WO2018190023A1 - Substrat de dissipation de chaleur, électrode de substrat de dissipation de chaleur, boîtier de semi-conducteur et module semi-conducteur - Google Patents

Substrat de dissipation de chaleur, électrode de substrat de dissipation de chaleur, boîtier de semi-conducteur et module semi-conducteur Download PDF

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WO2018190023A1
WO2018190023A1 PCT/JP2018/008075 JP2018008075W WO2018190023A1 WO 2018190023 A1 WO2018190023 A1 WO 2018190023A1 JP 2018008075 W JP2018008075 W JP 2018008075W WO 2018190023 A1 WO2018190023 A1 WO 2018190023A1
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heat dissipation
heat
metal
substrate
dissipation substrate
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PCT/JP2018/008075
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English (en)
Japanese (ja)
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福井　彰
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株式会社半導体熱研究所
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/12—Mountings, e.g. non-detachable insulating substrates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks

Definitions

  • the present invention relates to a heat dissipation substrate and a heat dissipation substrate electrode used for releasing heat generated during operation of a semiconductor device, and a semiconductor package and a semiconductor module including the heat dissipation substrate or the heat dissipation substrate electrode.
  • Semiconductor modules are widely used in various fields such as LSIs, semiconductors for radio and optical communications, power semiconductors, lasers, LEDs, and sensors.
  • Semiconductor modules equipped with semiconductor devices are advanced precision equipment that performs information processing and energy conversion, and are composed of various materials. Further, a heat dissipation substrate is used to release heat generated by the operation of the semiconductor device to the outside of the semiconductor module.
  • semiconductor devices mounted on the semiconductor modules are shifting from Si semiconductors to GaN semiconductors and SiC semiconductors having a larger band gap than Si.
  • the maximum operating temperature of conventional semiconductor devices was 125 ° C, but in recent years, the maximum operating temperature of semiconductor devices has gradually increased to 150 ° C, 175 ° C, and 225 ° C, and it operates at a maximum temperature of 250 ° C.
  • Semiconductor devices are also starting to be put into practical use.
  • a cooling system having a configuration in which a cooler (fins, cooling plates, radiators, Peltier elements, etc.) is attached to a heat dissipation board mounted on a semiconductor module and the heat of the semiconductor device is transmitted to the cooler is used.
  • a cooler fins, cooling plates, radiators, Peltier elements, etc.
  • the thermal expansion board has a linear expansion coefficient of 6.5ppm / K, which is close to the linear expansion coefficient of ceramics, but it is difficult to obtain a high thermal conductivity heat dissipation board under this restriction.
  • technology development of semiconductor packages (PKG) and semiconductor modules is allowed up to about 10 ppm / K.
  • the maximum value of the linear expansion coefficient from room temperature (RT) to 800 ° C is 10 ppm / K or less, and in the plane parallel to the surface (in the XY plane) and in the thickness direction (Z-axis direction).
  • a heat dissipation substrate having a thermal conductivity of 200 W / m ⁇ K or more at room temperature is required.
  • CuW, CuMo, CuMo-based clad structure (laminated structure) heat dissipation substrates, heat dissipation substrates made of AlSiC, etc. all satisfy these requirements.
  • the temperature of 800 ° C. is the highest temperature that can be reached in the manufacturing process of the semiconductor package.
  • the room temperature (RT) in order not to cause a problem that the heat dissipation substrate is deformed or peeled off from other members, the room temperature (RT) to 800 ° C.
  • the maximum value of the linear expansion coefficient is required to be 10 ppm / K or less.
  • a lead wire is connected to a semiconductor device placed on a heat dissipation board.
  • Power semiconductor modules are also being miniaturized, and it is difficult to secure a sufficient current carrying capacity with lead wires. Therefore, development of a heat dissipation substrate electrode in which the functions of the heat dissipation substrate and the electrode are integrated is underway.
  • IACS International Annealed Copper Standard
  • annealed standard annealed copper volume resistivity: 1.7241 ⁇ 10 -2 ⁇ m
  • the electrical conductivity of various materials is specified as a relative value to the electrical conductivity of annealed standard annealed copper. is there.
  • the heat dissipation substrate also functions as an electrode, it is required to have an electric conductivity equal to or higher than that of an Al alloy conventionally used as a lead wire, that is, 50% IACS or higher.
  • DBC Direct Bonded Copper
  • Cu Copper
  • / Ceramic / Cu and DBA (Direct Bonded Aluminum) board (Al / Ceramic / Al) soldered insulation circuit board, soldering heat dissipation board to this, and mounting a cooler with low thermal conductivity resin
  • a cooling system is used.
  • the insulated circuit board is expensive, and the size is also limited due to the convenience and economical efficiency of mounting on the semiconductor module in the same manner as the heat dissipation board.
  • ceramic materials such as AlN and Si 3 N 4 used for insulating circuit boards have a thermal conductivity that is reduced to about half of the thermal conductivity at room temperature at 250 to 300 ° C. Therefore, in order to quickly transfer heat generated during operation of the semiconductor device to the heat dissipation substrate, an insulating circuit substrate thinned to a minimum thickness that can maintain strength is used.
  • problems such as heat generation due to insufficient current carrying capacity in the Cu layer and Al layer have arisen.
  • the heat dissipation board used in the semiconductor module has (1) linear expansion coefficient, thermal conductivity, and electrical conductivity (when functioning as an electrode) according to the performance and structure of the semiconductor module, and (2) reliability. It is selected in consideration of the fact that it is possible to perform a high plating process, and (3) that operational reliability after mounting on a semiconductor module can be ensured. Whether or not it is possible to perform highly reliable plating is determined by a heat test that maintains the heat dissipation board after plating at the maximum operating temperature of the semiconductor device (for example, 250 ° C) or 400 ° C.
  • each member of the semiconductor module is determined by a heat cycle test in which the semiconductor device is repeatedly held at the maximum operating temperature (for example, 250 ° C.) and held at ⁇ 40 ° C.
  • the heat cycle test of the heat radiating substrate is very strict. If there are defects or weak parts on each member or its joint surface, the part is destroyed and rejected. In particular, these problems become more apparent as the maximum operating temperature of semiconductor devices increases.
  • the semiconductor module is mounted on a cooler, and the operation lifetime at the time of mounting the semiconductor module is determined by operating the semiconductor device by turning on / off the current at the maximum operating temperature of the semiconductor device.
  • a new heat dissipation board is manufactured by reviewing the material and structure of the heat dissipation board, and a heat dissipation board that does not cause a problem in all tests is manufactured to complete the semiconductor module.
  • the heat dissipation substrate material has been selected based on the linear expansion coefficient at room temperature or 800 ° C. and the value of thermal conductivity at room temperature.
  • semiconductor module manufacturers do not necessarily disclose information on the characteristics of the heat-dissipating substrate material of products developed by themselves, and in particular, the value of the linear expansion coefficient at the maximum operating temperature of the semiconductor device is often not disclosed. For this reason, conventionally, values of linear expansion coefficient and thermal conductivity at room temperature have been used as selection criteria.
  • ceramic package manufacturers have emphasized the value of the linear expansion coefficient at 800 ° C., which is required at the time of manufacture.
  • Semiconductor module and semiconductor package designers are searching for a material for a heat dissipation board according to the performance and structure of each semiconductor module, and developing a heat dissipation board that passes the above test.
  • the design of the semiconductor module may be reviewed so that a developable heat dissipation board can be mounted.
  • manufacturers of semiconductor modules, semiconductor packages, or heat sinks, etc. improve design by accumulating design know-how by repeatedly designing, manufacturing, simulating, and testing the semiconductor modules, semiconductor packages, and heat sinks. And developing new products.
  • the maximum operating temperature of semiconductor devices has gradually increased, and a new heat dissipation substrate that can cope with the increase in operating temperature is required.
  • the wettability of Cu and Mo is poor, and when it is manufactured by an infiltration method in which Cu is dissolved and impregnated in a Mo skeleton, or a sintering method in which Cu and Mo powder is sintered, the surface and A nest (a minute void) is generated inside. Therefore, the produced alloy was rolled to crush the nest and used as a heat dissipation substrate.
  • the pretreatment is applied to the Mo exposed on the surface to perform Ni plating (plating with Ni or Ni alloy), the Cu-Mo interface on the surface layer is eroded and the Ni plating is stable. There was a problem that it was difficult to apply.
  • the stability of the Ni-based plating process can be improved by repeating the heat treatment and the Ni-based plating process, there is a problem that the plating process becomes complicated and the cost is increased.
  • the heat dissipation substrate of the clad structure has an advantage that the thermal conductivity in the XY plane is high because a Cu layer having high thermal conductivity is provided on the surface. Furthermore, because the Cu layer on the surface of the heat dissipation substrate can be easily subjected to stable Ni-based plating treatment, the above-mentioned heat treatment and other steps are unnecessary, and it can be manufactured at a lower cost than CuMo alloys and the like. Expected.
  • the outermost layer (the outermost part of the surface layer)
  • the thermal conductivity in the Z-axis direction is low.
  • the maximum operating temperature of the semiconductor device becomes higher, defects frequently occur in the heat cycle test corresponding to the temperature. It was also found that the expected thermal conductivity could not be obtained when the operating life was tested on a semiconductor module equipped with a semiconductor device operating at 250 ° C.
  • heat dissipation substrates are manufactured by rolling, brazing, solid phase diffusion bonding (HP, hot press bonding, hot uniaxial processing, thermocompression bonding, etc.).
  • HP hot press bonding
  • thermocompression bonding etc.
  • a Mo plate-like member core base material; also referred to as “via Mo” in which holes (vias) penetrating in the thickness direction are formed.
  • Cu / via Mo / Cu three-layer heat dissipation board (hereinafter referred to as “hybrid structure”) in which Cu is introduced into the via.
  • hybrid structure Such a heat dissipation substrate with a hybrid structure, for example, melts Cu and flows it into the via to join (total melt bonding), or locally melts the interface between the via Mo and the Cu introduced into the via (bonding) ( Local melting and joining).
  • the heat dissipation board with a hybrid structure by using a core base material made of a metal having a small linear expansion coefficient such as Mo, Cu inside the via and Cu layers located on the front and back surfaces of the core base material are changed to the via Mo layer even at high temperatures. Since it is restrained and expansion and contraction are suppressed, it is expected that high thermal conductivity can be obtained while keeping the linear expansion coefficient low.
  • a core base material made of a metal having a small linear expansion coefficient such as Mo Cu inside the via and Cu layers located on the front and back surfaces of the core base material are changed to the via Mo layer even at high temperatures. Since it is restrained and expansion and contraction are suppressed, it is expected that high thermal conductivity can be obtained while keeping the linear expansion coefficient low.
  • Patent Document 1 is a document related to a heat dissipation substrate having a clad structure, in which a coating thin layer of copper, gold, silver or an alloy thereof is formed on one side or both sides of a Mo plate, and copper, nickel, gold, It is described that silver metal plates or their alloy plates are stacked and bonded by heating and pressing.
  • Patent Document 2 is a document related to a heat dissipation substrate having a clad structure, in particular, a heat dissipation substrate having a Cu / Mo / Cu clad structure or a Cu / W / Cu clad structure, and is replaced with a hot press apparatus or a hot isostatic pressure instead of a conventional rolling method. It is described that each layer is heated and pressed by a hot uniaxial machining method using a press apparatus. Specifically, Cu material and Mo material are directly overlapped, or the surface of Mo material is plated with Cu, Ni, or a combination thereof, and then Cu material and Mo material are overlapped. It is described that heat and pressure bonding is performed.
  • Patent Document 3 is also a document related to a heat dissipation substrate with a clad structure, and instead of Mo and W of a heat dissipation substrate with a Cu / Mo / Cu clad structure or a Cu / W / Cu clad structure used so far, a CuMo alloy or a CuW alloy Cu / CuMo / Cu clad structure and Cu / CuW / Cu clad structure heat dissipation substrate using the above are described. It is described that these heat dissipation boards have higher thermal conductivity in the Z-axis direction and lower linear expansion coefficient than conventional heat dissipation boards.
  • a manufacturing method is described in which a CuMo alloy or CuW alloy formed by an infiltration method or a sintering method is subjected to Ni plating, Cu is superimposed, and hot rolling or hot uniaxial pressing is performed.
  • Patent Document 4 describes a method for producing a CuMo composite alloy, in which a green compact made of Cu powder and Mo powder is prepared, and sintered, and then rolled to form a CuMo composite rolled plate. Has been.
  • Patent Document 5 discloses a multilayer clad structure heat dissipation substrate manufactured by bonding a structure formed by alternately stacking layers made of Cu or an alloy thereof and layers made of Mo or W by a hot uniaxial processing method. Is described. It is described that the thermal expansion substrate having a multilayer clad structure has a lower linear expansion coefficient than the clad structure.
  • Patent Document 6 a core base material in which a through-hole (via) penetrating in the thickness direction is formed in a plate-like member made of a material having a small linear expansion coefficient such as Invar or Mo is formed and penetrated into the inside.
  • Hybrid type heat dissipation by inserting a heat conduction member made of Cu having an outer diameter smaller than the inner diameter of the hole, and forming Cu layers on the front and back surfaces of the core substrate, and solid-phase diffusion bonding each member A substrate is described.
  • This document describes that since the gap is formed between the inner wall of the through hole, the linear expansion coefficient of the core substrate is maintained as it is even if Cu inside the through hole expands and contracts due to heat. Yes.
  • Patent Document 7 is a document describing an invention related to a hybrid heat dissipation board by the present inventor.
  • This heat dissipation board is a hybrid type heat dissipation board in which a heat transfer member made of Cu is introduced into a through hole formed in a plate-like core base material made of Mo having a small linear expansion coefficient as in Patent Document 6, Unlike Patent Document 6, they are joined by locally dissolving the interface between Mo and Cu inside the via or by flowing molten Cu into the via.
  • a large and thin heat dissipation board is prepared, and individual heat dissipation boards are manufactured by cutting out from the substrate in a predetermined size.
  • the above problem with the heat sink of the hybrid structure is that the internal structure of the heat sink of the hybrid structure is complicated. Especially in the case of a large heat sink, the gas released from the Cu dissolved inside the via remains inside the heat sink. It is presumed that this is due to variations in the internal structure of the individual heat dissipation boards.
  • one of the tests of the heat dissipation board is an operation life test when mounted on a semiconductor module.
  • This test requires a process such as mounting on a cooler and operating it, which is expensive and time consuming. . Therefore, until now, first, for a plurality of heat dissipation substrates, the linear expansion coefficient and thermal conductivity of the heat dissipation substrate alone were measured at room temperature, and only those that had the expected values were used for semiconductor packages and semiconductors.
  • the module has been manufactured and subjected to a heat cycle test, and the operating life test has been performed only on the heat dissipation board that has passed the test.
  • the requirements for the characteristics (linear expansion coefficient, thermal conductivity, electrical conductivity, etc.) of the heat dissipation board alone, and the heat in the state where it is mounted on the semiconductor package or semiconductor module It is required to have characteristics that pass the cycle test.
  • a simple test method that can determine pass / fail by the operation life test when mounting on a semiconductor module, which is expensive and time-consuming compared to other evaluation methods.
  • the inventor of the present invention has a hybrid structure heat dissipation that is expected to obtain the highest characteristics in terms of thermal conductivity, linear expansion coefficient, and electrical conductivity in the XY plane and in the Z-axis direction among the various heat dissipation substrates described above. We focused on the substrate and verified the problem.
  • Patent Document 7 when manufacturing a heat dissipation substrate having a Cu / via Mo / Cu hybrid structure, heating is performed while pressing from above and below in order to securely bond Mo and Cu inside the via. Solid phase diffusion bonding was performed. However, with this method, it was difficult to apply pressure in the direction of pushing the interface between Mo and Cu inside the via, so we thought that the bonding strength at the interface between Mo and Cu might not be sufficient. Further, as proposed in Patent Document 7, Cu in the via is locally dissolved and joined to Mo, or Cu is completely dissolved and poured into the via to join with Mo. We thought that there was a possibility that the gas generated at the time of dissolution remained inside the via, especially at the interface with Mo, causing voids.
  • Comparative Example 1 is a heat dissipation substrate having a Cu / CuMo / Cu clad structure (FIG. 1 (a)) manufactured by a rolling method.
  • Comparative Example 2 is a heat dissipation substrate having a Cu / Mo / Cu clad structure (FIG. 1 (b)) manufactured by a brazing method.
  • Comparative Example 3 is a heat dissipation substrate having a Cu / Mo / Cu clad structure (FIG. 1 (b)) manufactured by a solid phase diffusion bonding method.
  • Comparative Example 4 is a heat dissipation substrate having a Cu / via Mo / Cu hybrid structure (FIG.
  • Comparative Example 4 is a heat dissipation substrate having a Cu / via Mo / Cu hybrid structure (FIG. 1 (c)) manufactured by a local melting method. In any heat dissipation substrate, the Cu content was 66 vol%.
  • five heat dissipating substrates were prepared and the characteristics before and after the heat cycle test were evaluated. Moreover, the thing which each mounted those heat dissipation board
  • the linear expansion coefficient before the heat cycle test was 10 ppm / K or less.
  • the thermal conductivity in the XY plane and the thermal conductivity in the Z-axis direction were both 200 W / m ⁇ K or more.
  • the electrical conductivity after the heat cycle test was lower than 50% IACS in any of Comparative Examples 1 to 5.
  • Patent Document 6 also describes a heat dissipation board having a hybrid structure.
  • the heat dissipation substrate of Patent Document 6 since a gap is positively formed between the inner wall of the through hole (via), the expansion and contraction of Cu inside the via is not suppressed. Therefore, as compared with Comparative Example 4 produced by solid phase diffusion bonding as in Patent Document 6, cracks based on the voids occur in the heat cycle test of the semiconductor package and the semiconductor module, or the above-described Cu layers on the front and back surfaces It can be easily predicted that unevenness is likely to occur.
  • the problem to be solved by the present invention is to provide a heat dissipation substrate with a small decrease in thermal conductivity in the thickness direction (Z-axis direction) after the heat cycle test.
  • the present inventor believes that a change (decrease) in thermal conductivity in the thickness direction (Z-axis direction) of the heat dissipation substrate can be suitably used as a benchmark (index) for evaluating these phenomena. It was. Therefore, the inventor has a stable hybrid structure in which the decrease in the thermal conductivity in the Z-axis direction is relatively small before and after the heat cycle test of the heat dissipation substrate alone, and there is no defect in the bonding interface between Cu and Mo and the bonding strength is high. The production of a heat dissipation substrate was examined.
  • Patent Document 7 corresponding to the heat dissipation substrate of Comparative Example 5
  • the present inventor introduces Cu that has been completely melted into the Mo via or by locally melting after introducing Cu. We thought to improve the bondability with Mo. However, subsequent investigations revealed that in this case, voids may be generated inside the via due to bubbles generated from molten Cu.
  • the heat dissipation board according to the present invention is a) Ni is coated on the inner wall surface of the through hole that penetrates the plate-shaped core substrate made of Mo in the thickness direction, b) Filling the through hole with Cu in an amount corresponding to the volume of the through hole, c) A laminate is prepared by arranging plate-like heat conducting members made of Cu on the front and back surfaces of the core substrate, d) It can be manufactured by heating and pressurizing the laminate below the melting point of Cu to soften Cu and press-fit into the through-holes.
  • the amount of Cu corresponding to the volume of the via is filled in the through hole (via) of the core base material, and this is softened by heating and pressurizing to a temperature below the melting point of Cu. It is introduced (press-fitted) into the inside of the through hole while applying.
  • the interface between Mo and Cu can be pressurized and bonded firmly without gaps.
  • Cu plate-like members may be disposed on the front and back surfaces of the Mo core base material on which vias are formed, and this may be softened to press-fit Cu into the vias.
  • it is possible to press-fit Cu into the via by placing a columnar body or powder having a volume larger than that of the via into the via and softening it. Moreover, these methods can also be used together.
  • the planar shape is a rectangle, only from the side surface corresponding to a part of the outer periphery when the heat dissipation substrate after heating and pressurizing treatment is viewed in plan view Rather than press-fitting enough amount of Cu to release the joint surplus (that is, press-fitting an amount of Cu equivalent to or slightly larger than the volume of the via), the joint surplus is released on all four sides of the outer periphery. It was found that a decrease in the thermal conductivity after the heat cycle test was reduced by pressing a certain amount of Cu (that is, pressing a sufficiently larger amount of Cu than the via volume).
  • Cu is a metal that softens when heated and deforms easily when pressed. Therefore, the insertion of Cu into the via can be performed by the following method, for example.
  • the Cu plate placed on the front and back sides of the plate-like Mo core substrate on which the via is formed is heated and pressurized to press the softened Cu into the via to pressurize the interface.
  • Protrusions are provided on the surfaces of the Cu plates arranged on the front and back, and the interstices inside the vias are pressurized by inserting the protrusions into the vias.
  • Ni is coated on the inner wall surface of the via of the core substrate made of Mo to increase and stabilize the bonding strength between Cu and Mo. Since Cu is not melted by this method, Ni as an insert metal is not dissolved in Cu, and there is no fear that voids or voids are generated inside the vias of the heat dissipation board after manufacture. That is, Cu and Mo are bonded directly inside the via of the Mo core base material or in a state of being in close contact with no gap between the Ni layers.
  • a heat dissipation board with a multilayer Cu / via Mo / Cu /.../ Cu structure this is called a “multilayer hybrid structure” with an expanded hybrid structure.
  • the Mo core substrate (via Mo layer) in which the via is formed may be made thinner than the via Mo layer of the heat dissipation board of the three-layer hybrid structure. Therefore, Cu can be easily pressed into the via. Further, by arranging the positions of vias formed in each via Mo layer so as not to overlap in the upper and lower layers, even if Cu inside the via expands and contracts, the influence on the surface layer can be reduced.
  • the Cu layer located on the front and back surfaces of the heat dissipation substrate can be made thin, the effect of suppressing the thermal expansion of Cu by the via Mo layer can be enhanced, and the linear expansion coefficient in the extreme surface layer can be suppressed low.
  • the coefficient of linear expansion of Cu that constitutes the heat dissipation board is 17 ppm / K, while Mo is 5.5 ppm / K. Therefore, the degree of expansion of Cu and Mo varies greatly when the temperature of semiconductor device operation increases, and at the junction interface. A large stress is generated. Such stress generated inside the via becomes more prominent as the via Mo layer is thicker. Since a plurality of via Mo layers are provided in the multilayer hybrid structure, as described above, when manufacturing a heat dissipation substrate having the same thickness, each via Mo layer is thinner than providing only one via Mo layer. Therefore, the stress generated at the interface inside the via can be kept small.
  • the heat dissipation board according to the present invention is: a) a plate-shaped core base material made of Mo in which a through-hole penetrating in the thickness direction is formed; b) a void-free insert made of only Cu, filled in the through hole; c) a first bonding layer made of Ni and having no voids formed continuously or intermittently between the inner wall surface of the through hole and the insert; d) a void-free heat conductive layer made only of Cu formed on the front and back surfaces of the core substrate; and e) Ni formed continuously or intermittently at the interface between the core substrate and the heat conductive layer.
  • a void-free second bonding layer comprising:
  • the maximum value of the linear expansion coefficient in the temperature range from room temperature to 800 ° C is 10 ppm / K or less,
  • the thermal conductivity in the direction perpendicular to the surface at room temperature is 200 W / m
  • the heat conductivity in the direction perpendicular to the surface after performing a heat cycle test in which heating to 250 ° C. and cooling to ⁇ 40 ° C. is repeated 100 times is 200 W / m ⁇ K or more.
  • the coefficient of linear expansion is 10 ppm / K or less, and the thermal conductivity in the thickness direction after the heat cycle test is 200 W / m ⁇ K or more. Met. Further, in the heat cycle test mounted on the semiconductor package and the semiconductor module, neither the heat dissipation substrate was peeled off nor the semiconductor device was damaged.
  • the heat dissipation substrate according to the present invention when the electrical conductivity of the heat dissipation substrate according to the present invention was measured, it was also found that an electrical conductivity of 50% IACS or higher corresponding to the electrical conductivity of a lead wire made of an Al alloy was obtained. Therefore, the heat dissipation substrate according to the present invention can be suitably used as a heat dissipation substrate electrode.
  • the semiconductor package and the semiconductor module according to the present invention each include the heat dissipation substrate.
  • a heat dissipation board having a CuMo-based hybrid structure that passes the heat cycle test by improving the bondability of the interface by introducing an insert metal into the interface between Cu and Mo.
  • the problem that the thermal conductivity is lowered by dissolving different kinds of metals in the Cu by pressing the Cu in the solid phase has also been solved.
  • a heat dissipation substrate having a linear expansion coefficient of 10 ppm / K or less and having a thermal conductivity of 200 W / m ⁇ K or more in the thickness direction even after the heat cycle test was obtained.
  • good results were obtained that no peeling or breakage of each member, breakage of the semiconductor device, or the like occurred.
  • a highly reliable heat dissipation board that suppresses a decrease in thermal conductivity after heat cycle testing by press-fitting Cu in an amount that generates excess bonding (that is, press-fitting Cu in an amount greater than the via volume) can be obtained. Furthermore, in the above method, it is possible to confirm that Cu exceeding the volume of the via is press-fitted, that is, a state in which there is no void is formed inside the via, by generating a bonding surplus. Excess or deficiency of the amount of Cu injected into the interior can be easily determined from the appearance.
  • the joining process of the heat dissipation board has not been managed by the appearance of excess bonding, but for example, when manufacturing a large and thin heat dissipation board for cutting out a large number of heat dissipation boards, an appropriate position can be obtained. It is possible to manage the overall bonding quality by providing a window for checking the bonding surplus.
  • One embodiment of the manufacturing method of the heat dissipation board according to the present invention is: a) Covering the inner wall surface of the through-hole penetrating the plate-shaped core base material made of the first metal in the thickness direction, b) Filling the through hole with an insert made of a second metal having a higher thermal conductivity than the first metal, c) A laminated body is prepared by disposing a plate-like heat conductive member made of a third metal having a higher thermal conductivity than the first metal on the front surface and the back surface of the main body, d) heating and pressurizing the laminate to a temperature below the melting point of all of the first metal, the second metal, and the third metal.
  • the first metal, the second metal, the third metal, and the insert metal may be any of a single metal and an alloy. Further, the second metal and the third metal can be the same metal. In that case, for example, using a plate-like member in which a convex portion is formed at a position corresponding to the position of the through-hole, introduction of the insert into the through-hole and arrangement of the plate-like member can be performed simultaneously.
  • the inside of the through hole is covered with an insert metal having good wettability with respect to both the first metal and the second metal.
  • the joining property of the 2nd metal in the inside of a through-hole improves.
  • the said laminated body is heated and pressurized to the temperature below all melting
  • the insert metal covering the inside of the through hole is not dissolved in the first metal or the second metal. Therefore, as in the previous application by the present inventor, the melted portion in which the first metal and the second metal are alloyed is not formed at the interface inside the through hole, and the first metal and the second metal are not formed inside the through hole. In between, a layer of insert metal will be formed either continuously or intermittently.
  • one embodiment of the heat dissipation board according to the present invention is: a) a plate-shaped core base material made of a first metal having a through-hole penetrating in the thickness direction; b) an insert made of a second metal filled in the through hole and having a higher thermal conductivity than the first metal; c) a joining layer made of an insert metal, formed continuously or intermittently between the inner wall surface of the through hole and the insert, d) a heat conductive layer formed on the front and back surfaces of the main body and made of a third metal having a higher thermal conductivity than the first metal.
  • the heat dissipation substrate of the above embodiment can also be suitably used as a heat dissipation substrate electrode.
  • one embodiment of the semiconductor package and the semiconductor module according to the present invention each include the heat dissipation substrate.
  • the role of the core base material made of the first metal, which is a low linear expansion coefficient material is the heat conduction layer made of the third metal disposed on the front and back surfaces of the core base material, and the via formed in the core base material. This is to prevent the insertion body made of the second metal introduced into the inside from expanding and contracting during the operation of the semiconductor device.
  • a core base material suitable for this role for example, a material made of any of W, Mo, CuW, CuMo, In (invar), and Kv (kovar) having a linear expansion coefficient of 9.0 ppm / K or less is suitable. Can be used.
  • a core substrate made of Mo can be suitably used from the balance of both characteristics and cost.
  • the via formed in the core base material only needs to penetrate the core base material in the thickness direction, and the cross-sectional shape thereof can be appropriately determined by the manufacturer.
  • the cross-sectional shape does not necessarily have to be constant in the thickness direction, and may be, for example, a tapered shape.
  • the number, size, and arrangement of vias may be set as appropriate according to the required values of linear expansion coefficient and thermal conductivity.
  • This via can be formed by an appropriate method such as punching, etching, electric discharge machining, drilling, or the like. Moreover, you may combine these suitably.
  • the vias can be arranged in a concentrated manner at a position corresponding to a portion where the semiconductor device is easily heated.
  • the role of the insert made of the second metal is to transfer the heat from the heat conductive layer located on one surface of the heat dissipation substrate (the side on which the semiconductor device is mounted) to the other surface (such as a metal fin). It is to transmit efficiently to the heat conduction layer located on the side where the cooler is provided.
  • an insert suitable for this role for example, an insert made of a metal having a thermal conductivity of 390 W / m ⁇ K or more can be suitably used.
  • the heat dissipation board in this case is also referred to as “heat dissipation board electrode”
  • the electrical conductivity of 50% IACS or higher which is equal to or higher than the lead wire made of Al alloy. It is preferable to use one made of a metal having a rate.
  • Ag or an alloy thereof can be used in addition to Cu used in Examples described later.
  • the insert made of the second metal is inserted into the via of the core base so as to pressurize the inner wall surface (interface with the first metal) of the via of the core base in the heating and pressurizing steps described later. Therefore, it is preferable to use the second metal having a volume equal to or larger than the volume of the via as the insert.
  • “preferred” means that even if the amount of the second metal inserted into the via is slightly smaller than the volume of the via, it is disposed on the front and back surfaces of the core base material during the heating and pressurizing treatment. This is because the third metal (described later) constituting the heat conductive layer is pushed into the via to some extent, and the inside of the via is pressurized.
  • the insert has a shape that corresponds to the shape of the via and is molded higher than the depth of the via, or has an outer diameter slightly larger than the via (in this case, Cu is heated and softened to press fit)
  • powdered or granular materials can be used.
  • a convex portion having an outer diameter smaller than the inner diameter of the through-hole and higher than 1/2 of the depth of the via is formed on one surface of the heat conduction layer made of the third metal, which will be described later. Then, by softening by heating, the two convex portions can be integrated as an insert inside the via.
  • these can be used in combination as appropriate (for example, a powdery material and a convex portion formed on one surface of the plate-like member constituting the heat conductive layer can be used in combination).
  • the press-fitting of the second metal (here, Cu) into the via of the core substrate of the first metal (here, Mo) can be performed, for example, by the following method.
  • the interface is pressurized by press-fitting softened Cu inside.
  • Protrusions are provided on the surfaces of the Cu plate-like members arranged on the front and back sides, and the protrusions are inserted into the vias to pressurize the interface inside the vias.
  • Thermal conductive layer of the third metal which is a high thermal conductive material
  • the role of the heat conductive layer made of the third metal, which is a high thermal conductivity material, arranged on the front and back surfaces of the core base material increases the thermal conductivity in a plane parallel to the surface of the heat dissipation substrate (in the XY plane). That is. Moreover, it is press-fitting into the via in a softened state by heating and pressurizing and pressurizing the inside of the via. Further, as described above, a convex portion having an outer diameter that is smaller than the inner diameter of the through hole and higher than half the depth of the via is formed on one side of the heat conduction layer made of the third metal.
  • convex portions may be formed on both front and back surfaces of a plate-like member constituting the heat conductive layer.
  • a plate-like member made of Cu or Cu alloy having a thermal conductivity of 390 W / m ⁇ K or more can be suitably used.
  • a powdered material can be used, or a heat conductive layer can be formed by a thermal spraying method.
  • these can also be used in combination as appropriate.
  • a guide consisting of In particular, in the case of a multilayer clad structure, it is desirable to use such a guide because it works effectively in controlling the thickness of each heat conductive layer. Moreover, when arrange
  • the insert metal for example, Ni, Co, Cr, Ti, Zr, Hf, Nb, V, Ag, Cd, Sn, or an alloy thereof can be suitably used. A plurality of these may be used, and the joining metal layer may be multilayered. However, in many cases, since the metal simple substance has higher thermal conductivity and electrical conductivity than the alloy, the joining metal layer is preferably made of the metal simple substance. Of these, pure Ni is preferred. When a metal having a melting point lower than that of the second metal is used, it is melted when the first metal, the second metal, and the third metal are joined, and a part thereof is released to the outside as a joining surplus.
  • the bonding metal layer is for enhancing the bonding property between the first metal and the second metal, the inner wall surface of the via of the core base material made of the first metal and the second metal are formed when the heat dissipation substrate is manufactured. What is necessary is just to form in either one of the outer wall surfaces of the insertion body which consists of metals. Of course, you may form in both.
  • the bonding metal layer can be formed by an appropriate method such as plating, vapor deposition, application of metal powder, application of nano metal powder, thermal spraying, or the like.
  • the bonding metal layer 14 is formed on one or both of the front and back surfaces of the core substrate made of the first metal and the surface of the heat conductive layer made of the third metal (the surface bonded to the core substrate). Is preferred. Thereby, the joining property of a core base material and a heat conductive layer can also be improved, and a joining interface can be stabilized more.
  • the thickness of the bonding metal layer formed at the time of manufacturing the heat dissipation substrate is preferably in the range of 0.003 to 10 ⁇ m. This is because if the bonding metal layer is thinner than 0.003 ⁇ m, the effect of bonding the first metal and the second metal (and the first metal and the third metal) may not be sufficiently obtained, and conversely, it is thicker than 10 ⁇ m. This is because the thermal conductivity and electrical conductivity of the heat dissipation substrate may be reduced by the bonding metal layer.
  • the above-mentioned thickness of the bonding metal layer is a thickness formed at the time of manufacturing the heat dissipation substrate, and in the heating and pressurizing steps described later, a part of the bonding metal layer is formed from the via as a bonding surplus together with an excessive amount of the insert made of the second metal. Extruded. Further, even if the bonding metal layer is formed with a uniform thickness when manufacturing the heat dissipation substrate, a part of the bonding metal layer is formed at the interface between the first metal and the second metal (and the first metal and the third metal) in the heating and pressurizing steps. Sometimes it moves. Therefore, in the heat dissipation board after manufacture, the bonding alloy layer is not always formed continuously at the interface between the first metal and the second metal (and the interface between the first metal and the third metal). In some cases, the bonding alloy layer may intermittently exist.
  • the melting point of Cu is 1083 ° C.
  • Cu (second metal, third metal) and a part of Ni (fourth metal) may form a solid solution even at temperatures lower than 1083 ° C. . Even if such a solid solution is formed at a part of the interface with the first metal, there is no fear that the thermal conductivity is significantly reduced unless the layer of the solid solution is excessively thick. However, it is preferable that no solid solution exists at the bonding interface between the first metal, the second metal, and the third metal. From this viewpoint, the heating temperature during bonding is desirably 1000 ° C. or lower.
  • the first metal is Mo and the second metal (and the third metal) is Cu
  • a Ni layer having a thickness of 3 ⁇ m can be suitably used as the bonding alloy layer.
  • the heat dissipation substrate can be manufactured without increasing the bondability between Cu and Mo and without affecting the thermal conductivity and electrical conductivity.
  • Ni and Ni alloys have also been widely used for Ni-based plating for soldering semiconductor devices to heat dissipation substrates, and it is known that no blistering or peeling occurs even when heated to 400 ° C. ing. Therefore, when the Ni layer (or Ni alloy layer) is used as the bonding metal layer, there is no fear of causing a problem in the heat cycle test.
  • pure Ni is soft and has a linear expansion coefficient of 8.3ppm / k (intermediate value between the linear expansion coefficient of Cu and that of Mo). The effect of suppressing is also acquired.
  • soft Ni on the bonding surface of Cu and Mo, even if cracks or peeling occurs at the interface between Cu and Mo, the rapid progress can be suppressed.
  • Cu which is a third metal, each of which is made of Cu, which is a second metal, on one side of a plate-like member that is 100 mm square and 0.51 mm thick and has a diameter slightly smaller than the diameter of the via.
  • Two plate-like members provided with cylindrical convex portions of 0.27 mm are prepared.
  • a guide is placed on the outer periphery of the plate-shaped member made of the third metal, the position of the via of the core base material made of the first metal is matched with the position of the convex portion, and the via is inserted into each convex portion. Then, the convex part formed in the single side
  • a guide having the same thickness (here, 0.5 mm) as the heat conductive layer of the heat dissipation board after manufacture is used.
  • the thickness of the SUS guide plate used in the above example is appropriately changed. It can be adjusted by doing.
  • the guide is effective in controlling the thickness of the internal Cu layer (Cu layers other than the front and back surfaces of the heat dissipation board). is there.
  • the insert when manufacturing a heat dissipation substrate with a multilayer clad structure, by providing protrusions on the front and back surfaces of the Cu plate-like member, the insert can be inserted from the protrusions in the same manner as the heat dissipation substrate with the three-layer clad structure described above. Can be produced.
  • heating and pressing device hot press (HP) device, current sintering device, hot isostatic pressing (HIP) device, heating and pressing furnace, etc.
  • heating and pressurizing are performed in a non-oxidizing atmosphere (for example, a reducing gas atmosphere, an inert gas atmosphere such as Ar, N 2 , or a vacuum atmosphere, which may be a combination of a reducing gas and an inert gas).
  • a non-oxidizing atmosphere for example, a reducing gas atmosphere, an inert gas atmosphere such as Ar, N 2 , or a vacuum atmosphere, which may be a combination of a reducing gas and an inert gas.
  • the heating and pressurizing conditions vary depending on the size of the heat dissipation board and the type of each metal used.
  • a pressure in the range of 30 MPa (0.3 tf / cm 2 ) to 500 MPa (5 tf / cm 2 ) is applied, and from 600 ° C Heating to a temperature below the melting point of Cu (1083 ° C or lower) is sufficient. From the viewpoint of softening and not melting Cu, the heating temperature is preferably in the range of 600 ° C to 1000 ° C.
  • the laminated body of the present example has a thickness after heating and pressurization of about 1.5 mm, and Cu and Mo inserted into the via are joined via an insert metal (Ni). As conditions for producing the laminated body, it is preferable that a bonding surplus comes out from the bonding interface between the Cu layer and the via Mo layer after bonding.
  • various heating and pressurizing apparatuses can be used. However, like a spark plasma sintering (SPS) device, do not use a heating and pressurizing device that may melt local Cu and form voids at the interface with Mo, or will not cause local melting Limited to conditions.
  • SPS spark plasma sintering
  • the minimum value of the above temperature range is higher than the heating temperature in the conventional solid phase diffusion bonding, the Cu inserts inserted into the vias, and the Cu plate-like members arranged on the front and back surfaces of the core base material are softened, and the inside of the vias It is for press-fitting into.
  • the minimum value of the above pressure range is higher than the pressure in the conventional solid phase diffusion bonding, similarly, Cu inserts inserted into vias, and Cu plate-like members arranged on the front and back surfaces of the core substrate This is to soften and press fit into the via.
  • the bonding strength at the interface between Cu and Mo inside the via may not be stable. There is no problem even if the pressure is higher than the above range, but it is necessary to use a large apparatus to increase the pressure, which increases the manufacturing cost.
  • the laminated body When the laminated body is heated and pressurized, joining between Cu and Cu and Mo is started. In parallel with this, the softened Cu is plastically deformed and the voids at the interface disappear. However, if the amount of Cu introduced into the via is small when the stacked body is manufactured, the bonding is completed with the gap remaining at the interface. In this case, since the pressure applied in the via is low and unstable, there is a possibility that sufficient bonding strength cannot be obtained. In the above manufacturing method, the amount of Cu to be pressed into the via from the Cu insert or the Cu insert and the Cu plate member is made larger than the volume of the via, that is, an excessive amount of Cu is introduced into the via.
  • a stable heat dissipation substrate can be formed with high bonding strength even inside the via.
  • the thickness of Cu can be appropriately controlled by using a guide material.
  • the guide material in addition to the above-mentioned SUS, those made of Mo, W, In, Kv whose thickness does not easily change even when heated and pressurized like SUS can be suitably used.
  • Cu and Mo bondability is enhanced by introducing Ni, which is an insert metal, into the Cu-Mo interface in a CuMo-based hybrid structure heat dissipation substrate. Moreover, by softening Cu and press-fitting it in a solid state, the insert metal does not dissolve in Cu and the thermal conductivity does not decrease.
  • a highly reliable heat dissipation board that suppresses the decrease in thermal conductivity after the heat cycle test by press-fitting the amount of Cu that generates excess bonding (that is, press-fitting Cu that exceeds the volume of the via). Obtainable. By generating a bonding surplus, it is possible to confirm that the amount of Cu that is greater than the volume of the via has been press-fitted, that is, a state in which there is no void in the via is formed. Excess or deficiency of the amount of Cu introduced into can be easily determined from the appearance.
  • the joining process of the heat dissipation board has not been managed by the appearance of surplus joining, but for example, when manufacturing a large thin heat dissipating board for cutting out a large number of heat dissipating boards, the joining surplus By providing a window for confirming the above, the overall joining quality can be managed.
  • the above manufacturing method can also be used for manufacturing a heat dissipation substrate having a multilayer hybrid structure (Cu / via Mo / Cu / via Mo /... / Cu) having 5 to 11 layers, for example.
  • a Cu plate member and an appropriate number of Mo plate members (core base material) filled with a Cu insert inside the via are alternately arranged to form a carbon jig.
  • the core base material can be made thinner (that is, the via is shallower) as the number of stacked layers is increased, so that Cu can be easily pressed into the via. Since the thickness of Mo or the like described above is difficult to change, the thickness of the front and back surfaces of the heat dissipation substrate and the intermediate Cu layer can be controlled by using a guide made of Mo or the like. If the tolerance of the Cu layer thickness of the heat dissipation board to be manufactured is large (allowable error range is wide) and there is a margin, the guide does not necessarily have to be used.
  • the linear expansion coefficient of the heat dissipation board is an important characteristic that affects the manufacturing and performance of the semiconductor module, and there is an optimum value for each performance and structure according to the purpose of the semiconductor module.
  • the Cu layer has been thickened to increase the thermal conductivity, but when the Cu layer becomes thicker, the thermal expansion at the extreme surface layer of the Cu surface layer is suppressed by the Mo layer or CuMo layer.
  • the Cu surface layer that is, the surface layer of the heat dissipation substrate
  • the linear expansion coefficient in the temperature range from room temperature (RT) to 800 ° C is evaluated.
  • the linear expansion coefficient at 800 ° C is required to be 10 ppm / K or less when manufacturing semiconductor packages.
  • the ceramic substrate is brazed to the heat dissipation substrate, and the process of brazing the ceramic substrate to the heat dissipation substrate is not performed, it is not always necessary to satisfy the characteristic that the linear expansion coefficient is low at a high temperature of 800 ° C.
  • a process of soldering a semiconductor device to a heat dissipation substrate is included in the manufacture of a semiconductor package, it is required to have a low linear expansion coefficient (for example, 10 ppm / K or less) at 400 ° C. at which the process is performed.
  • the upper limit of the temperature range may be set to 800 ° C. or 400 ° C. depending on the assumed process.
  • it is an indispensable requirement to have an appropriate linear expansion coefficient that is, a linear expansion coefficient comparable to each member to which the heat dissipation board is attached) at the operating temperature of the semiconductor device.
  • the measurement of the linear expansion coefficient was performed by cutting out a test piece having a length of 20 mm, a width of 10 mm, and a thickness of 1.5 mm using a wire electric discharge machining (WEDM) device from a heat dissipation substrate manufactured under each condition described later.
  • WEDM wire electric discharge machining
  • the cut specimen was only removed of the joining surplus, not chamfered, and RT ⁇ was measured using a linear expansion coefficient measuring device (manufactured by Seiko Instruments Inc.).
  • the linear expansion coefficient was measured in the temperature range of 800 ° C., and the maximum value was obtained.
  • the linear expansion coefficient of one direction (X direction) parallel to the surface and the direction (Y direction) orthogonal to this one direction was measured, and those maximum values were subjected to evaluation. .
  • the heat dissipation substrate cools the heat generated during the operation of the semiconductor device, and naturally has a high thermal conductivity. If the thermal conductivity is low, the semiconductor device cannot be cooled, and there is a risk that the semiconductor module will be damaged or burnt out.
  • a standard of thermal conductivity for example, 400 W / m ⁇ K, which is the value of thermal conductivity of Cu, or 200 W / m ⁇ K, which is a half value thereof, is used.
  • the heat dissipation board plays a role of releasing the heat of the semiconductor device attached to one surface to the cooler attached to the surface opposite to the surface, so that heat conduction in the thickness direction (Z-axis direction) is particularly important. A high rate is required.
  • a test piece having a diameter of 20 mm and a thickness of 1.5 mm was cut out from the heat dissipation substrate of each example, and the heat conductivity in the Z-axis direction was measured at room temperature using a thermal conductivity measurement device (FTC-RT, manufactured by Advance Riko Co., Ltd.) The rate was measured 3 times.
  • FTC-RT thermal conductivity measurement device
  • the heat dissipation substrate of each example was used as it was, and the thermal conductivity in the X-Y plane was measured three times using a laser flash method thermal conductivity measuring device (TC-7000 manufactured by Advance Riko Co., Ltd.).
  • the minimum value before the heat cycle test is 200 W / m ⁇ K or more in the Z-axis direction, 200 W / m ⁇ K or more in the XY plane, and the minimum thermal conductivity in the Z-axis direction after the heat cycle test.
  • the evaluation standard was that the value was 200 W / m ⁇ K or less.
  • High electrical conductivity is also required for the heat dissipation substrate to function as an electrode.
  • an Al alloy having a thermal conductivity of 50% IACS or more is used instead of an Al lead wire. It has come to be.
  • the heat dissipation substrate electrode is also required to have an electric conductivity of 50% IACS.
  • W or Mo as a heating element in the main electric path
  • the energization may become unstable. Therefore, when the heat radiating substrate also functions as an electrode, it is preferable that W or Mo does not exist in the energization path.
  • Mo is used as the core base material.
  • the main energization path is Cu existing inside the via of the core base material, there is no concern that the energization becomes unstable.
  • the electrical conductivity is measured by a four-terminal method of measuring electrical conductivity using a four-terminal method (Cut ) Measured by using Napson RT70V).
  • the electrical resistance value at RT is measured three times, and the minimum value of the measurement result is higher than the electrical conductivity (50% IACS) of the Al alloy that is the lead material used in semiconductor devices.
  • As a general method for measuring electrical conductivity a method for measuring eddy current with a sigma tester is also known, but a method for measuring a case where the inside is a plurality of different structures like the heat dissipation substrate of this embodiment. The four terminal method was used this time.
  • Ni plating property evaluation CuW and CuMo heat sinks themselves have poor brazing and soldering characteristics, making it difficult to perform good nickel plating. If there is a problem with the Ni plating process, it will not be possible to perform a mounting operation test after the heat dissipation board is peeled off from various members and semiconductor devices in a heat cycle test of a semiconductor package or semiconductor module. On the other hand, such a problem does not occur in the heat dissipation substrate of the CuMo-based hybrid structure as in the present embodiment because the surface layer is Cu and a good Ni-based plating treatment can be performed.
  • the Ni-based plating treatment was evaluated based on the fact that no swelling occurred on the surface after leaving at 400 ° C. for a predetermined time.
  • a test piece was cut out from the heat dissipation board manufactured by the above method by punching or cutting with a press machine, and the surface of the heat dissipation board in each example was subjected to Ni-based plating treatment.
  • Ni plating of the heat dissipation board there are various methods for Ni plating of the heat dissipation board based on the manufacturing know-how of semiconductor module manufacturers and semiconductor package manufacturers.
  • the surface layer of the heat dissipation substrate of the clad structure or hybrid structure is Cu, and a simple Ni plating process is possible.
  • Ni-based plating process there are a technique of plating Ni-P and Ni-B and a technique of heat treatment thereon.
  • Au plating may be applied.
  • the heat dissipation substrate is thin, it is difficult to measure the bonding strength of the laminated interface of the heat dissipation substrate having a hybrid structure or a clad structure. In particular, it is difficult to measure the bonding strength of the laminated interface of the heat dissipation substrate having a hybrid structure.
  • a general method for measuring tensile strength there is a possibility that the joint between Cu and Mo may be damaged when a measuring jig (shank) is attached. Also, the measurement of the bending strength was abandoned because it was difficult to produce a test piece.
  • semiconductor packages are manufactured for various purposes, and their configurations are also diverse.
  • a 20 mm square, 1.5 mm thick heat dissipation board is Ni-plated with a thickness of 5 ⁇ m, and this has an outer diameter of 20 mm square, an inner diameter of 15 mm square,
  • a frame-shaped member made of ceramic having a thickness of 0.5 mm and a member such as a metal terminal were attached by Ag brazing (Ag melting point is 780 ° C., brazed at 800 ° C.).
  • the fabricated semiconductor package is heated to 250 ° C and held for 5 minutes, then cooled to -40 ° C and held for 5 minutes. After repeating the cycle for 100 cycles, it was visually confirmed that there was no problem in the semiconductor package.
  • Some semiconductor packages include those in which various members are soldered to a heat dissipation board, and those in which a frame-like member made of resin or the like is attached with an insert or an adhesive.
  • Plastic packages and metal packages are also known, but the heat cycle test of ceramic packages is the strictest, and there is knowledge that other types of semiconductor packages will not cause problems if the heat dissipation board passes this .
  • the heat sink of the semiconductor package is Au plated, and a 10mm square, 1.0mm thick GaN chip is attached with AuSi solder (melting point 380 ° C, soldered at 400 ° C), and lead wires are attached, and then the lid A semiconductor module was manufactured.
  • the fabricated semiconductor module is heated to 250 ° C and held for 5 minutes, then it is cooled to -40 ° C and held for 5 minutes.
  • the heating and cooling cycle is repeated 100 times, and the lid is removed after the heat cycle test, causing problems with the semiconductor module. It was visually confirmed whether or not the above occurred.
  • the heat dissipation board of the semiconductor package is Au plated, and further 10mm square with AuSi solder (melting point 380 ° C, soldered at 400 ° C)
  • AuSi solder melting point 380 ° C, soldered at 400 ° C
  • a GaN chip as a dummy heating element having a thickness of 1.0 mm was attached, lead wires were attached, and a lid was put on to produce a semiconductor module.
  • a cooler was further attached.
  • the GaN chip is energized, heated to 250 ° C and held for 5 minutes, then cooled to -40 ° C and held for 5 minutes.
  • the heating / cooling cycle was repeated 100 cycles.
  • the lid was removed.
  • the module was checked visually for problems. Also, if thermal damage occurred on the way, it was stopped.
  • heat cycle test of the heat dissipation substrate alone, the semiconductor package, and the semiconductor module described above is a destructive test, and another test piece (heat dissipation substrate) was used for each test.
  • These heat cycle tests were performed in the order of the heat dissipation substrate alone, the semiconductor package, and the semiconductor module, and the test piece (heat dissipation substrate) to be used in the next test was determined based on the result of the previous heat cycle test.
  • a heat cycle test was performed using 5 heat sink substrates alone cut out at different positions on a large (100mm square) heat sink board, and the vicinity of the heat sink board with the lowest characteristics (low thermal conductivity)
  • the heat dissipation substrate cut out at the position was used for the heat cycle test of the semiconductor package to be performed next.
  • the test piece (heat dissipating substrate) to be used was determined in the same manner as described above, based on the results of the three types of heat cycle tests performed previously. By performing the test under such severe conditions, the reliability of the heat dissipation board that has passed the test and the semiconductor package or semiconductor module on which the heat dissipation board is mounted is ensured.
  • a large number of large heat dissipation boards are prepared, and a test piece (heat dissipation board) cut out from another large heat dissipation board at the same location as the heat dissipation board cut-out position that has the lowest characteristics in the heat cycle test of the heat dissipation board alone. ) May be used for the heat cycle test of the semiconductor package, the heat cycle test of the semiconductor module, and the operation life test.
  • Examples 1 and 2 are heat dissipation substrates with a three-layer hybrid structure (Fig. 1 (c)), and Example 3 is a heat dissipation substrate with a five-layer hybrid structure (Fig. 1 (d)).
  • the linear expansion coefficient and the thermal conductivity were measured.
  • Cu inserts and Cu plate-like members are used in such amounts that bonding surpluses are generated on any of the four sides of the outer periphery of the heat dissipation substrate after the heating and pressurizing treatment (in the table below, “all In Example 3, Cu inserts and Cu plate-like members were used in such an amount that bonding surplus was generated only in a part of the outer periphery of the heat dissipation substrate (described as “part” in the table below).
  • a laminate of hybrid structures was prepared.
  • 0.5mm thick plate-shaped member made of the first metal (Mo) in the 100mm square area at the center, 3 pieces of 5mm square unit area each with a diameter of 2.06mm (radius 1.03mm) A through hole was formed. That is, a total of 1,200 through holes were formed in a 100 mm square region at the center of the plate-like member. In the 100 mm square region, the ratio of the through holes in the cross section of the plate-like member is about 40%.
  • the inner wall surface of the via and the front and back surfaces of the plate-like member were plated with a fourth metal (Ni) as an insert metal to a thickness of 3 ⁇ m.
  • a fourth metal Ni
  • two guides which are plate members made of SUS and having a thickness of 0.5 mm, each having an outer diameter of 110 mm square and a hole of 103 mm square formed therein were prepared.
  • the second metal (Cu) is slightly smaller than the outer diameter of the via ( ⁇ 2.06mm) on one side of two plate-like members made of the third metal (Cu), 100mm square and 0.53mm thick. Convex parts having a diameter of 2.0 mm and a height of 0.27 mm were formed by etching.
  • a Cu plate-like member is placed with the surface on which the convex portion is formed facing upward, and a guide is placed on the outer periphery thereof.
  • veer currently formed in the core base material of Mo is inserted from the upper part of each convex part.
  • a protrusion formed on one surface of another Cu plate member is inserted into the via formed in the Mo core substrate, and a laminate is created by placing a guide on the outer periphery thereof.
  • the lower punch of the carbon jig was raised to the top, the laminated body was set thereon, the lower punch was lowered, and the upper punch was inserted.
  • the carbon jig to which the laminate was fixed was set in an HP heating and pressurizing apparatus, and a pressure of 100 MPa (about 1.0 tf / cm 2 ) was applied in a vacuum atmosphere and heated to 900 ° C. Thereafter, the temperature was maintained for 30 minutes, and when it was gradually cooled to 100 ° C. or lower, it was taken out. The outer periphery of the heat dissipation board was confirmed to check the state of the joining surplus.
  • the thickness was larger than the designed value of 1.5 mm, the thickness was adjusted to 1.5 mm by polishing. Thereafter, the sample was cut into a predetermined size by WEDM and used as a measurement sample.
  • Five heat radiating substrates of Examples 1 to 3 were prepared and evaluated as follows.
  • the degree of decrease in bonding strength can be seen from the change (degree of decrease) in thermal conductivity before and after the heat cycle test of the heat dissipation board alone.
  • the decrease in thermal conductivity before and after the heat cycle is small, and the Cu-Mo interface in the laminated structure and the Cu-Mo interface inside the via are firmly bonded. I understand.
  • the surplus quantity is small.
  • the decrease in thermal conductivity before and after the heat cycle test was somewhat suppressed.
  • the above-described embodiment is an example, and can be appropriately changed in accordance with the gist of the present invention.
  • Cu / via CuMo / Cu / via CuMo /... / Cu can also be used for a heat dissipation substrate having a multilayer clad structure.
  • heat dissipation substrates other than the above-described embodiments can also be used as heat dissipation substrate electrodes if the heat dissipation substrate alone satisfies the above requirements and has an electrical conductivity of 50% IACS.
  • the above method of interposing Ni with good wettability against Mo and Cu as an insert metal at the interface between Mo and Cu not only increases the bonding strength of Cu and Mo inside the via, but also on the via Mo layer and its front and back surfaces. It is also effective in increasing the bonding strength of the Cu layer located. That is, the present invention is effective not only for the heat dissipation substrate having a hybrid structure but also for a heat dissipation substrate having a clad structure. Furthermore, the heat dissipation board
  • the surface layer portion can be a hybrid structure and the inside can be a clad structure, or conversely, the surface layer portion clad structure can be a hybrid structure.
  • the heat dissipation of this embodiment has a high thermal conductivity in the Z-axis direction. Even if the substrate is attached to one surface of the semiconductor device and cooled, the substrate may not be cooled to the heat resistant temperature of the edge resin sheet.
  • the electrode configuration is shifting from the horizontal electrode type to the vertical electrode type, but the conventional heat dissipation electrode of CuW or Mo has a problem that the thermal conductivity and electric conductivity are insufficient, and the performance is improved. could not cope with.
  • the heat dissipation substrate of this embodiment having a large thermal conductivity and electrical conductivity, it is possible to cope with higher performance of the LED and to reduce the cost.
  • the semiconductor module provided with the above heat dissipation substrate is various, such as memory, IC, LSI, communication, power semiconductor, sensor, LED, and it is assumed that it will further expand in the future.
  • the semiconductor device can be efficiently cooled by using the heat dissipation substrate electrode bonded to the top or bottom or one side of the semiconductor device, and the energization cross-sectional area should be increased to ensure a large energization capacity. Can do.
  • a heat dissipation substrate electrode having a structure for cooling both sides of an insulated gate bipolar transistor (IGBT) semiconductor device.
  • IGBT insulated gate bipolar transistor

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Abstract

Un substrat de dissipation de chaleur comprend : un matériau de base central en forme de plaque comprenant du Mo, dans lequel est formé un trou traversant qui traverse dans le sens de l'épaisseur ; un corps d'insertion remplissant l'intérieur du trou traversant et comprenant du Cu et n'ayant pas de vides ; une première couche de jonction formée de façon continue ou discontinue entre la surface de paroi interne du trou traversant et le corps d'insertion, la première couche de liaison comprenant du Ni et n'ayant pas de vides ; une couche thermoconductrice formée sur les surfaces avant et arrière du matériau de base central, la couche thermoconductrice comprenant uniquement du Cu et n'ayant pas de vides ; et une seconde couche de jonction formée de façon continue ou discontinue sur la surface d'interface entre le matériau de base central et la couche thermoconductrice, la seconde couche de jonction comprenant du Ni et n'ayant pas de vides. La valeur maximale du coefficient de dilatation linéaire du substrat de dissipation de chaleur dans la plage de température allant de la température ambiante à 800 °C est inférieure ou égale à 10 ppm/K, la conductivité thermique dans la direction perpendiculaire à la surface à température ambiante est supérieure ou égale à 200 W/m∙K, et la conductivité thermique dans la direction perpendiculaire à la surface est supérieure ou égale à 200 W/m∙K après réalisation d'un test de cycle thermique dans lequel le chauffage à 250 °C et le refroidissement à -40 °C sont répétés 100 fois.
PCT/JP2018/008075 2017-04-14 2018-03-02 Substrat de dissipation de chaleur, électrode de substrat de dissipation de chaleur, boîtier de semi-conducteur et module semi-conducteur WO2018190023A1 (fr)

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JP7126200B2 (ja) * 2018-09-28 2022-08-26 株式会社カネカ 半導体関連部材の熱拡散性能の評価方法および評価装置並びに半導体関連部材の熱抵抗算出方法および算出装置
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