22 .

The method for irradiating the surface of the carbon nanotube array 22 with a laser beam specifically includes the following steps:

First, a laser is provided, and the irradiation path of the laser beam of the laser can be controlled by a computer program. In this embodiment, the laser is a carbon dioxide laser.

Secondly, determine the pattern that needs to be formed in the carbon nanotube array 22, input it into the computer program, and control the laser beam in the laser to irradiate along the path that can form the pattern. By pre-determining the pattern, batch production can be realized. Conducive to industrial production.

Finally, the laser is turned on, so that a laser beam of a certain power directly irradiates some carbon nanotubes in the carbon nanotube array 22 from the front at a certain speed, forming a patterned carbon nanotube array 16 . After laser irradiation, because the high energy of the laser is absorbed by the carbon nanotubes, the high temperature generated will ablate all or part of the carbon nanotubes outside the fixed layer 14 at the laser irradiation path, so that the carbon nanotube array 22 A predetermined pattern is formed to form a patterned carbon nanotube array 16 . The patterned carbon nanotube array 16 includes a first end 162 and a second end 164 opposite to the first end 162 . The first end 162 of the patterned carbon nanotube array 16 is arranged in the fixed layer 14, and the patterned carbon nanotube array 16 is fixed on the surface 18 of the heating element 12 by the fixed layer 14, and the patterned carbon nanotube array The second end 164 of 16 extends away from the fixed layer 14 .

In this embodiment, the power density of the laser beam is 70000-80000 W/mm2, and the scanning speed is 1000-1200 mm/s. The above-mentioned laser beam power density and scanning speed are relatively large, and the carbon nanotubes can be etched at the moment when the laser beam irradiates the carbon nanotubes without causing damage to the fixed layer 14. No special requirements.

It can be understood that in this technical solution, the laser beam can also be fixed, and the movement path of the carbon nanotube array 22 can be controlled and moved by a computer program to etch a desired pattern in the carbon nanotube array 22 .

The purpose of patterning the carbon nanotube array 22 is to meet the various applications and requirements of the heat dissipation structure 10 , such as increasing the ventilation of the heat dissipation structure 10 and making full use of the heat dissipation space.

When the above-mentioned heat dissipation structure 10 is in use, when the temperature of the heating element 12 increases, the heating element 12 generates heat. Since the first end 162 of the patterned carbon nanotube array 16 is arranged in the fixed layer, the heat is transferred to the The patterned carbon nanotube array 16 dissipates the heat generated by the heating element 12 .

The heat dissipation structure provided by this technical solution has the following advantages: first, the heat dissipation structure is directly fixed on the heating element, without the need for a combination of thermal interface material and heat sink, the volume is small, and it can be conveniently applied to various fields; second, The carbon nanotubes in the heat dissipation structure exist in the form of an array, and the carbon nanotubes in the carbon nanotube array are perpendicular to the surface of the fixed layer, making full use of the longitudinal thermal conductivity of the carbon nanotubes. Therefore, the heat dissipation efficiency of the heat dissipation structure Third, the carbon nanotubes in the heat dissipation structure are used as heat dissipation fins. Since the diameter of the carbon nanotubes is very small, generally a few nanometers to tens of nanometers, a single carbon nanotube heat dissipation fin has a very large long diameter. Compared with the heat dissipation structure, the heat dissipation area of the heat dissipation structure is greatly increased, and the heat dissipation efficiency of the heat dissipation structure is improved; Fourth, since the fixed layer in the heat dissipation structure is in direct contact with the heating element in a molten state, sufficient contact can be achieved, and the heat dissipation area is increased. , therefore, the heat dissipation structure has high heat dissipation efficiency.

In addition, those skilled in the art can also make other changes within the spirit of the present invention. Of course, these changes made according to the spirit of the present invention should be included within the scope of protection claimed by the present invention.

Claims (15)

1. a radiator structure, this radiator structure is fixedly installed on a heater element surface, it is characterized in that, this radiator structure comprises a patterned carbon nano pipe array and a fixed bed, this patterned carbon nano pipe array to be fixed on this heater element by this fixed bed and directly to contact with this heater element, the material of this fixed bed is the alloy of tin, indium, lead, antimony, silver, bismuth or its combination in any, described patterned carbon nano pipe array comprises multiple carbon nano-tube, the length that the plurality of carbon nano-tube exposes fixed bed is unequal, forms predetermined pattern.

2. radiator structure as claimed in claim 1, it is characterized in that, described patterned carbon nano pipe array comprises a first end and second end relative to first end, and first end is arranged in fixed bed.

3. radiator structure as claimed in claim 2, is characterized in that, the described first end of patterned carbon nano pipe array and the surface contact of heater element.

4. radiator structure as claimed in claim 2, it is characterized in that, described patterned carbon nano pipe array comprises multiple parallel carbon nano-tube, and carbon nano-tube extends from the first end of patterned carbon nano pipe array to the second end.

5. radiator structure as claimed in claim 4, it is characterized in that, the carbon nano-tube in described patterned carbon nano pipe array is perpendicular to the surface of heater element.

6. radiator structure as claimed in claim 4, it is characterized in that, in described patterned carbon nano pipe array, the length of carbon nano-tube is 0.5 millimeter-5 millimeters.

7. radiator structure as claimed in claim 1, it is characterized in that, the material of described fixed bed is leypewter, indium stannum alloy or SAC.

8. radiator structure as claimed in claim 1, it is characterized in that, the thickness of described fixed bed is 0.1 millimeter-1 millimeter.

9. radiator structure as claimed in claim 1, it is characterized in that, the carbon nano-tube part exposing fixed bed in described patterned carbon nano pipe array is removed, and the length that remaining carbon nano-tube exposes fixed bed is unequal.

10. a preparation method for radiator structure, it comprises the following steps:

There is provided a heater element, this heater element has a surface;

Form a molten fixing layer in the surface of heater element, the material of this fixed bed is the alloy of tin, indium, lead, antimony, silver, bismuth or its combination in any;

Prepare a carbon nano pipe array and be formed at a substrate, this carbon nano pipe array comprises a first end and second end relative with first end, and the second end is connected with substrate;

The first end of above-mentioned carbon nano pipe array to be inserted in this fixed bed and directly to contact with this heater element, cooling this fixed bed and solidify to it;

The substrate of removing carbon nano pipe array; And

Carbon nano pipe array is graphical, form a radiator structure on the surface of heater element.

The preparation method of 11. radiator structures as claimed in claim 10, is characterized in that, the described method of formation one molten fixing layer in the surface of heater element comprises coating process or print process.

The preparation method of 12. radiator structures as claimed in claim 10, it is characterized in that, this fixed bed of described cooling is at room temperature to cool.

The preparation method of 13. radiator structures as claimed in claim 10, is characterized in that, the method for described removing carbon nano pipe array substrate comprises mechanical milling method or chemical etching method.

The preparation method of 14. radiator structures as claimed in claim 13, is characterized in that, the method for described employing chemical etching method removing carbon nano pipe array substrate comprises the following steps: the corrosive liquid providing a solubilized substrate; The substrate of carbon nano pipe array is immersed in this corrosive liquid and soak 30 minutes-1 hour; And, the root of washing carbon nano pipe array.

The preparation method of 15. radiator structures as claimed in claim 10, it is characterized in that, described is adopt the laser beam of 10000-100000 watt/square millimeter to irradiate carbon nano pipe array with the speed of 800-1500 mm/second according to the path forming predetermined figure by patterned for carbon nano pipe array method, forms predetermined figure in carbon nano pipe array.