JP4550613B2 - Anisotropic heat conduction material - Google Patents

Description

  The present invention relates to an anisotropic heat conductive material used in the field of electronics and the use of automobile waste heat that require effective transfer of heat generated from electronic equipment and electronic devices. As a specific example, the present invention is applied as a lower layer of a semiconductor transistor wiring layer to avoid thermal interference between transistors straddling the layers, to prevent thermal malfunction of the transistor, The present invention can be applied to increase the efficiency by reducing the thickness of the thermoelectric element. Furthermore, the present invention is applied to the conductor surface, and the waste heat generated from the conductor is not directly released to the outside, but the heat can be transferred to the target location and discharged to the target location. The present invention relates to a planar anisotropic heat conductive material that can be used for transfer and waste heat.

  When performing heat dissipation or heat transfer, heat exchange with fluid is performed by exchanging heat with liquid, heat is transferred to a material with high thermal conductivity, or evaporation or agglomeration type electric heat modules such as heat pipes are used. It was.

  When exchanging heat with fluids, the heat-evaporated and agglomerated electric heat module has restrictions on the direction, dimensions, and configuration of the heat transport path, and its performance and applications are limited. Therefore, it could not be used for cooling a device for a portable device requiring space saving. The conventional method of transferring heat using a material with high thermal conductivity has a problem that heat is released during the heat transfer process due to the low thermal insulation properties, and a sufficient amount of heat transport cannot be obtained. There is an adverse effect on the equipment due to the release and diffusion of heat.

Further, as in Patent Document 1, as a thermal insulating material, α-Si ₃ N ₄ rich phase and β-Si ₃ N ₄ rich phase are multilayered to achieve thermal insulation using phonon scattering at the heterophase interface. Methods are also being considered. This thermal insulating material has a lamination thickness of about 100 μm, which is significantly larger than the free process distance of phonons, and is a laminate of a phase with a solid solution and a phase without a solid solution. Although it is thermally insulated in the direction, it does not have high thermal conductivity in the film plane.
Non-Patent Document 1 describes theoretical considerations regarding thermal insulation in the film thickness direction by a multilayer film, but increases thermal conductivity in the film inner direction and suppresses thermal saturation from occurring in the film. There is no mention of how to do it.
Non-Patent Document 2 describes a method of using thin film formation for thermal conductivity control in a Si chip, but there is no description about the difference in thermal conductivity between the film thickness direction and the film surface direction. There is no mention of the effects of multilayering.

JP-A-8-276537 S. Tamura et. al: Physical Review B, vol38, 1427. A. A. Balandian: NASA-Ames, FEB28, 2003

  There is no material and method that can effectively extract heat generated from electronic devices and electronic equipment modules in a space-saving manner. It is an object of the present invention to prevent such problems.

  According to the present invention, an anisotropic heat conductive material capable of exhibiting thermal insulation in the film thickness direction and high heat conductivity in the film direction can be obtained by combining the thermal resonance material and the high heat conductivity material in the film. Waste heat can be transferred and effectively used. Details of the invention will be described below.

The invention according to claim 1 diffracts a part of heat input composed of a heat conductor 1 (constituent material A) for transferring heat to both the film surface and the film thickness direction and a component perpendicular to the film surface. This is an anisotropic heat conduction material that is formed by laminating the thermal resonator 2 (construction material B) exhibiting a thermal insulation characteristic, and further determines the film thickness t and heat input of the thermal resonator 2 (construction material B). large phonon wavelength λ of the wavelength distribution density C. in phonons configuration meets the following relation,
mλ / 2.2 <t <mλ / 1.8 (m is an integer)
As a combination of the constituent material A and the constituent material B, (A, B) = (Ag, Si), (C, Si), (Cu, Cr), (C, Cr), (Cu, Ru), (C, An anisotropic heat conductive material, wherein one set selected from the group consisting of Ru), (Pt, Ag), and (C, Ag) is selected .
As a result, the anisotropic heat conductivity can be expressed because the heat conductor 1 (the constituent material A) plays a role of transferring heat from the inside of the film to the end of the film, and the heat is taken out from the end. This is because the thermal resonator 2 (the constituent material B) plays a role of causing phonon resonance, significantly lowers the thermal conductivity in the film thickness direction, and has thermal insulation. That is, the phonon vibration excited by heat input is transmitted through the constituent material B and reflected at the interface with the thermal conductor 1 (the constituent material A), thereby causing the resonance of the phonon vibration in the constituent material B. The amount of heat transferred into the heat conductor 1 (the constituent material A) is limited, and plays a role of reducing the heat transfer rate in the film thickness direction. Further, the relationship between the film thickness t of the thermal resonator 2 (the constituent material B) and the phonon wavelength λ having a large wavelength distribution density during heat input is defined when the phonon wavelength is out of the above range. This is because the phonon resonance effect in (Component B) becomes very weak, the thermal insulation in the film thickness direction decreases, and as a result, an anisotropic heat conduction effect cannot be obtained.

In the invention according to claim 2, in claim 1 which is characterized in that a repeated structure consisting of at least one set structure of the combination of the material A and the material B alternately a plurality of times from one It is an anisotropic heat conduction material of description . Even when the structure of claim 1 is provided once, although the thermal insulation effect by the thermal resonator 2 (the constituent material B) is recognized, the thermal resonator 2 (the constituent material B) has the same film thickness and has a repeated structure. Furthermore, when it is provided once, the thermal insulation effect is enhanced. This is because by providing a plurality of resonating layers, the insulation in the film thickness direction can be further enhanced as compared with the case where the resonance layer is a single layer. On the other hand, when there is a range in the phonon vibration frequency excited by heat input, the film thickness of the excited phonon vibration is changed by changing the film thickness of the thermal resonator 2 (the constituent material B) that causes resonance to form a repeated structure. Since there is an effect in reducing the transmissibility in the thickness direction, that is, improving the insulation, when the phonon vibration frequency excited by heat input has a width, the film thickness of the thermal resonator 2 (the constituent material B) is reduced. It is effective to change.

  In the invention according to claim 3, the thickness of the thermal resonator 2 (the constituent material B) according to claim 1 or 2 is an acoustic wave having at least a part of the frequency of the phonon vibration excited by heat input. The feature is that the thickness of the thermal resonator 2 (the constituent material B) is smaller than the free stroke distance L of the phonon than the free stroke distance of the acoustic phonon of all frequencies of the phonon vibration excited by heat input. Is larger, the phonon vibration is scattered when traveling through the thermal resonator 2 (the constituent material B), and the resonance phenomenon is not exhibited.

  In the invention of claim 4, the crystal of the thermal resonator 2 (component material B) of the anisotropic heat conducting material according to any one of claims 1 to 3 is continuous in the film thickness direction and there is no crystal grain boundary. The feature is that when the crystal of the thermal resonator 2 (the constituent material B) is discontinuous in the film thickness direction and there is a grain boundary or the like in the film thickness direction, direct phonon scattering or grain boundary by the grain boundary is present. This is because the free path distance of the thermally excited phonon becomes very short due to the scattering caused by the interaction between the phonon and the phonon scattered by.

The invention according to claim 5 is an anisotropic structure having a structure in which at least one of the combinations of the constituent material A and the thermal resonator 2 (the constituent material B) is alternately repeated from one time to a plurality of times. As the configuration of the thermal resonator 2 (component material B) on the outermost surface of the heat conducting material, the thermal resonator 2 (component material B) is partially configured on the film surface, or the thermal resonator 2 (component material B) is The anisotropic heat conductive material according to claim 1, wherein the heat conductive material 1 (the constituent material A) is formed in the remaining portion formed on a part of the film surface.
By adopting such a configuration, both the thermal resonator 2 (the constituent material B) having a thermal insulation characteristic on the surface of the anisotropic heat conductive material and the constituent material A that transmits heat in both the film surface and the film thickness direction. Can exist. Using the material of the above configuration, the heat generating component is mounted on the heat conductor 1 (component material A), and the electronic component in the vicinity of the heat generating component is mounted on the thermal resonator 2 (component material B). The component mounting can be performed while avoiding the thermal effect on the thermal component in the vicinity of the. At this time, the surface height of the outermost thermal conductor 1 (component material A) and thermal resonator 2 (component material B) is such that only the thermal resonator 2 (component material B) is the thermal conductor 1 (component material A). However, when the film thickness is on the order of several hundreds of nanometers, the difference in height is not particularly problematic in terms of component mounting. Mask the outermost constituent material B and deposit only the constituent material A so that the thermal resonator 2 (the constituent material B) and the thermal conductor 1 (the constituent material A) form the same plane. Can be.

The invention according to claim 6 comprises at least one set of combinations of the thermal conductor 1 (component material A) and the thermal resonator 2 (component material B) on the thermal resonator 2 (component material B). 2. The anisotropic heat conductive material according to claim 1 , wherein the structure is repeated alternately from one time to a plurality of times, and the uppermost layer has a structure of the constituent material B. By adopting such a structure, a material excellent in anisotropic thermal conductivity excellent in thermal insulation characteristics in the film thickness direction can be obtained. When using an anisotropic heat insulating material to transfer heat, the anisotropic heat insulating material will transfer the required distance from the heating element to the heat dissipation part. The outermost layer was configured such that the heat conductor 1 (the constituent material A) excluding the thermal resonator 2 (the constituent material B) from the constitution of the constituent material of the heat transfer portion was the outermost layer.

In the invention according to claim 7, the heating element is brought into contact with the heat radiating member, the circuit board, or the electronic component board through the anisotropic heat conductive material according to any one of claims 1 to 6. This is a heat dissipation structure using an anisotropic heat conductive material. In order to achieve such a configuration, the laminated structure according to any one of claims 1 to 6 is formed by film formation on a heat radiating member, a circuit board, or an electronic component substrate, or a tape-shaped or tube-shaped film described later is formed. By soldering, it is possible to dissipate heat from the heat-generating component. Those that cannot be soldered, such as C, can be joined with an adhesive including a high thermal conductivity material.

  The invention according to claim 8 is the heat dissipation structure using the anisotropic heat conductive material according to claim 7, wherein the heating element is a semiconductor element or a semiconductor package. When the heating element is a package sealed with resin or ceramics, the thermal conductor 1 (component A) is made of a metal such as Ag, Cu, or Pt. In some cases, it can be performed by soldering, and in the case of non-metal such as C, bonding can be performed with a conductive adhesive or the like.

The invention according to claim 9 is a semiconductor component in which the anisotropic heat conductive material according to any one of claims 1 to 6 is integrally incorporated in a substrate. With the above-described configuration, it is possible to incorporate the semiconductor component into which the anisotropic heat conductive material is integrated.

A tenth aspect of the present invention is an electronic device component in which the anisotropic heat conductive material according to any one of the first to sixth aspects is integrally incorporated in a substrate. With the configuration as described above, it is possible to incorporate into an electronic device component in which the anisotropic heat conductive material is integrated.

The invention according to claim 11, the substrate is a motor vehicle control devices incorporating the anisotropic heat conducting material according to any one of claims 1 to 6. The anisotropic heat conductive material of the present invention can also be applied to automotive control equipment having many heat generating parts.

The invention described in claim 12 is an electric / heat transfer material that transmits both electricity and heat, in which the anisotropic heat conductive material according to any one of claims 1 to 6 is incorporated in the outer periphery of the conductive material. is there. Specifically, a material that transfers heat and electricity can be obtained by transferring electricity with the conductive material itself and transferring heat with the anisotropic heat conductive material on the outer periphery thereof.

A thirteenth aspect of the present invention is the anisotropic heat conducting material according to any one of the first to sixth aspects, wherein the anisotropic heat conducting material is formed of a tape-shaped or tube-shaped film.

  According to the present invention, it is a very thin material, has a very high thermal insulation in the film thickness direction, and can take out heat from the film end, so that it can be applied to a device in which thermal insulation is important. The waste heat extracted from the end can be used effectively. Therefore, this anisotropic heat conductive material can effectively move the heat generated from the electronic equipment and electronic device. And it can be used in the electronics field and the automobile waste heat utilization field. As a specific example, the semiconductor transistor lower wiring layer has the effect of avoiding thermal interference between transistors and preventing thermal malfunction of the transistors. The present invention can be applied to the thermoelectrode of the thermoelectric element to increase the efficiency by making the thermoelectric element thin. Furthermore, since the present invention is applied and the heat of the conductor is not directly emitted to the outside, the heat can be transferred and discharged to a target location, so that heat transfer and waste heat utilization can be performed in a small space. An anisotropic heat conducting material is obtained.

In order to form an anisotropic thermal conductive film, a thermal resonance phenomenon is caused in the constituent material B to show thermal insulation, and in the thermal conductor 1 (the constituent material A), It is important that the thermal conductivity is very high. In order for the thermal resonance phenomenon to occur in the constituent material, it is important that the thickness of the thermal resonator 2 (the constituent material B) is longer than the free stroke distance of the phonon excited by heat input. The free path distance L of the phonon is approximately expressed by the following equation depending on the thermal conductivity ω, the specific heat capacity C, and the phonon velocity V.
L = 3ω / (C ・ V)
Since the phonon velocity V is expressed by the elastic modulus M and the specific gravity ρ as V = (M / ρ) ^1/2 , the free path distance L of the phonon is L = 3ωρ ^1/2 / (C · M ^{1 /} It can be estimated in ² ). The acoustic phonon mode is involved in most of the heat transfer.

Further, the thickness of the thermal resonator 2 (the constituent material B) must be longer than the free stroke distance L and satisfy the resonance condition. The condition for causing the phonon vibration to resonate is expressed by t = mλ / 2 (m is a natural number), where t is the thickness of the thermal resonator 2 (component B), and λ is the wavelength of the phonon. . m is effective as long as t <L is satisfied. The phonon wavelength excited by heat input has a distribution, so the wavelength cannot be specified strictly. However, if the main component of the wavelength deviates greatly from the above relationship, the phonon resonance phenomenon will not be seen. It is preferable that the wavelength λ and the thickness of the thermal resonator 2 (the constituent material B) are closer to the above relationship.
The heat conductor 1 (the constituent material A) needs to have a high thermal conductivity, and in particular, it is desired that the heat conductivity in the film surface direction is superior to the film thickness direction. As a substance satisfying such conditions, a layered substance is typical, and a graphite-based material is exemplified. A material having a low elastic modulus in the film thickness direction and a high elastic modulus in the film surface direction satisfies the requirements as the heat conductor 1 (the constituent material A).

The elastic scattering efficiency that causes phonon resonance at the interface between the thermal conductor 1 (component material A) and the thermal resonator 2 (component material B) is as follows: the thermal conductor 1 (component material A) and the thermal resonator 2 (component material). B) is determined by the transmission coefficient P determined from the sound speed V and the specific gravity ρ.
_{P = 4 (M A · ρ} A) 1/2 · (M B · ρ B) 1/2 / ((M A · ρ A) 1/2 + (M B · ρ B) 1/2) 2
It is understood that a combination of the thermal conductor 1 (constituent material A) and the thermal resonator 2 (constituent material B) having the smallest possible P value obtained from this formula is preferable and determines the thermal insulation in the film thickness direction. . The scattering coefficient is preferably as small as possible in order to expect thermal insulation in the film thickness direction.

  The film formation technology of the thermal conductor 1 (constituent material A) and the thermal resonator 2 (constituent material B) is not particularly defined, but the phonon freedom that affects the characteristics of the thermal resonator 2 (constituent material B) Since the stroke distance depends on the completeness of the crystal in the film thickness direction of the thermal resonator 2 (the constituent material B), it is desirable that the method can generate a continuous crystal in the film thickness direction. Moreover, since it is preferable that the heat conductor 1 (the constituent material A) has a higher thermal conductivity in the in-film direction than in the film thickness direction, a manufacturing method in which the structure is stable in the in-film direction is preferable.

  As a crystal generation method in which a continuous crystal in the film thickness direction of the thermal resonator 2 (the constituent material B) is stably generated, there are an ion cluster beam method, an MBE method, and the like. The MBE method is desirable for stability.

  The thickness of the thermal resonator 2 (the constituent material B) is different from the Debye frequency of the phonon that is thermally excited depending on the temperature used. Therefore, the thickness of the thermal resonator 2 (the constituent material B) is changed accordingly. be able to. As the thickness of the thermal resonator 2 (the constituent material B) increases within the phonon free process distance of the constituent material B, the thermal insulation increases as the thickness increases. However, increasing the thickness causes an increase in cost. It is important to decide in consideration of the balance. In addition, the thickness of the heat conductor 1 (the constituent material A) is preferably thick from the viewpoint of increasing the thermal conductivity in the in-plane direction of the film, but the film thickness is too thick and the thickness is phonon free. Exceeding the process distance is not preferable because the frequency distribution of the phonon vibration that has passed through the thermal conductor 1 (the constituent material A) is widened and the variation in the phonon transmission direction is large.

  Although the evaluation of the thermal insulation characteristics in the thermal resonator 2 (component B) has been described in the direction perpendicular to the film surface, in reality, all phonons excited by heat input are directional components perpendicular to the film surface. In the thermal conductor 1 (the constituent material A), there are also phonons having an arbitrary angle with respect to the film surface. For example, there are many phonons having an angle θ with respect to the film surface. Although it exists, it is considered that the vertical component is taken out and the sum of these is taken.

  On the other hand, in the thermal conductor 1 (the constituent material A), when phonon reflection occurs at the interface with the thermal resonator 2 (the constituent material B), the loss is transmitted to the thermal conductor 1 (the constituent material A). It is necessary to consider the coming phonon, and the phonon having the same direction component as the phonon vibration transmitted from the thermal conductor 1 (component material A) is transmitted in the film thickness direction of the thermal conductor 1 (component material A), After passing through the inside, a part is transmitted to the adjacent thermal resonator 2 (the constituent material B), and a part is again scattered at the interface of the thermal resonator 2 (the constituent material B). The phonons scattered in the heat conductor 1 (the constituent material A) have a transmission component in the in-film direction and are therefore extracted outside the film by the heat conductive film.

  The phonons transmitted again to the thermal resonator 2 (the constituent material B) are transmitted through the material B and scattered at the interface of the thermal conductor 1 (the constituent material A), and some of the phonons are the thermal conductor 1 (the constituent material A). In the case of satisfying the reflection condition determined by the film thickness, the resonance phenomenon occurs again. By repeating this process, the phonons transmitted in the film thickness direction are converted into phonons transmitted in the in-film direction, heat extraction can be performed from the film end, and thermal insulation can be obtained in the film thickness direction.

  Optical phonons are also involved in heat transfer, but only acoustic phonons are taken into account because optical phonons are less affected by energy density and frequency and are much more affected by acoustic phonons. .

  The combination of the thermal conductor 1 (constituent material A) and the thermal resonator 2 (constituent material B) in the present invention is the thermal conductor 1 (constituent material A) and the thermal resonator 2 (constituent material) for some combinations of materials. As a result of the prediction calculation regarding B), the combination of materials shown in the examples was selected.

Example 1
Si is selected as the thermal resonator 2 (component material B), Ag and graphite C are selected as the thermal conductor 1 (component material A), and a 10 mm × 10 mm multilayer film is formed using single crystal Si (100) as a substrate. The film thickness of the thermal resonator 2 (component material B) was evaluated. The thermal resonator 2 (component material B) was formed by molecular beam epitaxy, and the heat conductor 1 (component material A) was formed by CVD or sputtering. In either case, first, the thermal conductor 1 (the constituent material A) was formed on the single crystal Si, and then the thermal resonator 2 (the constituent material B) was formed thereon, and 50 periods were formed. Table 1 shows the structure of the silicon substrate multilayer film. Further, a fine thermocouple was connected to the film end face, and the time and temperature change when the temperature rose by 5 ° C. were measured. The thermal conductivity in the film thickness direction was measured by the thermoreflectance method. The heat input was applied to a 1 mmφ region at the center of the film using a pulse laser, excited by coherent phonons, and heated. Under conditions 2, 3, 6, and 7, the thermal conductivity in the film thickness direction is very low, and it is considered that the phonon oscillation excited by heat input caused a resonance phenomenon. In addition, under the condition that the resonance phenomenon is considered to occur, heat transfer in the in-film direction is accelerated, and the thermal conductivity in the film surface direction is considered to be improved.

(Example 2)
The material obtained by forming Ag / Si on the single-crystal Si having a thickness of 500 microns shown in Example 1 and the single-crystal Si having a thickness of 500 microns are used as the thermoelectrode of the thermoelectric element made of BiTe semiconductor. Measurements were made. The distance between the hot electrodes was 1.2 mm. The thermoelectric conversion efficiency of the thermoelectric element when an Ag / Si film formed on Si is used as the thermoelectrode was 35%, whereas the thermoelectric conversion efficiency when the Si single crystal film was used. Only 15%. From the above, the present invention is considered to have a great effect on increasing the efficiency of thermoelectric elements.

(Example 3)
Si is selected as the thermal resonator 2 (component material B), Ag and graphite C are selected as the thermal conductor 1 (component material A), and a 10 mm × 10 mm multilayer film is formed using single crystal Si (100) as a substrate. The same method as in Example 1 was used. The difference from Example 1 is that the influence of the number of laminations of the thermal resonator 2 (the constituent material B) and the thermal conductor 1 (the constituent material A) on the Si substrate is observed. Further, a fine thermocouple was connected to the film end face, and the time and temperature change when the temperature rose by 5 ° C. were measured. The thermal conductivity in the film thickness direction was measured by the thermoreflectance method. The heat input was applied to a 1 mmφ region at the center of the film using a pulse laser, excited by coherent phonons, and heated. In the material (Conditions 32, 33, 35, and 36) in which the thermal conductor 1 (the constituent material A) and the thermal resonator 2 (the constituent material B) are stacked a plurality of times, the thermal conductivity in the film thickness direction was repeated for one period layer. Compared with the conditions 31 and 34, it is very low. The reason for this is considered to be that the heat transfer coefficient in the film thickness direction is significantly reduced by the effect of stacking a plurality of times. In addition, in 31 and 34, although the resonance phenomenon was recognized, it took time to change the temperature at the end, but the heat capacity of the thermocouple was large with respect to the total heat input, and it took time to increase the temperature. It seems to be.

Example 4
Cr is selected as the thermal resonator 2 (component material B), Cu and graphite C are selected as the thermal conductor 1 (component material A), and a 10 mm × 10 mm multilayer film is formed using the (111) oriented Cu plate as a substrate. Configured. The thermal resonator 2 (component material B) was formed by molecular beam epitaxy, and the heat conductor 1 (component material A) was formed by CVD or sputtering. In any case, first, the constituent material A was formed on the oriented Cu substrate, and then the thermal resonator 2 (the constituent material B) was formed thereon, and 50 periods were prepared. Table 3 shows the structure of the Cu substrate multilayer film. Further, a fine thermocouple was connected to the film end face, and the time and temperature change when the temperature rose by 5 ° C. were measured. The thermal conductivity in the film thickness direction was measured by the thermoreflectance method. The heat input was applied to a 1 mmφ region at the center of the film using a pulse laser, excited by coherent phonons, and heated. Under the conditions of 38, 39, 42, and 43, the thermal conductivity in the film thickness direction is very low, and it is considered that the phonon vibration excited by heat input caused a resonance phenomenon. In addition, under the condition that the resonance phenomenon is considered to occur, heat transfer in the in-film direction is accelerated, and the thermal conductivity in the film surface direction is considered to be improved.

(Example 5)
Ru is selected as the thermal resonator 2 (constituent material B), Cu 2 and graphite C are selected as the thermal conductor 1 (constituent material A), and a 10 mm × 10 mm multilayer film is formed using the (100) oriented Cu plate as a substrate. Configured. The thermal resonator 2 (component material B) was formed by molecular beam epitaxy, and the heat conductor 1 (component material A) was formed by CVD or sputtering. In any case, first, the thermal conductor 1 (the constituent material A) was formed on the oriented Cu substrate, and then the thermal resonator 2 (the constituent material B) was formed thereon, and 50 periods were prepared. Table 4 shows the structure of the Cu substrate multilayer film. Further, a fine thermocouple was connected to the film end face, and the time and temperature change when the temperature rose by 5 ° C. were measured. The thermal conductivity in the film thickness direction was measured by the thermoreflectance method. The heat input was applied to a 1 mmφ region at the center of the film using a pulse laser, excited by coherent phonons, and heated. Under the conditions 46, 47, 50 and 51, the thermal conductivity in the film thickness direction is very low, and it is considered that the phonon vibration excited by heat input caused a resonance phenomenon. In addition, under the condition that the resonance phenomenon is considered to occur, heat transfer in the in-film direction is accelerated, and the thermal conductivity in the film surface direction is considered to be improved.

(Example 6)
Ag is selected as the thermal resonator 2 (component material B), Pt and graphite C are selected as the thermal conductor 1 (component material A), and a (100) oriented Fe plate is used as a substrate to form a 10 mm × 10 mm multilayer film. Configured. The thermal resonator 2 (component material B) was formed by molecular beam epitaxy, and the heat conductor 1 (component material A) was formed by CVD or sputtering. In either case, first, the thermal conductor 1 (the constituent material A) was formed on the single crystal Fe, and then the thermal resonator 2 (the constituent material B) was formed thereon, and 50 periods were formed. Table 3 shows the structure of the Fe substrate multilayer film. Further, a fine thermocouple was connected to the film end face, and the time and temperature change when the temperature rose by 5 ° C. were measured. The thermal conductivity in the film thickness direction was measured by the thermoreflectance method. The heat input was applied to a 1 mmφ region at the center of the film using a pulse laser, excited by coherent phonons, and heated.
In any of the samples, no resonance phenomenon was observed, and the thermal conductivity tended to be high in the film thickness direction. Moreover, since heat penetrates in the film thickness direction, the heat conductivity in the in-film direction was not significantly changed even in the laminated state.

  FIG. 1 is a schematic diagram showing the effect of the anisotropic heat conductive material. FIG. 1 shows a thermal insulation characteristic by causing a diffraction phenomenon with respect to a heat conductor 1 (constituent material A) that transfers heat in both directions of a film surface and a film thickness and heat input 3 composed of components perpendicular to the film surface. It has a structure in which the illustrated thermal resonator 2 (the constituent material B) is alternately repeated a plurality of times. Here, the thickness of the thermal resonator 2 (the constituent material B) for the purpose of causing a resonance phenomenon is slightly changed for each layer. Here, the film thickness of the thermal resonator 2 (the constituent material B) differs in the resonance frequency (frequency) depending on the temperature region of the heat input 3 that causes diffraction. The higher the heat input 3, the higher the resonance frequency and the shorter the wavelength, and the lower the heat input 3, the lower the resonance frequency and the longer the wavelength.

  In FIG. 2, a part of the thermal resonator 2 (component material B) of the anisotropic heat conductive material on the surface layer in the configuration of FIG. 1 is replaced with the heat conductor 1 (component material A), and a heating element 5 is laminated thereon. Alternatively, a configuration in which a part of the thermal resonator 2 (the constituent material B) on the surface layer in the bonded configuration and the configuration in FIG. By setting it as such a structure, both can escape efficiently the heat | fever of a heat generating body through the heat conductor 1 (construction material A) efficiently elsewhere. FIG. 3 shows a configuration in which the anisotropic heat conductive film 6 is connected by the heat generator 5 and the heat radiator 7 to release heat. With the configuration as shown in FIG. 3, heat can be efficiently released from the heating element 5 to the radiator 7.

  FIG. 4 shows an example of application to heat extraction into a semiconductor chip in the case of a three-gate transistor. In this example, an anisotropic heat conductive film is formed on a Si substrate, and a back gate Si film and a silicon oxide substrate 13 are further formed thereon to form a three-gate transistor 8. Heat generated in the transistor is extracted outside the chip through the anisotropic heat conductive film 6. Further, the heat escaping to the upper part of the transistor can be extracted to the outside of the chip by the anisotropic heat conductive film 6 formed in the upper wiring layer, and thermal interference between the wiring layers can be avoided. It can handle high density wiring.

  5 and 6 show two schematic diagrams of high-efficiency thermoelectric elements. By using the anisotropic heat conductive film 14 and the anisotropic heat conductive film 6 in the heat electrode portion for transferring heat, the electrodes are alternately sandwiched between the N-type semiconductor 15 and the P-type semiconductor 16 between the electrodes 17 (heat electrodes). If the distance between the electrodes 17 (thermal electrodes) is very small, the thermal interference between the electrodes 17 (thermal electrodes) is small and can be made very thin. Obtainable.

Schematic diagram showing the effect of anisotropic heat conduction material Application examples for heat extraction in semiconductor chips High efficiency heat conduction element structure Example of application of anisotropic heat conduction film to 3-gate transistor High efficiency heat conduction element structure A High efficiency heat conduction element structure B

Explanation of symbols

1. Thermal conductor (component A)
2. Thermal resonator (component B)
3. Heat input4. Transmission heat Heating element 6,14. 6. Anisotropic heat conductive film 8. Heat radiator 8.3 Gate transistor Source 10 Drain 11. Silicon body 12. Polycrystalline silicon electrode 13. 15. Back gate Si film and oxide substrate, or Back gate Si film and insulating substrate N-type semiconductor 16. P-type semiconductor 17. Electrode 18. Insulating substrate 20. Heat transfer direction in the heat conductor film surface

Claims (13)

Laminating component material A that transmits heat to both the film surface and the film thickness direction, and component material B that exhibits thermal insulation characteristics by causing a diffraction phenomenon to occur in part of heat input composed of a component perpendicular to the film surface an anisotropic heat conducting material formed by further constituent material thickness t and large phonon wavelength of distribution density in the phonon constituting the heat input λ and B meet the following relationship,
mλ / 2.2 <t <mλ / 1.8 (m is an integer)
As a combination of the constituent material A and the constituent material B, (A, B) = (Ag, Si), (C, Si), (Cu, Cr), (C, Cr), (Cu, Ru), (C, An anisotropic heat conductive material, wherein one set selected from the group consisting of Ru), (Pt, Ag), and (C, Ag) is selected . 2. The anisotropic heat conducting material according to claim 1, wherein the structure composed of at least one of the combinations of the constituent material A and the constituent material B has a structure in which the structure is alternately repeated once to plural times.   3. The anisotropic heat conducting material according to claim 1 or 2, wherein the thickness of the constituent material B is smaller than the free path distance L of acoustic phonons of at least some frequencies in the phonon vibration excited by heat input. An anisotropic heat conducting material characterized in that.   The anisotropic heat conductive material according to any one of claims 1 to 3, wherein the crystal of the constituent material B is continuous in the film thickness direction and there is no crystal grain boundary. As a configuration of the constituent material B on the outermost surface of the anisotropic heat conducting material having a configuration in which the configuration consisting of at least one of the combinations of the constituent material A and the constituent material B is alternately repeated from one time to a plurality of times, the configuration 2. The structure according to claim 1, wherein the material B is partially formed on the film surface, or the structure material A is formed on the remaining part of the film material B formed as a part of the film surface. Thermally conductive material. A structure consisting of at least one of the combinations of the constituent material A and the constituent material B on the constituent material B is repeated one to several times, and the uppermost layer is a constituent material B. The anisotropic heat conductive material according to claim 1 . An anisotropic heat-conducting material , wherein the heat-generating member is brought into contact with the heat-dissipating member, circuit board, or electronic component substrate via the anisotropic heat-conducting material according to any one of claims 1 to 6. Heat dissipation structure using   The heat dissipation structure using the anisotropic heat conductive material according to claim 7, wherein the heating element is a semiconductor element or a semiconductor package. The semiconductor component which integrated the anisotropic heat conductive material in any one of Claims 1-6 in the board | substrate integrally. An electronic device component in which the anisotropic heat conductive material according to any one of claims 1 to 6 is integrally incorporated in a substrate. The control apparatus for motor vehicles which incorporated the anisotropic heat conductive material in any one of Claims 1-6 in the board | substrate. An electric / heat transfer material that transmits both electricity and heat, wherein the anisotropic heat conductive material according to any one of claims 1 to 6 is incorporated in an outer peripheral portion of the conductive material. The anisotropic heat conductive material according to any one of claims 1 to 6 , wherein the anisotropic heat conductive material is formed of a tape-shaped or tube-shaped film.

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