JP2019087716A - Semiconductor device - Google Patents

Abstract

To provide a technology capable of improving heat dissipation.SOLUTION: A first inner heat conductor 51 includes a plurality of first graphite layers 511. A second inner heat conductor 52 includes a plurality of second graphite layers 521. The plurality of first graphite layers 511 are stacked in a first direction which is a direction orthogonal to a direction in which the semiconductor element 2 and a first heat dissipation body 5 are arranged side by side. The plurality of second graphite layers 521 are stacked in a direction in which the semiconductor element 2 and the first heat dissipation body 5 are arranged side by side, or a second direction perpendicular to the direction and orthogonal to the first direction.SELECTED DRAWING: Figure 2

Description

  The technology disclosed herein relates to a semiconductor device.

  The semiconductor device disclosed in Patent Document 1 includes a semiconductor element and a heat sink joined to the surface of the semiconductor element. The heat dissipating body includes a metal heat conductor bonded to the surface of the semiconductor element. Further, the heat dissipating body is a first heat conducting body joined to the metal heat conducting body, and a second heat conducting body stacked on the first heat conducting body in the direction in which the semiconductor element and the heat dissipating body are aligned. Is equipped. The first heat conductor comprises a plurality of first graphite layers. The plurality of first graphite layers are stacked in a first direction which is a direction orthogonal to the direction in which the semiconductor element and the heat sink are arranged. The second heat conductor comprises a plurality of second graphite layers. The plurality of second graphite layers are stacked in a first direction which is a direction orthogonal to the direction in which the semiconductor element and the heat sink are arranged. The plurality of first graphite layers and the plurality of second graphite layers are stacked in the same first direction. In the semiconductor device of Patent Document 1, it is necessary to make the stacking direction of the plurality of first graphite layers coincide with the stacking direction of the plurality of second graphite layers in order to obtain a flexible thermal conduction structure.

  In the semiconductor device of Patent Document 1, when the semiconductor element operates, heat is generated in the semiconductor element. The heat generated in the semiconductor element is dissipated by the heat sink. Heat is conducted by the metal heat conductor of the heat sink, the first heat conductor, and the second heat conductor, and the heat is dissipated. The heat generated in the semiconductor element is first conducted by the metallic thermal conductor joined to the semiconductor element, and then conducted by the first thermal conductor joined to the metallic thermal conductor, and then the first thermal conduction. Conducted by a second heat conductor laminated to the body.

  The thermal conductivity of the first graphite layer has anisotropy. The first graphite layer conducts less heat in the direction in which the plurality of first graphite layers are stacked. On the other hand, the first graphite layer conducts heat with high thermal conductivity in the direction orthogonal to the direction in which the plurality of first graphite layers are stacked. Therefore, in the first thermal conductor, heat is conducted with high thermal conductivity in the direction in which the semiconductor element and the heat sink are aligned (the direction orthogonal to the direction in which the plurality of first graphite layers are stacked). In the first thermal conductor, a second direction (a direction in which a plurality of first graphite layers are stacked) which is a direction perpendicular to the direction in which the semiconductor element and the heat sink are aligned and orthogonal to the first direction. Heat is conducted with high thermal conductivity in the orthogonal direction).

  Similarly, the thermal conductivity of the second graphite layer is anisotropic. The second graphite layer does not conduct much heat in the direction in which the plurality of second graphite layers are stacked. On the other hand, the second graphite layer conducts heat with high thermal conductivity in the direction orthogonal to the direction in which the plurality of second graphite layers are stacked. Therefore, in the second thermal conductor, heat is conducted with high thermal conductivity in the direction in which the semiconductor element and the heat sink are aligned (the direction orthogonal to the direction in which the plurality of second graphite layers are stacked). Further, in the second heat conductor, a second direction (a direction in which a plurality of second graphite layers are stacked) which is a direction perpendicular to the direction in which the semiconductor element and the heat sink are aligned and orthogonal to the first direction. Heat is conducted with high thermal conductivity in the orthogonal direction).

Unexamined-Japanese-Patent No. 2017-112334

  In the semiconductor device of Patent Document 1, the first thermal conductor and the second thermal conductor conduct heat with high thermal conductivity in the direction in which the semiconductor element and the heat sink are aligned. In addition, the first heat conductor and the second heat conductor have a heat conductivity high in a second direction perpendicular to the direction in which the semiconductor element and the heat sink are aligned and orthogonal to the first direction. Conduct The first thermal conductor and the second thermal conductor do not conduct much heat in the first direction (the direction in which the plurality of first graphite layers and the plurality of second graphite layers are stacked). Therefore, the heat generated in the semiconductor element can not be dissipated much in the first direction, and there is a problem that the heat dissipation is low. Thus, the present specification provides a technique that can improve the heat dissipation.

  A semiconductor device disclosed in the present specification includes a semiconductor element and a first heat dissipation body joined to a first surface of the semiconductor element. The first heat radiator is a first outer heat conductor of metal joined to the first surface of the semiconductor element, and a first inner heat conductor disposed inside the first outer heat conductor. And a second inner heat conductor disposed inside the first outer heat conductor and stacked on the first inner heat conductor in the direction in which the semiconductor element and the first heat radiator are aligned. It is equipped with the body. The first inner heat conductor comprises a plurality of first graphite layers. The second inner heat conductor comprises a plurality of second graphite layers. The plurality of first graphite layers are stacked in a first direction which is a direction orthogonal to the direction in which the semiconductor element and the first heat dissipation body are arranged. The plurality of second graphite layers are stacked in a direction in which the semiconductor element and the first heat dissipating member are aligned, or in a second direction orthogonal to the direction and orthogonal to the first direction. There is.

  According to this configuration, when the semiconductor element operates, heat is generated in the semiconductor element. The heat generated by the semiconductor element is dissipated by the first radiator. Heat is conducted and dissipated by the first outer heat conductor, the first inner heat conductor, and the second inner heat conductor of the first heat radiator. The heat generated in the semiconductor element is first conducted by the first outer thermal conductor of the metal joined to the semiconductor element, and subsequently with the first inner thermal conductor disposed inside the first outer thermal conductor It is conducted by the second inner heat conductor, conducted again by the first outer heat conductor, and dissipated to the outside.

  The first inner heat conductor comprises a plurality of first graphite layers, and the second inner heat conductor comprises a plurality of second graphite layers. The thermal conductivity of graphite is higher than the thermal conductivity of metals. Therefore, in the first heat radiator, by providing the plurality of first graphite layers and the plurality of second graphite layers, heat can be conducted more efficiently than in the case of using only metal.

  The thermal conductivity of each first graphite layer has anisotropy due to the relationship of carbon atom bonding of graphite. The first graphite layer conducts less heat in the direction in which the plurality of first graphite layers are stacked. On the other hand, the first graphite layer conducts heat with high thermal conductivity in the direction orthogonal to the direction in which the plurality of first graphite layers are stacked. The plurality of first graphite layers are stacked in a first direction which is a direction orthogonal to the direction in which the semiconductor element and the first heat dissipation body are arranged. Therefore, in the first inner heat conductor, the heat is conducted with high thermal conductivity in the direction in which the semiconductor element and the first heat sink are aligned (the direction orthogonal to the direction in which the plurality of first graphite layers are stacked) Be done. Further, in the first inner heat conductor, heat is conducted with high thermal conductivity in a second direction (direction orthogonal to the direction in which the plurality of first graphite layers are stacked) orthogonal to the first direction.

  Similarly, the thermal conductivity of each second graphite layer has anisotropy due to the relationship of the carbon atoms of graphite. The second graphite layer does not conduct much heat in the direction in which the plurality of second graphite layers are stacked. On the other hand, the second graphite layer conducts heat with high thermal conductivity in the direction orthogonal to the direction in which the plurality of second graphite layers are stacked. In one aspect, the plurality of second graphite layers are stacked in the direction in which the semiconductor element and the first heat dissipation body are aligned. Therefore, in the second inner heat conductor, a first direction and a second direction (a plurality of second graphite layers are stacked in a direction perpendicular to the direction in which the semiconductor element and the first heat sink are aligned) Heat is conducted with high thermal conductivity in the direction perpendicular to the direction). Alternatively, in another aspect, the plurality of second graphite layers are stacked in a second direction orthogonal to the direction in which the semiconductor element and the first heat dissipation body are aligned, and orthogonal to the first direction. Therefore, with this second inner heat conductor, heat is transmitted with high thermal conductivity in the direction in which the semiconductor element and the first heat sink are aligned (the direction orthogonal to the direction in which the plurality of second graphite layers are stacked) Conducted. Further, in the second inner heat conductor, heat is conducted with high thermal conductivity in a first direction (direction orthogonal to the direction in which the plurality of second graphite layers are stacked) orthogonal to the second direction.

  According to the above configuration, the heat generated in the semiconductor element can be conducted to the first inner heat conductor and the second inner heat conductor by the metal first outer heat conductor. Moreover, the heat conductivity is high in the direction in which the semiconductor element and the first radiator are aligned, in the first direction, and in the second direction by the first inner heat conductor and the second inner heat conductor. Can be conducted. Also, the heat conducted by the first inner heat conductor and the second inner heat conductor can be dissipated in multiple directions by the first outer heat conductor. Therefore, according to the above configuration, the heat generated in the semiconductor element is efficiently conducted by the first outer heat conductor, the first inner heat conductor, and the second inner heat conductor of the first heat radiator, and the multi-directional Since the heat can be dissipated, the heat dissipation can be improved.

FIG. 1 is a cross-sectional view of a semiconductor device according to a first embodiment. It is an enlarged view of principal part II of FIG. It is a perspective view of each graphite layer concerning a 1st example. It is an enlarged view of principal part IV of FIG. It is sectional drawing of the semiconductor device concerning 2nd Example. FIG. 18 is a cross-sectional view of a semiconductor device in a modification of the second embodiment. It is a figure corresponding to FIG. 2 of the semiconductor device which concerns on another Example. It is a figure which shows the measurement result of a 1st test example. It is a figure which shows the measurement result of the 2nd test example.

(First embodiment)
A semiconductor device 1 according to an embodiment will be described with reference to the drawings. As shown in FIG. 1, the semiconductor device 1 according to the embodiment includes a semiconductor element 2, a first heat radiating body 5, a second heat radiating body 7, and a conductive plate 3. The semiconductor element 2, the first heat radiating body 5, the second heat radiating body 7, and the conductive plate 3 are arranged in the Z direction. The semiconductor element 2, the first heat radiating body 5, the second heat radiating body 7, and the conductive plate 3 are sealed by a sealing resin 90. An epoxy resin can be used as a material of the sealing resin 90. In addition, the sealing resin 90 may contain a curing agent, a stress relaxation agent, a curing accelerator, a filler, and the like. The semiconductor device 1 shown in FIG. 1 may be called a power card.

  The semiconductor element 2 is formed of, for example, a substrate such as silicon (Si) or silicon carbide (SiC). In the semiconductor element 2, an element structure such as, for example, an insulated gate bipolar transistor (IGBT) or a metal oxide semiconductor field effect transistor (MOSFET) is formed. When the element structure is, for example, an IGBT, an emitter region, a collector region, a body region, a drift region, a gate electrode and the like are formed in the semiconductor element 2 (not shown). The semiconductor element 2 generates heat when the semiconductor device 1 operates.

  A front surface electrode is disposed on the front surface 21 of the semiconductor element 2 (not shown). The surface electrode covers the surface 21 of the semiconductor element 2. The surface electrode has conductivity. The surface electrode is made of, for example, an aluminum silicon alloy (AlSi). The surface electrode is electrically connected to, for example, an emitter region formed in the semiconductor element 2.

  A back surface electrode is formed on the back surface 22 of the semiconductor element 2 (not shown). The back surface electrode covers the back surface 22 of the semiconductor element 2. The back electrode has conductivity. The back surface electrode is formed of, for example, nickel (Ni). The back surface electrode is electrically connected to, for example, a collector region formed in the semiconductor element 2.

  The first heat radiating body 5 is joined to the back surface 22 (an example of the first surface) of the semiconductor element 2. The first heat radiating body 5 is joined to the back surface 22 of the semiconductor element 2 by the solder 91. The first heat radiating body 5 is joined to the back surface electrode formed on the back surface 22 of the semiconductor element 2. The first heat radiating body 5 is electrically connected to the back surface electrode. As the solder 91, for example, Sn-based solder, SnCu-based solder, Zn-based solder or the like can be used.

  The first heat radiator 5 includes a first outer heat conductor 53, a first inner heat conductor 51, and a second inner heat conductor 52. The first outer heat conductor 53 is bonded to the back surface 22 of the semiconductor element 2. The first outer heat conductor 53 is joined to the back surface electrode formed on the back surface 22 of the semiconductor element 2 by the solder 91. The first outer heat conductor 53 is electrically connected to the back electrode.

  The first outer heat conductor 53 is made of, for example, copper (Cu). The first outer heat conductor 53 may be formed of a metal other than copper (Cu). The first outer heat conductor 53 has conductivity. The first outer heat conductor 53 is formed in a box shape. The first outer heat conductor 53 is formed in a rectangular parallelepiped shape.

  The first outer heat conductor 53 comprises an upper surface 536, a lower surface 537 and a side surface 538. The upper surface 536 of the first outer heat conductor 53 faces the semiconductor element 2 in the Z direction. The lower surface 537 faces the opposite side to the semiconductor element 2 side in the Z direction. The lower surface 537 of the first outer heat conductor 53 is in contact with the cooler 201. The cooler 201 cools the first radiator 5. The side surface 538 of the first outer heat conductor 53 is located between the upper surface 536 and the lower surface 537. The side surface 538 faces outward in the X direction and the Y direction (the side surface 538 in the Y direction is not shown).

  As shown in FIG. 2, the first outer heat conductor 53 includes a first metal body 531 and a second metal body 532. In FIG. 2, the sealing resin 90 is omitted. The first metal body 531 is bonded to the semiconductor element 2. The first metal body 531 is disposed between the semiconductor element 2 and the second metal body 532. The first metal body 531 is bonded to the surface of the second metal body 532 on the side of the semiconductor element 2. The second metal body 532 is joined to the first metal body 531. The second metal body 532 is bonded to the surface of the first metal body 531 opposite to the semiconductor element 2 side.

  The boundary 56 between the first metal body 531 and the second metal body 532 of the first outer heat conductor 53 does not exist on the upper surface 536 and the lower surface 537 of the first outer heat conductor 53. The boundary 56 between the first metal body 531 and the second metal body 532 is present on the side surface 538 of the first outer heat conductor 53.

  The first outer heat conductor 53 accommodates the first inner heat conductor 51 and the second inner heat conductor 52. The first outer heat conductor 53 surrounds the first inner heat conductor 51 and the second inner heat conductor 52. The first outer heat conductor 53 is provided with a housing space 54. The housing space 54 is formed inside the first outer heat conductor 53.

  The first inner heat conductor 51 is disposed inside the first outer heat conductor 53. The first inner heat conductor 51 is disposed in the housing space 54 of the first outer heat conductor 53. The first inner heat conductor 51 is disposed closer to the semiconductor element 2 than the second inner heat conductor 52.

  The first inner heat conductor 51 includes a plurality of first graphite layers 511. The plurality of first graphite layers 511 are stacked in a first direction (X direction) which is a direction orthogonal to the direction (Z direction) in which the semiconductor element 2 and the first heat dissipation body 5 are arranged. Each first graphite layer 511 is formed of graphite. Each first graphite layer 511 is formed by stacking a plurality of graphenes (not shown). The thermal conductivity of graphite is higher than that of metals in the high thermal conductivity direction. The thermal conductivity of copper (Cu) is about 390 W / mK. Also, the thermal conductivity of silver (Ag) is about 420 W / mK.

  The thermal conductivity of the first graphite layer 511 has anisotropy due to the relationship of bonding of carbon atoms. There is a direction in which the thermal conductivity is relatively high and a direction in which the thermal conductivity is relatively high. As shown in FIG. 3, the thermal conductivity of the first graphite layer 511 in the in-plane direction (the first high thermal conductivity direction D1 and the second high thermal conductivity direction D2) is in the out-of-plane direction (low thermal conductivity direction D3). Higher than thermal conductivity. The thermal conductivity in the first high thermal conductivity direction D1 and the second high thermal conductivity direction D2 is about 800 to 1900 W / mK. The thermal conductivity in the low thermal conductivity direction D3 is about 3 to 10 W / mK. The first high thermal conductivity direction D1, the second high thermal conductivity direction D2, and the low thermal conductivity direction D3 are orthogonal to each other. The out-of-plane direction (low thermal conductivity direction D3) of the first graphite layer 511 is the thickness direction of the first graphite layer 511.

  As shown in FIG. 2, each first graphite layer 511 is arranged such that the first high thermal conductivity direction D1 coincides with the direction (Z direction) in which the semiconductor element 2 and the first radiator 5 are aligned. It is done. Each first graphite layer 511 is disposed such that the low thermal conductivity direction D3 is orthogonal to the direction (Z direction) in which the semiconductor element 2 and the first heat dissipation body 5 are aligned. Each first graphite layer 511 conducts heat with high thermal conductivity in the Z direction. Each first graphite layer 511 does not transfer much heat in the first direction (X direction) which is the direction in which the plurality of first graphite layers 511 are stacked in the direction orthogonal to the Z direction. Each first graphite layer 511 conducts heat with high thermal conductivity in a second direction (Y direction) perpendicular to the Z direction and orthogonal to the first direction (X direction).

  The second inner heat conductor 52 is disposed inside the first outer heat conductor 53. The second inner heat conductor 52 is disposed in the housing space 54 of the first outer heat conductor 53. The second inner heat conductor 52 is disposed farther from the semiconductor element 2 than the first inner heat conductor 51.

  The second inner heat conductor 52 includes a plurality of second graphite layers 521. The plurality of second graphite layers 521 are stacked in the direction (Z direction) in which the semiconductor element 2 and the first heat dissipation body 5 are aligned. Each second graphite layer 521 is formed of graphite. Each second graphite layer 521 is formed by stacking a plurality of graphenes (not shown).

  The thermal conductivity of the second graphite layer 521 has anisotropy due to the relationship of bonding of carbon atoms. There is a direction in which the thermal conductivity is relatively high and a direction in which the thermal conductivity is relatively high. As shown in FIG. 3, the thermal conductivity of the second graphite layer 521 in the in-plane direction (the first high thermal conductivity direction D1 and the second high thermal conductivity direction D2) is in the out-of-plane direction (low thermal conductivity direction D3). Higher than thermal conductivity. The thermal conductivity in the first high thermal conductivity direction D1 and the second high thermal conductivity direction D2 is about 800 to 1900 W / mK. The thermal conductivity in the low thermal conductivity direction D3 is about 3 to 10 W / mK. The first high thermal conductivity direction D1, the second high thermal conductivity direction D2, and the low thermal conductivity direction D3 are orthogonal to each other. The out-of-plane direction (low thermal conductivity direction D3) of the second graphite layer 521 is the thickness direction of the second graphite layer 521.

  As shown in FIG. 2, each second graphite layer 521 is disposed such that the first high thermal conductivity direction D1 is orthogonal to the direction (Z direction) in which the semiconductor element 2 and the first radiator 5 are aligned. It is done. Each second graphite layer 521 is arranged such that the low thermal conductivity direction D3 coincides with the direction (Z direction) in which the semiconductor element 2 and the first radiator 5 are aligned. Each second graphite layer 521 does not transfer much heat in the Z direction. Each first graphite layer 511 conducts heat with high thermal conductivity in a first direction (X direction) and a second direction (Y direction) which are directions orthogonal to the Z direction.

  The first inner heat conductor 51 and the second inner heat conductor 52 are stacked in the Z direction. A brazing material 96 is disposed between the first outer heat conductor 53 and the first inner heat conductor 51. A brazing material 97 is disposed between the first inner heat conductor 51 and the second inner heat conductor 52. A brazing material 98 is disposed between the first outer heat conductor 53 and the second inner heat conductor 52. The first inner heat conductor 51 and the second inner heat conductor 52 are joined by a brazing material 97. The first outer heat conductor 53 and the first inner heat conductor 51 are joined by a brazing material 96. The first outer heat conductor 53 and the second inner heat conductor 52 are joined by a brazing material 98.

  As each brazing filler metal 96, 97, 98, for example, an Ag-based brazing filler metal can be used. Each brazing filler metal 96, 97, 98 contains titanium (Ti). The content ratio of titanium (Ti) of each brazing filler metal 96, 97, 98 is, for example, 5 wt% or less. The content of titanium (Ti) may be 3 to 5 wt%. In addition, the content of titanium (Ti) may be 3 wt% or less. The thickness in the Z direction of each brazing material 96, 97, 98 is, for example, 50 μm. The thickness in the Z direction may be 50 μm or less. The thickness in the Z direction may be 25 μm or less.

  As shown in FIG. 1, a conductive plate 3 is bonded to the surface 21 (an example of a second surface) of the semiconductor element 2. The front surface 21 of the semiconductor element 2 is the surface opposite to the back surface 22. The conductive plate 3 is joined to the surface 21 of the semiconductor element 2 by the solder 92. The conductive plate 3 is bonded to a surface electrode formed on the surface 21 of the semiconductor element 2.

  The conductive plate 3 is formed in a plate shape. The conductive plate 3 is made of, for example, copper (Cu). The conductive plate 3 has conductivity and thermal conductivity. The conductive plate 3 is disposed between the semiconductor element 2 and the second radiator 7, and has a function as a spacer between the two.

  The second heat radiating body 7 is joined to the conductive plate 3. The second radiator 7 is joined to the conductive plate 3 by the solder 93. The second heat radiating body 7 is joined to the surface 21 of the semiconductor element 2 through the solders 92 and 93 and the conductive plate 3. The second heat radiating body 7 is joined to the surface electrode formed on the surface 21 of the semiconductor element 2. The second radiator 7 is in electrical communication with the surface electrode. As the solders 92 and 93, for example, Sn-based solder, SnCu-based solder, Zn-based solder or the like can be used.

  The second heat sink 7 includes a second outer heat conductor 73, a third inner heat conductor 71, and a fourth inner heat conductor 72. The second outer heat conductor 73 is bonded to the surface 21 of the semiconductor element 2 through the solders 92 and 93 and the conductive plate 3. The second outer heat conductor 73 is joined to the surface electrode formed on the surface 21 of the semiconductor element 2 through the solders 92 and 93 and the conductive plate 3. The second outer heat conductor 73 is electrically connected to the surface electrode.

  The second outer heat conductor 73 is made of, for example, copper (Cu). The second outer heat conductor 73 may be formed of a metal other than copper (Cu). The second outer heat conductor 73 has conductivity. The second outer heat conductor 73 is formed in a box shape. The second outer heat conductor 73 is formed in a rectangular parallelepiped shape.

  The second outer heat conductor 73 comprises a lower surface 736, an upper surface 737 and a side surface 738. The lower surface 736 of the second outer heat conductor 73 faces the semiconductor element 2 in the Z direction. The upper surface 737 faces the opposite side to the semiconductor element 2 side in the Z direction. The upper surface 737 of the second outer heat conductor 73 is in contact with the cooler 202. The cooler 202 cools the second radiator 7. The side surface 738 of the second outer heat conductor 73 is located between the lower surface 736 and the upper surface 737. The side surface 738 faces outward in the X direction and the Y direction (the side surface 738 in the Y direction is not shown).

  As shown in FIG. 4, the second outer heat conductor 73 includes a first metal body 731 and a second metal body 732. In FIG. 4, the sealing resin 90 is omitted. The first metal body 731 is joined to the semiconductor element 2 through the solders 92 and 93 and the conductive plate 3. The first metal body 731 is disposed between the conductive plate 3 and the second metal body 732. The first metal body 731 is joined to the surface of the second metal body 732 on the side of the conductive plate 3. The second metal body 732 is joined to the first metal body 731. The second metal body 732 is joined to the surface of the first metal body 731 opposite to the conductive plate 3 side.

  The boundary 76 between the first metal body 731 and the second metal body 732 of the second outer heat conductor 73 does not exist on the lower surface 736 and the upper surface 737 of the second outer heat conductor 73. The boundary 76 between the first metal body 731 and the second metal body 732 exists on the side surface 738 of the second outer heat conductor 73.

  The second outer heat conductor 73 accommodates the third inner heat conductor 71 and the fourth inner heat conductor 72. The second outer heat conductor 73 surrounds the third inner heat conductor 71 and the fourth inner heat conductor 72. The second outer heat conductor 73 includes a housing space 74. The housing space 74 is formed inside the second outer heat conductor 73.

  The third inner heat conductor 71 is disposed inside the second outer heat conductor 73. The third inner heat conductor 71 is disposed in the housing space 74 of the second outer heat conductor 73. The third inner heat conductor 71 is disposed closer to the semiconductor element 2 than the fourth inner heat conductor 72.

  The third inner heat conductor 71 includes a plurality of third graphite layers 711. The plurality of third graphite layers 711 are stacked in a first direction (X direction) which is a direction orthogonal to the direction (Z direction) in which the semiconductor element 2 and the second heat dissipation body 7 are arranged. Each third graphite layer 711 is formed of graphite. Each third graphite layer 711 is formed by stacking a plurality of graphenes (not shown).

  The thermal conductivity of the third graphite layer 711 has anisotropy due to the relationship of bonding of carbon atoms. There is a direction in which the thermal conductivity is relatively high and a direction in which the thermal conductivity is relatively high. As shown in FIG. 3, the thermal conductivity of the third graphite layer 711 in the in-plane direction (the first high thermal conductivity direction D1 and the second high thermal conductivity direction D2) is in the out-of-plane direction (low thermal conductivity direction D3). Higher than thermal conductivity. The thermal conductivity in the first high thermal conductivity direction D1 and the second high thermal conductivity direction D2 is about 800 to 1900 W / mK. The thermal conductivity in the low thermal conductivity direction D3 is about 3 to 10 W / mK. The first high thermal conductivity direction D1, the second high thermal conductivity direction D2, and the low thermal conductivity direction D3 are orthogonal to each other. The out-of-plane direction (low thermal conductivity direction D3) of the third graphite layer 711 is the thickness direction of the third graphite layer 711.

  As shown in FIG. 4, each third graphite layer 711 is disposed such that the first high thermal conductivity direction D1 coincides with the direction (Z direction) in which the semiconductor element 2 and the second radiator 7 are aligned. It is done. Each third graphite layer 711 is disposed such that the low thermal conductivity direction D3 is orthogonal to the direction (Z direction) in which the semiconductor element 2 and the second heat dissipation body 7 are aligned. Each third graphite layer 711 conducts heat with high thermal conductivity in the Z direction. Each third graphite layer 711 does not transfer much heat in the first direction (X direction) which is the direction in which the plurality of third graphite layers 711 are stacked in the direction orthogonal to the Z direction. Each third graphite layer 711 conducts heat with high thermal conductivity in a second direction (Y direction) perpendicular to the Z direction and orthogonal to the first direction (X direction).

  The fourth inner heat conductor 72 is disposed inside the second outer heat conductor 73. The fourth inner heat conductor 72 is disposed in the housing space 74 of the second outer heat conductor 73. The fourth inner heat conductor 72 is disposed farther from the semiconductor element 2 than the third inner heat conductor 71.

  The fourth inner heat conductor 72 includes a plurality of fourth graphite layers 721. The plurality of fourth graphite layers 721 are stacked in the direction (Z direction) in which the semiconductor element 2 and the second heat dissipation body 7 are aligned. Each fourth graphite layer 721 is formed of graphite. Each fourth graphite layer 721 is formed by stacking a plurality of graphenes (not shown).

  The thermal conductivity of the fourth graphite layer 721 has anisotropy due to the relationship of bonding of carbon atoms. There is a direction in which the thermal conductivity is relatively high and a direction in which the thermal conductivity is relatively high. As shown in FIG. 3, the thermal conductivity of the fourth graphite layer 721 in the in-plane direction (the first high thermal conductivity direction D1 and the second high thermal conductivity direction D2) is in the out-of-plane direction (low thermal conductivity direction D3). Higher than thermal conductivity. The thermal conductivity in the first high thermal conductivity direction D1 and the second high thermal conductivity direction D2 is about 800 to 1900 W / mK. The thermal conductivity in the low thermal conductivity direction D3 is about 3 to 10 W / mK. The first high thermal conductivity direction D1, the second high thermal conductivity direction D2, and the low thermal conductivity direction D3 are orthogonal to each other. The out-of-plane direction (low thermal conductivity direction D3) of the fourth graphite layer 721 is the thickness direction of the fourth graphite layer 721.

  As shown in FIG. 4, each fourth graphite layer 721 is disposed such that the first high thermal conductivity direction D1 is orthogonal to the direction (Z direction) in which the semiconductor element 2 and the second radiator 7 are aligned. It is done. Each fourth graphite layer 721 is arranged such that the low thermal conductivity direction D3 coincides with the direction (Z direction) in which the semiconductor element 2 and the second heat dissipation body 7 are aligned. Each fourth graphite layer 721 does not transfer much heat in the Z direction. Each third graphite layer 711 conducts heat with high thermal conductivity in a first direction (X direction) and a second direction (Y direction) which are directions orthogonal to the Z direction.

  The third inner heat conductor 71 and the fourth inner heat conductor 72 are stacked in the Z direction. A brazing material 86 is disposed between the second outer heat conductor 73 and the third inner heat conductor 71. A brazing material 87 is disposed between the third inner heat conductor 71 and the fourth inner heat conductor 72. A brazing material 88 is disposed between the second outer heat conductor 73 and the fourth inner heat conductor 72. As the brazing material 86, 87, 88, for example, an Ag-based brazing material can be used. The third inner heat conductor 71 and the fourth inner heat conductor 72 are joined by the brazing material 87. The second outer heat conductor 73 and the third inner heat conductor 71 are joined by a brazing material 86. The second outer heat conductor 73 and the fourth inner heat conductor 72 are joined by a brazing material 88.

  The semiconductor device 1 according to the first embodiment has been described above. As is apparent from the above description, in the semiconductor device 1, the first heat dissipation body 5 is formed of the metal first outer heat conductor 53 and the first outer heat conductor 53 joined to the back surface 22 of the semiconductor element 2. The first inner heat conductor 51 and the second inner heat conductor 52 disposed inside the The first inner heat conductor 51 and the second inner heat conductor 52 are stacked in the direction (Z direction) in which the semiconductor element 2 and the first heat radiator 5 are aligned. The first inner heat conductor 51 includes a plurality of first graphite layers 511. The plurality of first graphite layers 511 are stacked in a first direction (X direction) which is a direction orthogonal to the direction (Z direction) in which the semiconductor element 2 and the first heat dissipation body 5 are arranged. The second inner heat conductor 52 includes a plurality of second graphite layers 521. The plurality of second graphite layers 521 are stacked in the direction (Z direction) in which the semiconductor element 2 and the first heat dissipation body 5 are aligned.

  According to this configuration, the heat generated by the operation of the semiconductor element 2 is dissipated by the first radiator 5. The heat generated in the semiconductor element 2 is conducted to the first outer heat conductor 53 joined to the semiconductor element 2, and subsequently the first inner heat conductor disposed inside the first outer heat conductor 53. The heat is conducted to the first and second inner heat conductors 52, and is conducted again to the first outer heat conductor 53 to be dissipated to the outside.

  The thermal conductivity of graphite is higher than the thermal conductivity of metals. The first heat radiator 5 can conduct heat more efficiently than the case of using only metal by providing the plurality of first graphite layers 511 and the plurality of second graphite layers 521.

  The plurality of first graphite layers 511 constituting the first inner heat conductor 51 have anisotropy in thermal conductivity. Each first graphite layer 511 does not conduct much heat in the first direction (X direction) in which the plurality of first graphite layers 511 are stacked. On the other hand, each first graphite layer 511 has high thermal conductivity in the direction (Y direction and Z direction) orthogonal to the first direction (X direction) in which the plurality of first graphite layers 511 are stacked. Conduct Therefore, in the first inner heat conductor 51, heat is conducted with high thermal conductivity in the direction (Z direction) in which the semiconductor element 2 and the first heat radiator 5 are aligned. In the first inner heat conductor 51, heat is conducted with high thermal conductivity in a second direction (Y direction) perpendicular to the Z direction and orthogonal to the first direction (X direction).

  Similarly, the plurality of second graphite layers 521 constituting the second inner heat conductor 52 have anisotropy in thermal conductivity. Each second graphite layer 521 does not conduct much heat in the direction (Z direction) in which the plurality of second graphite layers 521 are stacked. On the other hand, each second graphite layer 521 conducts heat with high thermal conductivity in the direction (X direction and Y direction) orthogonal to the direction (Z direction) in which the plurality of second graphite layers 521 are stacked. Do. Therefore, in the second inner heat conductor 52, the first direction (X direction) and the second direction (Y direction) are directions orthogonal to the direction (Z direction) in which the semiconductor element 2 and the first heat dissipation body 5 are aligned. Heat is conducted with high thermal conductivity.

  According to the above configuration, the heat generated in the semiconductor element 2 can be conducted to the first inner heat conductor 51 and the second inner heat conductor 52 by the metal first outer heat conductor 53. In addition, the direction (Z direction) in which the semiconductor element 2 and the first heat radiator 5 are aligned by the first inner heat conductor 51 and the second inner heat conductor 52, and the first direction (X direction). And the second direction (Y direction) can be conducted with high thermal conductivity. Further, the heat conducted by the first inner heat conductor 51 and the second inner heat conductor 52 can be dissipated in multiple directions by the first outer heat conductor 53. Therefore, according to the above configuration, the heat generated in the semiconductor element 2 is efficiently performed by the first outer heat conductor 53 of the first heat radiator 5, the first inner heat conductor 51, and the second inner heat conductor 52. Since the heat can be conducted and dissipated in multiple directions, the heat dissipation can be improved. When the stacking direction of the plurality of first graphite layers 511 and the stacking direction of the plurality of second graphite layers 521 coincide with each other, the heat conduction direction coincides with each other, so heat can be dissipated in multiple directions. It disappears.

  The semiconductor device 1 further includes a second heat sink 7 joined to the surface 21 of the semiconductor element 2. The second heat radiating body 7 has the same configuration as the first heat radiating body 5. Therefore, the heat dissipation can be improved not only on the back surface 22 side of the semiconductor element 2 but also on the surface 21 side opposite to that.

  As mentioned above, although one Example was described, a specific aspect is not limited to the said Example. In the following description, the same components as those in the above description will be assigned the same reference numerals and descriptions thereof will be omitted.

Second Embodiment
As shown in FIG. 5, in the semiconductor device 1 according to the second embodiment, the first outer heat conductor 53 of the first heat radiator 5 may be additionally provided with a protrusion 55 protruding outward. . The protrusion 55 is made of, for example, copper (Cu). The protrusion 55 may be formed of a metal other than copper (Cu). The protrusion 55 is fixed to the first metal body 531 of the first outer heat conductor 53. The protrusion 55 is formed integrally with or separately from the first metal body 531 of the first outer heat conductor 53. The protrusion 55 is sealed by a sealing resin 90. The protruding portion 55 protrudes in a first direction (X direction) orthogonal to the direction (Z direction) in which the semiconductor element 2 and the first radiator 5 are arranged. The protrusion 55 also protrudes in a second direction (Y direction) orthogonal to the first direction (X direction) (not shown).

  Similarly, the second outer heat conductor 73 of the second heat radiator 7 may additionally include a protruding portion 75 protruding outward. The protrusion 75 is made of, for example, copper (Cu). The protrusion 75 may be formed of a metal other than copper (Cu). The protrusion 75 is fixed to the first metal body 731 of the second outer heat conductor 73. The protrusion 75 is formed integrally with or separately from the first metal body 731 of the second outer heat conductor 73. The protrusion 75 is sealed by a sealing resin 90. The protruding portion 75 protrudes in a first direction (X direction) orthogonal to the direction (Z direction) in which the semiconductor element 2 and the second heat dissipation body 7 are arranged. The protrusion 75 also protrudes in a second direction (Y direction) orthogonal to the first direction (X direction) (not shown).

  Further, as shown in FIG. 6, the protrusion 55 of the first radiator 5 may project in the direction (Z direction) in which the semiconductor element 2 and the first radiator 5 are aligned. Similarly, the protrusion 75 of the second heat sink 7 may protrude in the direction (Z direction) in which the semiconductor element 2 and the second heat sink 7 are aligned.

  The heat capacity of graphite is smaller than the heat capacity of metal. Therefore, in the configuration in which the first heat radiating body 5 includes the plurality of first graphite layers 511 and the plurality of second graphite layers 521, the first heat radiating body 5 is not limited to the first case in which the first heat radiating body 5 includes only metal. The heat capacity of the radiator 5 is reduced. According to said structure, since the 1st outer side heat conductor 53 is equipped with the protrusion part 55 of metal, the heat capacity of the 1st thermal radiation body 5 can be improved. Therefore, when the heat generated in the semiconductor element 2 is conducted to the first radiator 5, it is possible to suppress the temperature of the first radiator 5 from rising sharply. The same applies to the second radiator 7.

  Further, in the semiconductor device 1 described above, the boundary portion 56 between the first metal body 531 and the second metal body 532 of the first outer heat conductor 53 exists on the upper surface 536 and the lower surface 537 of the first outer heat conductor 53. I did not. The boundary 56 between the first metal body 531 and the second metal body 532 is present on the side surface 538 of the first outer heat conductor 53. Therefore, the upper surface 536 and the lower surface 537 of the first outer heat conductor 53 can be made uniform. The same applies to the second outer heat conductor 73.

(Other embodiments)
Although the first inner heat conductor 51 is disposed closer to the semiconductor element 2 than the second inner heat conductor 52 in the above embodiment, the present invention is not limited to this configuration. On the contrary, in some embodiments, the second inner heat conductor 52 may be disposed closer to the semiconductor element 2 than the first inner heat conductor 51.

  Similarly, although the third inner heat conductor 71 is disposed closer to the semiconductor element 2 than the fourth inner heat conductor 72 in the above embodiment, the present invention is not limited to this configuration. Conversely, the fourth inner heat conductor 72 may be disposed closer to the semiconductor element 2 than the third inner heat conductor 71 in some embodiments.

  In the above embodiment, the plurality of second graphite layers 521 are stacked in the direction (Z direction) in which the semiconductor element 2 and the first heat dissipation body 5 are aligned, but the present invention is not limited to this configuration. . In some embodiments, the plurality of second graphite layers 521 are orthogonal to the direction (Z direction) in which the semiconductor element 2 and the first heat dissipation body 5 are aligned, and the first direction (X direction) It may be laminated in the second direction (Y direction) orthogonal to the above. The first direction (X direction) in which the plurality of first graphite layers 511 are stacked and the second direction (Y direction) in which the plurality of second graphite layers 521 are stacked are orthogonal to each other.

  Each second graphite layer 521 does not conduct much heat in the direction (Y direction) in which the plurality of second graphite layers 521 are stacked. On the other hand, each second graphite layer 521 conducts heat with high thermal conductivity in the direction (X direction and Z direction) orthogonal to the direction (Y direction) in which the plurality of second graphite layers 521 are stacked. Do. Therefore, in the second inner heat conductor 52, heat can be conducted with high thermal conductivity in the Z direction and the X direction. The heat can be conducted with high thermal conductivity in the X direction, the Y direction, and the Z direction by the first inner heat conductor 51 and the second inner heat conductor 52. In particular, heat can be efficiently conducted in the Z direction.

  Similarly, in the above embodiment, the plurality of fourth graphite layers 721 are stacked in the direction (Z direction) in which the semiconductor element 2 and the second heat dissipation body 7 are aligned, but the present invention is limited to this configuration. It is not a thing. In some embodiments, the plurality of fourth graphite layers 721 are orthogonal to the direction (Z direction) in which the semiconductor element 2 and the second heat dissipation body 7 are aligned, and the first direction (X direction) It may be laminated in the second direction (Y direction) orthogonal to the above. The first direction (X direction) in which the plurality of third graphite layers 711 are stacked and the second direction (Y direction) in which the plurality of fourth graphite layers 721 are stacked are orthogonal to each other. According to this configuration, similarly to the above, the third inner heat conductor 71 and the fourth inner heat conductor 72 can conduct heat with high thermal conductivity in the X direction, the Y direction, and the Z direction. it can. In particular, heat can be efficiently conducted in the Z direction.

  In the above embodiment, the boundary 56 between the first metal body 531 and the second metal body 532 of the first outer heat conductor 53 does not exist in the lower surface 537 of the first outer heat conductor 53. However, the present invention is not limited to this configuration. In some embodiments, a boundary 56 between the first metal body 531 and the second metal body 532 may be present on the lower surface 537 of the first outer heat conductor 53.

  Similarly, in the above embodiment, the boundary portion 76 between the first metal body 731 and the second metal body 732 of the second outer heat conductor 73 does not exist on the upper surface 737 of the second outer heat conductor 73. Although it was composition, it is not limited to this composition. In some embodiments, a boundary 76 between the first metal body 731 and the second metal body 732 may be present on the top surface 737 of the second outer heat conductor 73.

  In the case of manufacturing the semiconductor device 1 described above, the lower surface 537 of the first outer heat conductor 53 of the first heat radiator 5 is scraped by a machine tool before or after the first heat radiator 5 is bonded to the semiconductor element 2. Sometimes. Therefore, a cutting allowance may be provided on the lower surface 537 side of the first outer heat conductor 53.

  As shown in FIG. 7, the first outer heat conductor 53 may include a first metal body 531, a second metal body 532, and a third metal body 533. The first metal body 531, the second metal body 532, and the third metal body 533 are arranged in the Z direction from the side closer to the semiconductor element 2 toward the far side. In FIG. 7, the sealing resin 90 is omitted. The first metal body 531 is bonded to the semiconductor element 2. The first metal body 531 is disposed between the semiconductor element 2 and the second metal body 532. The first metal body 531 is bonded to the surface of the second metal body 532 on the side of the semiconductor element 2. The second metal body 532 is joined to the first metal body 531. The second metal body 532 is disposed between the first metal body 531 and the third metal body 533. The second metal body 532 is bonded to the surface of the first metal body 531 opposite to the semiconductor element 2 side. The second metal body 532 is bonded to the surface of the third metal body 533 on the side of the semiconductor element 2. The third metal body 533 is bonded to the second metal body 532. The third metal body 533 is bonded to the surface of the second metal body 532 opposite to the semiconductor element 2 side.

  The boundary 56 between the first metal body 531 and the second metal body 532 of the first outer heat conductor 53 does not exist on the upper surface 536 and the lower surface 537 of the first outer heat conductor 53. The boundary 56 between the first metal body 531 and the second metal body 532 is present on the side surface 538 of the first outer heat conductor 53.

  The boundary portion 57 between the second metal body 532 and the third metal body 533 of the first outer heat conductor 53 does not exist on the upper surface 536 and the lower surface 537 of the first outer heat conductor 53. The boundary portion 57 between the second metal body 532 and the third metal body 533 exists on the side surface 538 of the first outer heat conductor 53.

  In the above embodiment, the second heat radiating body 7 includes the second outer heat conductor 73, the third inner heat conductor 71, and the fourth inner heat conductor 72. It is not limited to the configuration. In other embodiments, the second heat sink 7 may not be provided with these configurations, and may be formed only of metal. The second radiator 7 is a solid metal body, and the third inner heat conductor 71 and the fourth inner heat conductor 72 are not disposed therein. The metal which comprises the 2nd heat radiating body 7 is copper (Cu) and aluminum (Al), for example. The second heat radiating body 7 is joined to the surface 21 of the semiconductor element 2 through the solders 92 and 93 and the conductive plate 3. The second heat radiating body 7 is joined to the surface electrode formed on the surface 21 of the semiconductor element 2. The second radiator 7 is in electrical communication with the surface electrode. According to this configuration, since the second heat radiating body 7 is a solid metal body, for example, when the semiconductor device 1 is inspected using ultrasonic waves or X-rays, the second heat radiating body 7 must be clearly confirmed. it can. In addition, since graphite is not used for the second radiator 7, the cost of the semiconductor device 1 can be reduced.

  In the above embodiment, the conductive plate 3 is disposed as a spacer between the semiconductor element 2 and the second heat radiator 7. However, the present invention is not limited to this configuration, and the conductive plate 3 may not be provided. In this case, the second heat radiator 7 is joined to the surface 21 of the semiconductor element 2 by the solder 92 without the solder 93 and the conductive plate 3. According to this configuration, since the conductive plate 3 is not interposed between the semiconductor element 2 and the second radiator 7, the contact area between the semiconductor element 2 and the second radiator 7 can be enlarged. Therefore, the heat dissipation area can be expanded when the heat generated in the semiconductor element 2 is dissipated, and the heat dissipation can be improved. Further, the thickness in the Z direction of the semiconductor device 1 can be reduced.

(First test example)
A test was conducted on the thermal conductivity of the first radiator 5 in the semiconductor device 1 described above. In the first test example, the content of titanium (Ti) in each of the brazing materials 96, 97, 98 in the first heat radiating body 5 is set to 3 to 5 wt%. In addition, the thickness in the Z direction of each brazing filler metal 96, 97, 98 was 50 μm. In this case, the thermal conductivity of the first heat radiating body 5 was measured by changing the proportion of graphite in the first heat radiating body 5. The measurement results are shown in FIG. As shown in FIG. 8, it is confirmed that the thermal conductivity of the first radiator 5 is significantly higher when the ratio of graphite in the first radiator 5 is 85 wt% or more than when it is less than 85 wt%. It was done. Moreover, when the ratio of the graphite in the 1st heat sink 5 is 87 wt% or more, it was confirmed that the heat conductivity of the 1st heat sink 5 is still higher than the case where it is less than 87 wt%. Moreover, when the ratio of the graphite in the 1st heat radiating body 5 is 93 wt% or more, it was confirmed that the thermal conductivity of the 1st heat radiating body 5 is still higher than the case where it is less than 93 wt%.

(Second test example)
In the second test example, the content of titanium (Ti) in each of the brazing materials 96, 97, 98 in the first heat radiating body 5 is 3 wt% or less. Further, the thickness in the Z direction of each brazing filler metal 96, 97, 98 was 25 μm or less. In this case, the thermal conductivity of the first heat radiating body 5 was measured by changing the proportion of graphite in the first heat radiating body 5. The measurement results are shown in FIG. As shown in FIG. 9, when the proportion of graphite in the first heat radiating body 5 is 60 wt% or more, it is confirmed that the thermal conductivity is similar to that in the case of 86 wt% or more in the above first test example. The Moreover, when the ratio of the graphite in the 1st heat radiating body 5 is 68 wt% or more, it was confirmed that the thermal conductivity of the 1st heat radiating body 5 is still higher than the case where it is less than 68 wt%. Moreover, when the ratio of the graphite in the 1st heat sink 5 is 74 wt% or more, it was confirmed that the heat conductivity of the 1st heat sink 5 is still higher than the case where it is less than 74 wt%.

  The technical elements disclosed in the present specification are listed below. The following technical elements are useful independently of one another.

  The semiconductor device may further include a second heat dissipator joined to a second surface opposite to the first surface of the semiconductor element. The second heat dissipating member includes a metal second outer heat conductor joined to the second surface of the semiconductor element, a third inner heat conductor disposed inside the second outer heat conductor, and And a fourth inner heat conductor disposed inside the outer heat conductor and stacked on the third inner heat conductor in the direction in which the semiconductor element and the second heat sink are aligned. Good. The third inner thermal conductor may comprise a plurality of third graphite layers. The fourth inner heat conductor may comprise a plurality of fourth graphite layers. The plurality of third graphite layers may be stacked in a third direction which is a direction orthogonal to the direction in which the semiconductor element and the second heat dissipation body are arranged. The plurality of fourth graphite layers may be stacked in a direction in which the semiconductor element and the second heat dissipating member are aligned, or in a fourth direction which is a direction perpendicular to the direction and perpendicular to the third direction.

  According to this configuration, the heat dissipation can be improved not only on the first surface side of the semiconductor element, but also on the second surface side opposite to that.

  The semiconductor element, the first radiator, and the second radiator may be sealed by a sealing resin.

  The first outer heat conductor may comprise an outwardly projecting projection.

  According to this configuration, the heat capacity of the first heat radiating body can be improved. Therefore, when the heat which arose in the semiconductor element is conducted to the 1st heat dissipation body, it can control that the temperature of the 1st heat dissipation body rises rapidly.

  The semiconductor device may further include a second heat dissipator joined to a second surface opposite to the first surface of the semiconductor element. The second radiator may be a solid metal body.

  According to this configuration, when the semiconductor device is inspected using, for example, ultrasonic waves or X-rays, the second radiator can be clearly confirmed.

  Note that the X direction, the Y direction, and the Z direction in the above-described embodiment are directions for convenience of description, and can be mutually changed.

  As mentioned above, although the specific example of this invention was described in detail, these are only an illustration and do not limit a claim. The art set forth in the claims includes various variations and modifications of the specific examples illustrated above. The technical elements described in the present specification or the drawings exhibit technical usefulness singly or in various combinations, and are not limited to the combinations described in the claims at the time of application. In addition, the techniques exemplified in the present specification or the drawings can simultaneously achieve a plurality of purposes, and achieving one of the purposes itself has technical utility.

1: Semiconductor Device 2: Semiconductor Element 5: First Radiator 7: Second Radiator 21: Surface 22: Back 51: First Inner Thermal Conductor 52: Second Inner Thermal Conductor 53: First Outer Thermal Conductor 55: projection 71: third inner heat conductor 72: fourth inner heat conductor 73: second outer heat conductor 75: protrusion 90: sealing resin 511: first graphite layer 521: second graphite layer 711 : Third graphite layer 721: Fourth graphite layer

Claims (5)

A semiconductor element,
A first heat dissipating body joined to the first surface of the semiconductor element;
The first radiator is
A first outer thermal conductor of metal bonded to the first surface of the semiconductor element;
A first inner heat conductor disposed inside the first outer heat conductor;
A second inner heat conductor disposed inside the first outer heat conductor and stacked on the first inner heat conductor in a direction in which the semiconductor element and the first heat dissipation body are aligned , And,
The first inner heat conductor comprises a plurality of first graphite layers,
The second inner heat conductor comprises a plurality of second graphite layers,
The plurality of first graphite layers are stacked in a first direction which is a direction orthogonal to the direction in which the semiconductor element and the first heat dissipation body are arranged,
The plurality of second graphite layers are stacked in a direction in which the semiconductor element and the first heat dissipating member are aligned, or in a second direction orthogonal to the direction and orthogonal to the first direction. Semiconductor devices. The semiconductor device further includes a second heat dissipating member joined to a second surface opposite to the first surface of the semiconductor element,
The second radiator is
A second outer thermal conductor of metal bonded to the second surface of the semiconductor element;
A third inner heat conductor disposed inside the second outer heat conductor;
And a fourth inner heat conductor disposed inside the second outer heat conductor and stacked on the third inner heat conductor in a direction in which the semiconductor element and the second heat radiator are aligned. , And,
The third inner heat conductor comprises a plurality of third graphite layers,
The fourth inner heat conductor comprises a plurality of fourth graphite layers,
The plurality of third graphite layers are stacked in a third direction which is a direction orthogonal to the direction in which the semiconductor element and the second heat dissipation body are arranged,
The plurality of fourth graphite layers are stacked in a direction in which the semiconductor element and the second heat radiator are aligned, or in a direction orthogonal to the direction and a fourth direction orthogonal to the third direction. The semiconductor device according to claim 1. The semiconductor device further includes a second heat dissipating member joined to a second surface opposite to the first surface of the semiconductor element,
The semiconductor device according to claim 1, wherein the second radiator is a solid metal body.   The semiconductor device according to claim 2, wherein the semiconductor element, the first heat radiating body, and the second heat radiating body are sealed by a sealing resin. The semiconductor device according to any one of claims 1 to 4, wherein the first outer heat conductor includes an outwardly projecting protrusion.

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