JP2011054793A - Heat spreader, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-quality heat spreader simplified in a process, and reduced in processing cost; and to provide a method of manufacturing the same. <P>SOLUTION: This heat spreader 10 includes: a metal matrix composite material layer 12 for dissipating heat of the inside of a semiconductor element 3; and a metal material layer 11 arranged to cover a surface other than a surface in contact with the semiconductor element 3 out of the metal matrix composite material layer 12. In the metal matrix composite material layer 12, particles of a thermally-conductive material having a thermal conductivity of ≥200 W/mK are dispersed in particles of a metal material constituting the metal material layer 11. This method of manufacturing the heat spreader 10 includes processes of: processing a region at a predetermined depth from a part of one main surface of a metal material member; supplying the thermally-conductive layer into the region; and agitating the thermally-conductive material into the metal material member to form the metal matrix composite material layer 12 by rotating a rotation member in the state where the rotation member is brought into contact with the thermally-conductive material. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a heat spreader and a method for manufacturing the heat spreader, and more particularly to a heat spreader used for heat dissipation of a semiconductor device and a method for manufacturing the heat spreader.

  As personal computers and mobile electronic devices have higher functionality and higher density mounting, the heat generation per unit area of heat generating parts such as CPU, GPU, chipset, and memory chip has increased dramatically. High performance is required. This is because the semiconductor element (semiconductor device) has an operating upper limit temperature specific to the semiconductor material to be configured, and the element is destroyed above that temperature. That is, when the heat radiation is insufficient, the life is significantly reduced. For this reason, it is requested | required that the thermal radiation apparatus used for a semiconductor device thermally radiates with high efficiency.

  Normally, natural convection or forced convection using an electric blower is used to radiate heat, but in principle, the amount of heat radiated per unit area has an upper limit specific to the cooling method. Therefore, in general, in order to dissipate a large amount of heat, a heat dissipating device called a heat spreader that expands the heat dissipating area is used. Specifically, a composite material based on a metal such as Al or Cu having a larger surface area than the main surface of the semiconductor element, such as an Al-SiC composite material or a Cu-diamond composite material, on the heat dissipation surface of the semiconductor device A composite material of a semiconductor material constituting the semiconductor element and a material having a close thermal expansion coefficient and excellent in heat dissipation is brought into contact. In this way, the heat spreader sucks up the heat of the semiconductor device and spreads it in the in-plane direction of the heat dissipation material. Here, the main surface means a main surface having the largest area.

  As described above, the heat spreader can widen a region where the heat generated by the semiconductor device is dissipated, so that the amount of heat generated in each region constituting the heat spreader can be reduced. Furthermore, a method may be used in which heat of the heat spreader is transferred to a cooling material formed of a metal material such as Al or Cu, for example, a heat sink to dissipate heat.

  In order to explain this more easily, FIG. 14 below is a schematic cross-sectional view showing an aspect of a heat spreader and a heat sink that are conventionally used. As shown in FIG. 14, the heat spreader 2 is disposed on one main surface of the heat sink 1, and the semiconductor element 3 is disposed on one main surface of the heat spreader 2. That is, the heat spreader 2 is arranged so as to come into contact with the semiconductor element 3 as a semiconductor device which is a heat generating component. The width in the left-right direction in FIG. 14 indicates the size of one main surface of the semiconductor element 3 or the heat spreader 2. As shown in FIG. 14, the size of the main surface of the heat spreader 2 that contacts the semiconductor element 3 is The size of the main surface of the semiconductor element 3 that contacts the heat spreader 2 is larger. As described above, by using the heat spreader 2 having a surface area larger than that of the semiconductor element 3, it is possible to widen a region where the heat of the semiconductor element 3 is radiated. For this reason, the emitted-heat amount of each area | region which comprises the heat spreader 2 can be made small. Furthermore, the heat of the heat spreader 2 can be transmitted to the heat sink 1 for cooling or dissipating heat to dissipate heat.

  Here, it is preferable to use the heat spreader 2 having a thermal expansion coefficient close to that of the semiconductor element 3. There is a large difference in thermal expansion coefficient between the semiconductor element 3 and the coolant made of the metal material constituting the heat sink 1. Because. That is, if the semiconductor element 3 is laminated as it is on one main surface of the heat spreader 2, thermal stress is generated at the interface between the two under a temperature cycle, the semiconductor element 3 is distorted, and the device does not operate stably. Or, in the worst case, cracks may be generated or peeled off at the interface, or the semiconductor element 3 may be destroyed. For this reason, the heat spreader 2 having a thermal expansion coefficient intermediate between the thermal expansion coefficients of the metal constituting the heat sink 1 and the semiconductor material constituting the semiconductor element 3 is interposed.

  These heat spreaders 2 often have a particle-dispersed structure, and the thermal expansion coefficient is determined by the volume content of particles having high thermal conductivity contained in the composite material constituting the heat spreader. Therefore, the composition is adjusted and manufactured so as to have an appropriate value between the thermal expansion coefficients of the semiconductor element 3 and the heat sink 1. These heat spreaders 2 are joined to the semiconductor element 3 or the heat sink 1 through brazing or Au—Sn plating.

  In this way, the heat spreader whose composition is adjusted so as to have an intermediate value between the thermal expansion coefficients of the semiconductor material and the metal material, for example, the particles of the material having excellent thermal conductivity (thermally conductive particles) are converted into the metal material. It is formed by sintering the mixture. Alternatively, as disclosed in Japanese Patent Application Laid-Open No. 2006-108317 (Patent Document 1), a material obtained by adding and mixing thermally conductive particles into a molten metal in which a metal material such as Al or Cu is melted is rolled. A heat spreader having a desired shape can be formed by press working or the like.

JP 2006-108317 A

  However, since the above-described methods for manufacturing a heat spreader by sintering or molding all have complicated processes, the processing cost is high. In addition, in any of the manufacturing methods described above, it is necessary to perform a process of joining the formed heat spreader and the heat sink in actual use of the formed heat spreader. For this reason, there exists a problem that processing cost becomes still higher.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a high-quality heat spreader in which the process is simplified and the processing cost is reduced, and a method for manufacturing the heat spreader.

  The heat spreader according to the present invention covers a surface of the metal matrix composite material layer that dissipates heat inside the heat generating component by contacting with the heat generating component, and a surface other than the surface that contacts the heat generating component of the metal matrix composite material layer. It is a heat spreader provided with the metal material layer arrange | positioned in. In the metal matrix composite material layer, heat conductive material particles having a thermal conductivity of 200 W / mK or more are dispersed in metal material particles constituting the metal material layer.

  The metal matrix composite material layer that dissipates heat in contact with the heat-generating component of the heat spreader as described above has high consistency in thermal expansion coefficient with the semiconductor material constituting the semiconductor element. Moreover, since it arrange | positions so that the surface of the said metal matrix composite material layer may be covered, the said metal matrix composite material layer expands the range which heat transmits. That is, the metal matrix composite material layer has a role of a heat spreader used conventionally. Further, the metal material layer covering the surface of the metal matrix composite material layer has high thermal conductivity. For this reason, the said metal material layer has a role of the heat sink conventionally used. As described above, the heat spreader has both functions of a heat spreader and a heat sink that are conventionally used in a single unit. Therefore, when the heat spreader is actually used, it is not necessary to join the heat sink again.

  A heat spreader having the above characteristics can be formed with a small number of processes by using the heat spreader manufacturing method according to the present invention described later. Therefore, a heat spreader that can suppress defects such as breakage due to thermal stress in the vicinity of a contact portion with a heat-generating component such as a semiconductor element that is in contact with one main surface of the metal matrix composite material layer can be achieved with a small number of processes. It is formed. That is, a high-quality heat spreader is provided at a low cost.

In the heat spreader according to the present invention described above, it is preferable that the thermally conductive material includes at least one selected from the group consisting of SiC, Si ₃ N ₄ , BN, AlN, diamond, carbon nanotube, and carbon fiber. By disperse | distributing the particle | grains of the heat conductive material which consists of the material mentioned above in the particle | grains of the metal material which comprises a metal material layer, a metal matrix composite material layer with high consistency of a thermal expansion coefficient with a semiconductor material is easy. It is formed.

  In the heat spreader according to the present invention described above, the metal material constituting the metal material layer preferably includes at least one selected from the group consisting of Al and Cu. Al (aluminum) and Cu (copper) are excellent in workability, brazing properties, and plating properties. Moreover, it is a metal material with high thermal conductivity. Therefore, the metal material layer can be used as a portion having a role of a heat sink.

Here, the heat generating component is, for example, a semiconductor element (semiconductor device) made of a semiconductor material as described above. In this case, the difference in thermal expansion coefficient between the heat-generating component and the metal matrix composite material layer is preferably 9 × 10 ⁻⁶ / K or less, and more preferably 6 × 10 ⁻⁶ / K or less. Specifically, the semiconductor material preferably contains at least one selected from the group consisting of Si, InP, GaAs, GaN, and AlN. If a semiconductor element (semiconductor device) made of the above-described semiconductor material is bonded to the metal matrix composite material layer formed using the above-described heat conductive material or metal material, the coefficient of thermal expansion between the materials constituting both of them can be obtained. The difference can be 9 × 10 ⁻⁶ / K or less. Therefore, by relieving the thermal stress applied between the two bonded together, malfunction of the semiconductor element can be suppressed, and problems such as thermal stress breakdown can be suppressed.

  In the heat spreader according to the present invention described above, the metal matrix composite material layer preferably has a thermal conductivity of 250 W / mK or more. In this way, the metal matrix composite material layer can sufficiently function as a conventionally used heat spreader.

  The manufacturing method of the heat spreader according to the present invention described above includes a step of processing a region having a predetermined depth from a part on one main surface of a metal material member, and supplying a heat conductive material into the region. A step of rotating the rotating member in a state where the rotating member is in contact with the heat conductive material to stir the heat conductive material inside the metal material member to form a metal matrix composite material layer; A process.

  The metal material member is a member for forming the metal material layer of the heat spreader, and is made of a material containing at least one selected from the group consisting of, for example, Al and Cu similarly to the metal material layer. For example, a removal process by polishing using a cutting tool is performed on a region having a predetermined depth from a part on one main surface of the metal material member. And it fills with a heat conductive material so that the inside of the groove | channel (gap) formed by removal processing may be filled. This thermal conductive material preferably has a thermal conductivity of 200 W / mK or more. Then, the thermally conductive material is stirred so that a metal matrix composite material layer in which the thermally conductive material is mixed with the metal material member is formed.

  In this way, if the heat conductive material is mixed by stirring with a metal material member, a metal matrix composite material layer having the role of a heat spreader can be easily formed without complicated processes such as sintering and molding. be able to. In addition, if the heat conductive material for forming the metal matrix composite material layer is appropriately selected, the thermal stress at the time of contact with the semiconductor material can be reduced. Generation | occurrence | production of the thermal-stress fracture etc. in the part joined with the base composite material layer can be suppressed. Furthermore, if a metal material for constituting the metal material layer formed by stirring the heat conductive material is appropriately selected, a high-quality metal material layer having a role as a heat sink is formed.

  In the above-described heat spreader manufacturing method according to the present invention, it is preferable that the average particle diameter of the heat conductive material particles supplied to form the metal matrix composite material layer is 0.1 μm or more and 5 μm or less. Here, the average particle diameter of the particles of the heat conductive material is an average value of the diameters of the individual spheres when the particles are approximated to be spheres. By setting the average particle size of the particles of the heat conductive material within the above-described range, a high-quality metal matrix composite material layer having excellent heat conductivity can be formed with a short tact time. That is, a high-quality metal-based composite material layer that is excellent in thermal conductivity and can dissipate heat with high efficiency can be formed at low cost.

  According to the present invention, thermal stress between a semiconductor element that is a heat-generating component and a metal material layer that serves as a heat sink can be easily reduced without complicated processes such as sintering and molding, that is, at low cost. Thus, a high-quality heat spreader that is excellent in thermal conductivity and can dissipate heat with high efficiency is formed.

It is a schematic sectional drawing which shows the aspect of the structure of the heat spreader which concerns on this Embodiment, and the heat-emitting component mounted so that the said heat spreader may be contacted. It is a flowchart for demonstrating the manufacturing method of the heat spreader which concerns on this Embodiment. It is the schematic explaining the process (S10) and process (S20) of FIG. It is the schematic explaining the process (S30) of FIG. It is the schematic explaining the process (S40) of FIG. It is the schematic which shows the aspect of the rotation tool of FIG. It is the schematic explaining the process (S40) of FIG. It is the schematic explaining the aspect of the main surface which formed the gap 4 different from FIG. 4 after performing the process (S30) of FIG. It is the schematic explaining the aspect of the main surface which formed the gap 4 different from FIG. 4 after performing the process (S40) of FIG. It is the schematic explaining the aspect of the main surface which formed the gap 4 different from FIG. 4 after performing the process (S30) of FIG. It is the schematic explaining the aspect of the main surface which formed the gap 4 different from FIG. 4 after performing the process (S40) of FIG. It is the schematic explaining the aspect of the main surface which formed the gap 4 different from FIG. 4 after performing the process (S30) of FIG. It is the schematic explaining the aspect of the main surface which formed the gap 4 different from FIG. 4 after performing the process (S40) of FIG. It is a schematic sectional drawing which shows the aspect of the heat spreader and heat sink which are used conventionally.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment)
As shown in FIG. 1, a heat spreader 10 according to an embodiment of the present invention includes a metal material layer 11 and a metal matrix composite material layer 12. A heat-generating component such as the semiconductor element 3 is placed on one main surface of the metal matrix composite material layer 12. Further, the metal material layer 11 is disposed so as to cover the surface other than the surface (specifically, the upper surface in FIG. 1) of the metal matrix composite material layer 12 that is in contact with the semiconductor element 3 that is a heat-generating component. . In other words, the heat spreader 10 according to the present embodiment includes a metal material layer 11 and a groove (gap) provided in a region having a predetermined depth from a partial region of one main surface of the metal material layer 11. It is comprised from the metal matrix composite material layer 12 arrange | positioned so that it may fill. That is, here, the region where the metal material layer 11 is partially removed to form the metal matrix composite material layer 12 is a region for placing a heat-generating component such as the semiconductor element 3.

  The heat spreader 10 of FIG. 1 has a configuration in which all surfaces of the metal matrix composite material layer 12 except the one main surface (upper main surface) with which the semiconductor element 3 contacts are covered with the metal material layer 11. ing. With such a configuration, the surface area of the metal material layer 11 is larger than the surface area of the semiconductor element 3. That is, by using the metal material layer 11 having a surface area larger than that of the semiconductor element 3 as described above, it is possible to widen a region for radiating heat of the semiconductor element 3. In addition, since the metal material layer 11 has a volume larger than that of the semiconductor element 3, the amount of heat generated in each region constituting the metal material layer 11 can be reduced. However, for example, part of the left and right side surfaces other than the main surface on the upper side of the metal matrix composite material layer 12 may be exposed without being covered with the metal material layer 11.

As will be described later, the metal matrix composite material layer 12 is a group consisting of, for example, SiC (silicon carbide), Si ₃ N ₄ (silicon nitride), BN (boron nitride), AlN (aluminum nitride), diamond, carbon nanotube, and carbon fiber. The particles of the material containing at least one kind selected from the above are dispersed in the particles of the metal material containing Al or Cu constituting the metal material layer 11. Thus, the metal matrix composite material layer 12 is a composite material in which a semiconductor material such as SiC and an insulator material such as diamond are mixed in a metal material such as Al or Cu.

The semiconductor element 3 is disposed so as to be in contact with the metal matrix composite material layer 12. Therefore, it is preferable that the thermal stress based on the difference in thermal expansion coefficient between the two when they are joined is small. In other words, the semiconductor material constituting the semiconductor element 3 preferably has a difference in thermal expansion coefficient of 9 × 10 ⁻⁶ / K or less from the material constituting the metal matrix composite material layer 12. More preferably, it is 6 × 10 ⁻⁶ / K or less. In this way, the semiconductor element 3 can suppress the occurrence of thermal stress breakdown or the like in the region bonded to the metal matrix composite material layer 12. In addition, problems such as malfunction of the semiconductor element 3 can be suppressed. For this purpose, specifically, the main constituent material constituting the semiconductor element 3 is selected from the group consisting of Si (silicon), InP (indium phosphide), GaAs (gallium arsenide), GaN (gallium nitride), and AlN (aluminum nitride). It is preferable to include at least one selected.

  In the heat spreader 10 having such a configuration, the metal matrix composite material layer 12 has the role of the heat spreader 2 conventionally used as shown in FIG. 14, for example, and the metal material layer 11 has the role of the heat sink 1 in FIG. That is, the metal-based composite material layer 12 that is one component of the heat spreader 10 on which the semiconductor element 3 in FIG. 1 is placed is similar to the heat spreader 2, for example, an Al—SiC composite material, a Cu—diamond composite material, etc. It is a composite material of a semiconductor material constituting a semiconductor element and a material having a close thermal expansion coefficient and excellent heat dissipation. Similar to the heat spreader 2, the metal matrix composite material layer 12 bridges the heat that the semiconductor element 3 has to propagate to the metal material layer 11 having a larger main surface area than the semiconductor element 3 (that is, a larger heat capacity). . Thus, in order to propagate heat to the metal material layer 11 with high efficiency, the metal matrix composite material layer 12 is configured to be surrounded by the metal material layer 11 except for one direction. Accordingly, the metal matrix composite material layer 12 in FIG. 1 corresponds to the heat spreader 2 in FIG. 14, and the metal material layer 11 in FIG. 1 corresponds to the heat sink 1 in FIG.

  As described above, in the heat spreader 10 according to the present embodiment, the metal matrix composite material layer 12 is made of a material that can relieve the thermal stress in the vicinity of the junction with the semiconductor element 3, and as a heat sink with high efficiency. It is possible to propagate to the metal material layer 11. As will be described later, the heat spreader 10 is formed without complicated steps such as sintering or press molding after mixing the raw materials. Therefore, since the heat spreader 10 is easily formed by a small number of processes, it can be provided at a low cost.

  As described above, according to the present embodiment, the high-quality heat spreader 10 having excellent thermal conductivity and capable of radiating heat with high efficiency is formed at low cost.

  Below, the manufacturing method of the heat spreader 10 which can be easily formed at low cost as mentioned above is demonstrated. As shown in the flowchart of FIG. 2, a step of preparing a metal material member (S10) is first performed. Specifically, this is a step of preparing a metal material member that is a member for forming the metal material layer 11.

  Here, a rectangular parallelepiped (plate-like) metal material member 13 is prepared. The metal material member 13 is preferably made of the same metal material as that constituting the metal material layer 11 of the heat spreader 10 of FIG. 1 to be formed. Therefore, the metal material member 13 preferably includes at least one selected from the group consisting of Al and Cu, for example. Here, the metal material member 13 does not have to be a single metal of Al or Cu, and may be, for example, an Al alloy or a Cu alloy.

  Next, as shown in FIG. 2, a step (S20) of processing the metal surface is performed. Specifically, this is a process of removing a region of a predetermined depth from the surface of a part of the region on one main surface of the metal material member 13.

  Referring to FIG. 3, with respect to the region near the center in the left-right direction on the main surface on the upper side of metal material member 13 prepared in step (S10), the vertical direction (depth direction) from the main surface. The depth at is removed by polishing. In this way, a groove-like gap 4 is formed. Note that the gap 4 is formed in a substantially rectangular parallelepiped shape in FIG. However, the shape of the gap 4 is not limited to a rectangular parallelepiped shape, and may be, for example, a semi-cylindrical shape. Further, it is preferable that the region where the gap 4 is formed substantially coincides with the region where the metal matrix composite material layer 12 shown in FIG.

  Note that when the gap 4 is formed on the metal material member 13 as described above, for example, a cemented carbide made of tungsten carbide (WC) or cobalt (Co), cubic boron nitride (cBN), or the like. It is preferable to perform removal processing by turning using a cutting tool made of

  Next, as shown in FIG. 2, a step (S30) of supplying a heat conductive material is performed. Specifically, referring to FIG. 4, the gap 4 is filled by supplying powder of the heat conductive material 5 into the gap 4 formed in step (S <b> 20).

The place where the gap 4 is formed in this way and the heat conductive material 5 is supplied is a region where the metal matrix composite material layer 12 is finally formed. Accordingly, the thermal conductive material here has a thermal expansion coefficient close to that of the semiconductor material constituting the heat-generating component (semiconductor element 3: see FIG. 1) placed on the metal matrix composite material layer 12 to be finally formed. Is preferred. This is because the metal matrix composite material layer 12 having a high thermal expansion coefficient consistency with the semiconductor element 3 can be easily formed. Specifically, when the semiconductor element 3 includes at least one selected from the group consisting of Si, InP, GaAs, GaN, and AlN, for example, SiC having a thermal conductivity of 200 W / mK or more as the thermally conductive material 5 It is preferable to use a material containing at least one selected from the group consisting of Si ₃ N ₄ , BN, AlN, diamond, carbon nanotube, and carbon fiber.

  Next, as shown in FIG. 2, a step (S40) of stirring the thermally conductive material is performed. Specifically, the thermally conductive material supplied so as to fill the gap 4 in the step (S30) is rotated, and the thermal conductive material and the metal material member 13 are configured using frictional force. This is a step of performing a friction stir processing for stirring the metal material to be stirred.

Referring to FIG. 5, a rotating tool 6 for rotating and stirring the thermally conductive material 5 filled in the gap 4 of the metal material member 13 in the step (S30) is prepared. As shown in FIG. 6, the rotary tool 6 includes a substantially cylindrical main body 7 and a probe 8. The probe 8 is a region having a smaller diameter than the main body portion 7 extending from one end portion in the longitudinal direction of the main body portion 7 in a direction along the longitudinal direction of the main body portion 7. Note that the probe 8 is not necessary for the rotary tool 6, and in some cases, the rotary tool 6 including only the substantially cylindrical main body 7 without the probe 8 may be used. An aspect in the case of using the rotary tool 6 not having the probe 8 is as shown in FIG. The material of the rotary tool 6 is, for example, a tool steel such as SKD61 steel standardized by JIS, a cemented carbide made of tungsten carbide (WC) or cobalt (Co), Si ₃ N _{4, etc.} It is preferably made of ceramics such as (silicon nitride) and cubic boron nitride (cBN).

  The rotating tool 6 shown in FIG. 6 is installed so as to abut on the gap 4 such as the bottom of the gap 4 filled with the powder of the heat conductive material 5 as shown in FIG. That is, for example, when the rotary tool 6 includes the probe 8, one end of the probe 8 (on the side opposite to the side where the main body portion 7 is disposed) is installed so as to abut on the gap 4. As shown in FIG. 6, the rotary tool 6 is rotated in a direction along a plane intersecting the longitudinal direction of the cylindrical shape while maintaining the end of the rotary tool 6 in contact with the gap 4 as described above. . In this way, the rotating tool 6 is moved in the direction along the direction in which the gap 4 extends while rotating the rotating tool 6. In this way, the powder of the heat conductive material 5 filled in the gap 4 can be stirred, and at the same time, the heat conductive material 5 can be mixed into the metal material member 13. Or conversely, the metal material member 13 can be mixed into the heat conductive material 5. In this manner, a region where the heat conductive material 5 and the metal material member 13 are mixed can be formed. Thus, the area | region where both were mixed is converted into the metal matrix composite material layer 12, as shown in FIG.

  As shown by the arrows in FIG. 5, in FIG. 5, the rotary tool 6 is moved in a direction along the direction in which the gap 4 extends while rotating. However, as shown in FIG. 7, the rotary tool 6 does not move in the direction in which the gap 4 extends, but continues to rotate at the same location, thereby mixing the powder of the heat conductive material 5 into the metal material member 13. You can also. By stirring the heat conductive material 5 as described above, the particles of the heat conductive material 5 and the particles of the metal material constituting the metal material member 13 are dispersed with each other as shown in FIG. The metal matrix composite material layer 12 which is the formed region and a metal made of the same metal material as the metal material member 13 so as to surround the metal matrix composite material layer 12 (except on the upper main surface in FIG. 7) The heat spreader 10 in which the material layer 11 is disposed can be formed.

  As described above, in order to perform the process of stirring the heat conductive material 5 in the step (S40) with high efficiency, the particles constituting the heat conductive material 5 filling the gap 4 in the step (S30) The average particle size is preferably 0.1 μm or more and 5 μm or less. If the average particle diameter exceeds 5 μm, wear of the rotary tool 6 becomes severe, and the life of the rotary tool 6 may be shortened. Also, if the average particle size is less than 0.1 μm, the metal material particles constituting the metal material layer 11 and the heat conductive material when the heat conductive material 5 is dispersed and mixed in the metal material. The area of the interface with the 5 particles increases. For this reason, in the vicinity of the interface between the metal matrix composite material layer 12 and the metal material layer 11, the thermal conductivity from the metal matrix composite material layer 12 to the metal material layer 11 may be reduced. As mentioned above, it is preferable that the average particle diameter of the particle | grains which comprise the heat conductive material 5 exists in the said range.

  The metal matrix composite material layer 12 formed by the above steps preferably has a thermal conductivity of 250 W / mK or more. In this way, the heat generated by the semiconductor element 3 placed on the metal matrix composite material layer 12 can be efficiently propagated to the metal material layer 11 and radiated. Therefore, it is preferable that the thermal conductivity is 250 W / mK or higher, and there is no upper limit to the value. Here, the heat conductivity of the metal matrix composite material layer 12 depends on the material of the metal material member 13 and the heat conductive material 5 (that is, the heat conductivity of each material constituting the heat spreader 10), and the content ratio of these materials. Dependent.

  However, when the volume occupancy ratio of particles of ceramic material such as SiC with respect to the entire metal matrix composite material layer 12 formed in the friction stir processing described above exceeds 50 mass%, the inside of the metal matrix composite material layer 12 The metal material is hardly plastically deformed. This is because the ceramic material is harder than the metal material, and if the volume occupancy of the ceramic material is increased, the hardness of the entire metal matrix composite material layer 12 to be formed is increased, so that it is difficult to be deformed. . For this reason, it is preferable that the volume content rate of the particle | grains of the ceramic material with respect to the whole metal matrix composite material layer 12 is 50 mass% or less, and it is more preferable that it is 30 mass% or less.

  By performing the processing of each step described above, the heat spreader 10 having high heat dissipation efficiency shown in FIG. 1 is formed. As described above, according to the manufacturing method according to the present embodiment, the heat spreader 10 can be formed at low cost without going through complicated steps such as sintering and molding.

  3 to 7, one gap 4 for filling the heat conductive material 5 is formed in the central portion in the left-right direction on the upper main surface of the metal material member 13. The gap 4 has a predetermined width in the left-right direction of FIGS. 3 to 7 and is formed to extend in the depth direction of the drawings. However, the gap 4 is not necessarily formed in the region shown in FIGS. For example, as shown in FIG. 8, the two left and right gaps 4 may be juxtaposed so as to extend in the depth direction on the upper main surface of the metal material member 13. In this case, when the gap 4 is filled with the heat conductive material 5 and stirred as described above, the metal matrix composite material layer 12 whose width in the left-right direction is wider than the gap 4 as shown in FIG. It is formed. In FIG. 9, the width in the left-right direction is wider than that in FIG. 8 because the particles of the heat conductive material 5 and the metal material member 13 are diffused. Similarly, for example, as shown in FIG. 10, a total of four gaps 4 may be arranged in parallel on the main surface on the upper side of the metal material member 13 so as to extend in the depth direction and the width direction. . In this case, when the gap 4 is filled with the heat conductive material 5 and stirred as described above, the metal matrix composite material layer 12 whose width in the left-right direction is wider than the gap 4 as shown in FIG. It is formed. Further, as shown in FIG. 12, for example, one gap 4 extending in the depth direction and the width direction and having a shorter length in the depth direction than that in FIG. 8 is formed on the upper main surface of the metal material member 13. Also good. Also in this case, as shown in FIG. 13, the metal matrix composite material layer 12 whose width in the left-right direction is wider than the gap 4 is formed. That is, the gap 4 can be formed in an arbitrary region on the upper main surface of the metal material member 13. However, as can be seen from comparison between FIGS. 8 and 9, FIGS. 10 and 11, and FIGS. 12 and 13, it is preferable to form the gap 4 in a region where the metal matrix composite material layer 12 is to be formed.

  As described above, the thermal shock resistance of the bonded portion when the semiconductor element 3 is bonded onto the metal matrix composite material layer 12 of the heat spreader 10 of the present embodiment, and the metal material member 13 constituting the metal matrix composite material layer 12. A test was conducted to compare the thermal shock resistance of the joint when the semiconductor element 3 was joined. Details will be described below.

  As samples for the test, samples A1, A2, A3, and A4 in which the semiconductor element 3 was bonded onto the metal matrix composite material layer 12 of the present embodiment shown in FIG. 1 were prepared. For comparison, samples B1 and B2 in which the semiconductor element 3 was bonded onto the metal material member 13 (see FIGS. 3 to 5) constituting the metal matrix composite material layer 12 were prepared. Table 1 below shows the materials and characteristics of the constituent elements of Samples A1 to A4 and Samples B1 and B2, the tools used, and the test results.

As shown in the column of “Semiconductor element” in Table 1, as the semiconductor element 3 used for each sample, an element using InP as a semiconductor material is used for samples A1, A2, and B1, and Si is used for samples A3, A4, and B2. An element using a semiconductor material was prepared. These elements are squares with a main surface of 1 mm × 1 mm, and have a rectangular parallelepiped shape (flat plate shape) with a thickness of 0.25 mm, which is the distance between a pair of opposing main surfaces. As shown in the column of “thermal expansion coefficient of semiconductor element” in Table 1, the thermal expansion coefficient of InP at 20 ° C. is 4.3 × 10 ⁻⁶ / K, and the thermal expansion coefficient of Si at 20 ° C. is 3 2 × 10 ⁻⁶ / K. Although not described in Table 1, an element using GaAs and GaN as a semiconductor material was also used as the semiconductor element 3 in addition to this.

  A metal material constituting the metal material member 13 (see FIGS. 3 to 5) as the metal material layer 11 of FIG. 1 or the metal material members 13 of the samples B1 and B2 for forming the samples A1 to A4 is displayed. 1 is shown in the column of “Metal material member”. As shown in Table 1, Cu is used as a metal material for samples A1, A2, and B1. On the other hand, for samples A3, A4 and B2, Al is used as the metal material. As shown in the column of “Thermal conductivity of metal material member” in Table 1, the thermal conductivity of Cu is 395 W / mK, and the thermal conductivity of Al is 235 W / mK. These metal material members have a rectangular shape (flat plate shape) having a main surface of a square of 100 mm × 100 mm and a thickness of 5 mm which is a distance between a pair of opposed main surfaces.

  Here, the metal matrix composite material layers 12 (see FIG. 1) of the samples A1 to A4 are formed according to the procedure shown in the flowchart of FIG. That is, after preparing the metal material member 13 having the above-described material and size in the step (S10) of FIG. 2, one main surface of the metal material member 13 is shown in FIG. 3 in the step (S20) of FIG. Thus, a gap 4 having a width of 1 mm, a depth of 100 mm, and a depth of 2 mm is formed in the central portion (with respect to the left-right direction) of the main surface. Here, the cutting tool used in the process of forming the gap 4 is shown in the “Tool” column of Table 1. The gap 4 was formed using a cutting tool made of cemented carbide for the sample A1 and a cutting tool made of cBN for the samples A2, A3 and A4.

Then, in the step (S30) of FIG. 2, the gap 4 was filled with the heat conductive material 5. The material of the heat conductive material 5 filled in each sample is shown in the column of “particles of heat conductive material” in Table 1. As shown in Table 1, SiC particles were filled in samples A1 and A2, and diamond particles were filled in samples A3 and A4. The average particle diameter of each particle filled in each sample is shown in the column “average particle diameter” in Table 1.

  Next, in the step (S40) of FIG. 2, a friction stir process was performed on the thermally conductive material 5 using the rotary tool 6 of FIG. 6 as shown in FIG. 5 and FIG. The rotary tool 6 used here has a length of 1.75 mm in the vertical direction (extending direction) of the probe 8 and a circular diameter of 3.8 mm intersecting the extending direction. The length of the current direction) is 30 mm, and the circular diameter intersecting the extending direction is 12 mm. In performing the friction stirring process, the rotation speed of the rotary tool 6 was 1400 rpm, and the speed at which the rotary tool 6 moved in the direction in which the gap 4 extends (the depth direction in FIGS. 3 to 5) was 45 mm / min.

  In this way, a sample corresponding to the heat spreader 10 for the samples A1 to A4 was formed. The entire surface of the heat spreader 10 on which these metal matrix composite material layers 12 are formed is removed by polishing for a depth of about 0.1 mm so that the center line average roughness Ra of the surface of the heat spreader 10 becomes 0.05 mm. I made it.

Subsequently, only the metal matrix composite material 12 portion of the formed heat spreader 10 was cut out and taken out. Then, the density of the metal matrix composite material layer 12 is measured by the Archimedes method, and the volume content of the ceramic material particles with respect to the entire metal matrix composite material layer 12 is calculated with reference to the true density value of the metal material member 13 and the like. did. The result is shown in the column “Content of metal-based composite material layer” in Table 1. Further, in the right column, “thermal conductivity of metal matrix composite material layer” and “thermal expansion coefficient of metal matrix composite material layer” are listed in this order. And the column of “thermal expansion coefficient difference” on the right shows the difference in thermal expansion coefficient at 20 ° C. of the materials constituting each of the semiconductor elements 3 and the metal matrix composite material layer 12 of the samples A1 to A4. ing.

  On the other hand, for the samples B1 and B2 for comparison, since the metal matrix composite material layer 12 is not formed by the friction stir processing, the columns from “tool” to “thermal conductivity of metal matrix composite material” are blank. It is said. Accordingly, the thermal expansion coefficients of the respective metal material members 13 are listed in the column of “Thermal expansion coefficient of the metal matrix composite material layer” in Table 1, and the difference in thermal expansion coefficients between the metal material member 13 and the semiconductor elements 3 of B1 and B2. Is shown in the column of “difference in thermal expansion coefficient” in Table 1.

  The main surface of the semiconductor element 3 was joined to the main surfaces of the metal matrix composite material layer 12 for the samples A1 to A4 and the metal material member 13 for the samples B1 and B2 formed as described above. Specifically, after applying an active silver brazing paste (melting point 780 ° C.) for a thickness of about 3 μm to the main surface of the semiconductor element 3, the main surface of the metal matrix composite material layer 12 or the metal material member 13 is applied at 850 ° C. Joined by vacuum brazing. Thus, samples A1 to A4 and B1 to B2 were formed.

  These samples were put into a furnace and the durability of the brazed joint portion of the semiconductor element 3 by adding a temperature cycle was tested. Specifically, after the furnace temperature was heated to 700 ° C. at a heating rate of 10 ° C./min, the state at 700 ° C. was maintained for 1 minute. Thereafter, each sample was taken out from the furnace and immediately put into water at room temperature. Such a temperature cycle of temperature increase and decrease is repeatedly given up to 30 times, and after completion of each temperature increase and decrease, a part of the sample is cut, and the semiconductor element 3 and the metal matrix composite material layer 12 (metal material member) 13) The interface which was brazed and joined was observed using a stereomicroscope. However, when it was confirmed by observation of the interface that the brazed portion was peeled off, the test for adding the temperature cycle was completed. The number of times the temperature cycle is added before peeling occurs is shown in the column “Number of temperature cycles” in Table 1. However, since the temperature cycle addition was completed at a maximum of 30 times, the sample A4 did not peel even after the 30 temperature cycles were added.

  From Table 1, the joining part of the metal matrix composite material layer 12 (samples A1 to A4) and the semiconductor element 3 according to the present embodiment is the metal material member 13 for comparison (samples B1 to B4) and the semiconductor element. It can be seen that it can withstand a number of temperature cycles more than the junction with No. 3. The metal matrix composite material layer 12 bonded to the semiconductor element 3 in the samples A1 to A4 is made of particles of a heat conductive material such as SiC having a small difference in thermal expansion coefficient from the semiconductor material constituting the semiconductor element. Mixing. For this reason, since the difference in thermal expansion coefficient between the metal matrix composite material layer 12 and the semiconductor element 3 is smaller than the difference in thermal expansion coefficient between the metal material member 13 and the semiconductor element 3, the thermal stress at the junction between the two is reduced. it is conceivable that. This can also be seen from the fact that the smaller the value of “thermal expansion coefficient difference” in Table 1, the greater the number of temperature cycles.

  As described above, the embodiments and examples of the present invention have been described. However, the embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. It is. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention is easy without passing through complicated steps such as sintering and molding, that is, at low cost, the thermal stress with the semiconductor element that is a heat-generating component and the metal material layer that serves as a heat sink is relieved, It is particularly excellent as a technique for forming a high-quality heat spreader that has excellent thermal conductivity and can dissipate heat with high efficiency.

  DESCRIPTION OF SYMBOLS 1 Heat sink, 2,10 Heat spreader, 3 Semiconductor element, 4 Gap, 5 Thermal conductive material, 6 Rotating tool, 7 Main body part, 8 Probe, 11 Metal material layer, 12 Metal matrix composite material layer, 13 Metal material member.

Claims (10)

A metal matrix composite material layer that dissipates heat inside the heat generating component by contacting with the heat generating component;
Of the metal matrix composite material layer, a heat spreader comprising a metal material layer disposed so as to cover a surface other than the surface in contact with the heat-generating component,
The metal matrix composite material layer is a heat spreader in which particles of a heat conductive material having a thermal conductivity of 200 W / mK or more are dispersed in particles of a metal material constituting the metal material layer. 2. The heat spreader according to claim 1, wherein the thermally conductive material includes at least one selected from the group consisting of SiC, Si ₃ N ₄ , BN, AlN, diamond, carbon nanotube, and carbon fiber.   The heat spreader according to claim 1 or 2, wherein the metal material includes at least one selected from the group consisting of Al and Cu.   The heat spreader according to claim 1, wherein the heat generating component is made of a semiconductor material. The heat spreader according to claim 4, wherein a difference in thermal expansion coefficient between the semiconductor material and the metal matrix composite material layer is 9 × 10 ⁻⁶ / K or less. The heat spreader according to claim 4 or 5, wherein a difference in thermal expansion coefficient between the semiconductor material and the metal matrix composite material layer is 6 x ^10-6 / K or less.   The heat spreader according to any one of claims 4 to 6, wherein the semiconductor material includes at least one selected from the group consisting of Si, InP, GaAs, GaN, and AlN.   The heat spreader according to any one of claims 1 to 7, wherein the metal matrix composite material layer has a thermal conductivity of 250 W / mK or more. Processing a region of a predetermined depth from a part on one main surface of the metal material member;
Supplying a thermally conductive material in the region;
A step of rotating the rotating member in a state where the rotating member is in contact with the thermally conductive material to stir the thermally conductive material inside the metal material member to form a metal matrix composite material layer; A method for manufacturing a heat spreader.   The manufacturing method of the heat spreader of Claim 9 whose average particle diameter of the particle | grains of the said heat conductive material is 0.1 micrometer or more and 5 micrometers or less.

Images