JP2012151172A - Semiconductor device and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently radiate heat generated in a semiconductor device to the exterior.SOLUTION: A semiconductor device 1 comprises: a semiconductor element 3 mounted on a lead frame 2; a first heat transfer layer 4 provided in the semiconductor element 3; a second heat transfer layer 5 connecting with the first heat transfer layer 4; a third heat transfer layer 6 connecting with the second heat transfer layer 5; and a resin layer 7. The resin layer 7 seals the semiconductor element 3, the first heat transfer layer 4, and the second heat transfer layer 5, and the third heat transfer layer 6 is exposed from the resin layer 7. Heat generated from the semiconductor element 3 is efficiently transferred to the first heat transfer layer 4, the second heat transfer layer 5, and the third heat transfer layer 6 to be radiated to the exterior from the third heat transfer layer 6 exposed from the resin layer 7.

Description

  The present invention relates to a semiconductor device and a manufacturing method thereof.

Conventionally, methods for reducing the thermal resistance of a semiconductor device and suppressing overheating have been proposed.
For example, the present invention relates to a semiconductor device in which a semiconductor element mounted on a lead frame is sealed with a resin layer, a technique for sealing a semiconductor element with a resin layer containing a filler having relatively high thermal conductivity, and a resin for sealing a semiconductor element A technique for thinning the layer is known. In addition, a technology for connecting a heat sink to a lead frame on which a semiconductor element is mounted and sealing the resin plate with a resin layer so that the heat sink is exposed, and a projection surface provided on the heat sink is a resin film on the semiconductor element. There is also known a technique of sealing with a resin layer so that the heat dissipation plate is exposed.

  Further, regarding the reduction of thermal resistance of a semiconductor device, a semiconductor element is embedded in a first multilayer wiring layer on a ceramic substrate, a second multilayer wiring layer is bonded thereon, and a heat sink formed thereon is used as a second multilayer. A technique of connecting to a semiconductor element with a lead electrode penetrating the wiring layer is also known.

JP 2000-269388 A JP-A-5-63113 JP-A-7-183433

  In a semiconductor device in which a semiconductor element mounted on a lead frame is sealed with a resin layer, in some cases, heat generated in the semiconductor element cannot be efficiently radiated to the outside by the above-described technology. For example, there is a possibility that sufficient heat dissipation cannot be performed for an increase in the amount of heat generated per unit area of the semiconductor element due to high integration and an increase in the amount of heat generated when a power semiconductor element is used.

  According to an aspect of the present invention, a lead frame, a semiconductor element mounted on the lead frame, a first heat transfer layer provided in the semiconductor element, and a first heat transfer layer connected to the first heat transfer layer. 2 heat transfer layers, a third heat transfer layer connected to the second heat transfer layer, the semiconductor element, the first heat transfer layer, and the second heat transfer layer are sealed, and the third heat transfer layer is sealed. A semiconductor device is provided that includes a resin layer from which the layer is exposed.

  According to the disclosed semiconductor device, it is possible to efficiently dissipate heat generated in the semiconductor element to the outside.

It is a figure which shows the structural example of a semiconductor device. It is a figure showing an example of a semiconductor device concerning a 1st embodiment. It is a figure which shows another example of the semiconductor device which concerns on 1st Embodiment. It is explanatory drawing (the 1) of model calculation. It is explanatory drawing (the 2) of model calculation. It is a figure which shows the relationship between a heat-transfer area and an equivalent thermal conductivity. It is a figure which shows an example of the formation method of the semiconductor device which concerns on 1st Embodiment. It is FIG. (1) which shows the example of the internal structure of a semiconductor device. FIG. 3 is a second diagram illustrating an example of the internal structure of a semiconductor device. It is a figure which shows an example of the semiconductor device which concerns on 2nd Embodiment. It is a figure which shows an example of the formation method of the semiconductor device which concerns on 2nd Embodiment. It is a figure which shows another example of the semiconductor device which concerns on 2nd Embodiment. It is a figure (the 1) which shows the modification of a heat exchanger layer. It is a figure (the 2) which shows the modification of a heat exchanger layer. It is a figure (the 3) which shows the modification of a heat exchanger layer. It is a figure (the 4) which shows the modification of a heat exchanger layer.

FIG. 1 is a diagram illustrating a configuration example of a semiconductor device.
A semiconductor device 1 shown in FIG. 1 includes a lead frame 2, a semiconductor element 3, a first heat transfer layer 4, a second heat transfer layer 5, a third heat transfer layer 6, and a resin layer 7.

  The semiconductor element 3 is mounted on the lead frame 2. The first heat transfer layer 4 is provided, for example, on the surface of the semiconductor element 3 mounted on the lead frame 2. The first heat transfer layer 4 may be connected to a further heat transfer layer provided further inside the semiconductor element 3. The second heat transfer layer 5 is connected to the first heat transfer layer 4, and the third heat transfer layer 6 is connected to the second heat transfer layer 5. The resin layer 7 seals the semiconductor element 3, the first heat transfer layer 4, and the second heat transfer layer 5 on the lead frame 2 so that the surface of the third heat transfer layer 6 is exposed.

The first heat transfer layer 4, the second heat transfer layer 5, and the third heat transfer layer 6 are made of a material having a higher thermal conductivity than that of the resin layer 7.
In the semiconductor device 1 having such a configuration, for example, heat generated in the semiconductor element 3 is transferred to the first heat transfer layer 4, and heat transferred to the first heat transfer layer 4 is transferred to the second heat transfer layer 4. The heat transferred to the heat layer 5 and transferred to the second heat transfer layer 5 is transferred to the third heat transfer layer 6. In the semiconductor device 1, the second heat transfer layer 5 is connected to the first heat transfer layer 4 provided in the semiconductor element 3, and the third heat transfer layer 6 is connected to the second heat transfer layer 5. 3 can be efficiently transferred to the third heat transfer layer 6. Furthermore, since the third heat transfer layer 6 is exposed from the resin layer 7 in the semiconductor device 1, the heat transferred to the third heat transfer layer 6 can be efficiently radiated to the outside.

  Note that the heat transfer and heat release paths of the heat generated in the semiconductor element 3 are transferred in this order through the first heat transfer layer 4, the second heat transfer layer 5, and the third heat transfer layer 6 in this order. The path is not limited to the heat radiation from the heat layer 6 to the outside. For example, heat is transferred from the semiconductor element 3, the first heat transfer layer 4, or the second heat transfer layer 5 to the resin layer 7, transferred from the resin layer 7 to the third heat transfer layer 6, and radiated from there to the outside. There is also a route to be done. There is also a path through which the heat transferred to the resin layer 7 is radiated from the resin layer 7 to the outside.

  In the semiconductor device 1, since the semiconductor element 3 and the third heat transfer layer 6 exposed from the resin layer 7 are connected using the first heat transfer layer 4 and the second heat transfer layer 5, The heat of the semiconductor element 3 can be efficiently transferred to the third heat transfer layer 6 and radiated to the outside.

  Further, by providing the first heat transfer layer 4 in the semiconductor element 3, the heat generated in the semiconductor element 3 can be efficiently transferred to the second heat transfer layer 5 and the third heat transfer layer 6. . Furthermore, by making the 2nd heat transfer layer 5 and the 3rd heat transfer layer 6 into a different body, the thing of the various forms as mentioned later is applicable as the 2nd heat transfer layer 5, for example.

Hereinafter, the semiconductor device will be described in more detail.
FIG. 2 is a diagram illustrating an example of the semiconductor device according to the first embodiment. 2A and 2B are diagrams schematically illustrating a main part of an example of the semiconductor device according to the first embodiment, in which FIG. 2A is a cross-sectional view and FIG. 2B is a plan view.

  A semiconductor device (semiconductor package) 10A illustrated in FIG. 2 includes a lead frame 11 and a semiconductor element (chip) 12 (illustrated by a dotted line in FIG. 2B) mounted on the lead frame 11. The semiconductor element 12 is bonded onto the lead frame 11 using a die bond material 13. The electrode pad 12a provided on the surface of the semiconductor element 12 is connected to the lead frame 11 by a wire 14, and the semiconductor element 12 and the lead frame 11 are electrically connected. For the die bond material 13, for example, a material having adhesiveness and thermal conductivity such as silver (Ag) paste or solder can be used. For the wire 14, for example, a material such as gold (Au) or aluminum (Al) can be used.

  A first heat transfer layer 15 (illustrated by a dotted line in FIG. 2B) is provided inside the semiconductor element 12. The first heat transfer layer 15 is provided on the upper surface side of the semiconductor element 12, avoiding the region where the electrode pads 12 a are disposed. A sheet-like heat transfer member can be used for the first heat transfer layer 15. For the first heat transfer layer 15, a metal material, a carbon material, or a ceramic material can be used. For example, the first heat transfer layer 15 is made of a material having higher thermal conductivity than the sealing resin.

  The first heat transfer layer 15 can be formed, for example, by forming the semiconductor element 12 inside the semiconductor element 12. For example, when the electrode pad 12a is formed, the first heat transfer layer 15 is formed in the predetermined region of the same layer as the electrode pad 12a using the same material as the electrode pad 12a. At this time, another heat transfer layer is formed below the first heat transfer layer 15 together with, for example, wiring and vias, and the first heat transfer layer 15 is formed so as to be connected to the heat transfer layer. You may make it do.

  A second heat transfer layer 16 (illustrated by a dotted line in FIG. 2B) is connected to the first heat transfer layer 15. For example, as shown in FIG. 2, the second heat transfer layer 16 is connected to the first heat transfer layer 15 using a first adhesive layer 18.

  For the second heat transfer layer 16, for example, a metal material, a carbon material, or a ceramic material can be used. For example, a material having higher thermal conductivity than the sealing resin can be used for the second heat transfer layer 16.

  The first adhesive layer 18 can be made of a material having adhesiveness and thermal conductivity, such as Ag paste or solder. Depending on the combination of materials of the first heat transfer layer 15 and the second heat transfer layer 16, the first heat transfer layer 15 and the second heat transfer layer 16 are connected without using the first adhesive layer 18. It is also possible to do.

  Various shapes can be used for the second heat transfer layer 16. Here, as an example, one second heat transfer layer 16 having a shape (U-shape) in which a flexible sheet-like heat transfer member such as a flexible sheet made of a predetermined material is folded in two is used. . One end side (lower side) of the second heat transfer layer 16 having such a folded shape is connected to the upper surface of the first heat transfer layer 15 via the first adhesive layer 18.

  A third heat transfer layer 17 is connected to the other end side (upper side) of the second heat transfer layer 16 having a folded shape. For example, as shown in FIG. 2, the third heat transfer layer 17 is connected to the second heat transfer layer 16 using a second adhesive layer 19.

  A sheet-like heat transfer member can be used for the third heat transfer layer 17. For the third heat transfer layer 17, for example, a metal material, a carbon material, or a ceramic material can be used. For example, a material having higher thermal conductivity than the sealing resin can be used for the third heat transfer layer 17.

  The second adhesive layer 19 can be made of a material having adhesiveness and thermal conductivity such as Ag paste or solder. Depending on the combination of materials of the second heat transfer layer 16 and the third heat transfer layer 17, the second heat transfer layer 16 and the third heat transfer layer 17 are connected without using the second adhesive layer 19. It is also possible to do.

As described above, the first heat transfer layer 15, the second heat transfer layer 16, and the third heat transfer layer 17 are thermally connected to the semiconductor element 12 mounted on the lead frame 11.
The semiconductor element 12, the wire 14, the first heat transfer layer 15, and the second heat transfer layer 16 bonded to the lead frame 11 with the die bond material 13 are sealed with a resin layer 20. The resin layer 20 is provided so that, for example, the upper surface of the third heat transfer layer 17 is exposed. For the resin layer 20, for example, a resin (sealing resin) containing a predetermined non-conductive filler can be used. Note that a filler having high thermal conductivity may be used. The resin layer 20 can be formed by a molding method using a predetermined mold.

  In the semiconductor device 10 </ b> A having the above-described configuration, the heat generated in the semiconductor element 12 is efficiently transferred to the first heat transfer layer 15, the second heat transfer layer 16, and the third heat transfer layer 17, and the resin layer 20. It is possible to efficiently dissipate heat from the third heat transfer layer 17 exposed from the outside.

  In the semiconductor device 10 </ b> A, the second heat transfer layer 16 has a folded shape and is connected to the first heat transfer layer 15 and the third heat transfer layer 17 on the outer surfaces of the folded ends. Therefore, while securing the heat transfer path in the stacking direction at the curved or bent portion (folded portion) of the second heat transfer layer 16, the first heat transfer layer 15 and the third heat transfer layer 17 are formed on the surfaces of both ends. A relatively large contact area (heat transfer area) can be secured. Thereby, efficient heat transfer from the semiconductor element 12 to the third heat transfer layer 17 is realized.

  Furthermore, when the resin layer 20 is formed by using a relatively flexible material for the second heat transfer layer 16 connecting the first heat transfer layer 15 and the third heat transfer layer 17, the second heat transfer layer 16 is used. 16 exhibits cushioning properties, and the impact on the semiconductor element 12 due to resin flow during resin sealing is suppressed.

  For example, at the time of resin sealing, the assembly before sealing is sandwiched between the upper mold and the lower mold of the mold, the sealing resin is press-fitted into the space between them, and the sealing resin flows in the lateral direction. The solid is sealed with a sealing resin. Due to the resin flow in the lateral direction at this time, a certain amount of load is applied to the third heat transfer layer 17 and the second heat transfer layer 17. In response to the load, the second heat transfer layer 16 deforms in the lateral direction due to its flexibility, with one end fixed to the first heat transfer layer 15 and the semiconductor element 12 side.

  If an inflexible material is used for the second heat transfer layer 16, a load due to resin flow at the time of resin sealing is applied to the semiconductor element 12 side, which may cause damage or breakage of the semiconductor element 12. There is.

  On the other hand, when the second heat transfer layer 16 having flexibility as described above is used, it is possible to reduce the load applied to the semiconductor element 12 due to the resin flow at the time of resin sealing due to the cushion effect due to the deformation. become. Thereby, damage and breakage of the semiconductor element 12 can be suppressed, and the reliability and yield of the semiconductor device 10A can be improved.

In addition, although the case where one second heat transfer layer 16 is provided between the first heat transfer layer 15 and the third heat transfer layer 17 is illustrated here, a plurality of second heat transfer layers 16 may be provided. Is possible.
FIG. 3 is a diagram showing another example of the semiconductor device according to the first embodiment. FIGS. 3A and 3B are diagrams schematically showing main parts of another example of the semiconductor device according to the first embodiment, in which FIG. 3A is a cross-sectional view and FIG. 3B is a plan view.

  The semiconductor device 10 </ b> Aa shown in FIG. 3 has a structure in which a plurality of second heat transfer layers 16 are provided between the first heat transfer layer 15 and the third heat transfer layer 17. In this case, each of the second heat transfer layers 16 can have the shape and material as described above, and each second heat transfer layer 16 is connected to the first heat transfer layer via the first adhesive layer 18. 15 and connected to the third heat transfer layer 17 via the second adhesive layer 19.

As described above, even when the plurality of second heat transfer layers 16 are provided, the same heat transfer and heat dissipation effects as those described above and a load reduction effect on the semiconductor element 12 during resin sealing can be obtained.
By the way, when the first heat transfer layer 15 and the third heat transfer layer 17 are connected by vias without using the second heat transfer layer 16 as described above, there may be restrictions on the heat transfer and heat dissipation effects. Here, the thermal conductivity of the structure using the second heat transfer layer 16 as described above is compared with the case of the structure using the via. Therefore, the following model calculation is performed for each case.

4 and 5 are explanatory diagrams of model calculation. 4 and 5, (A) is an explanatory diagram of a model of a structure using a second heat transfer layer, and (B) is an explanatory diagram of a model of a structure using vias.
Here, first, as shown in FIG. 4 (A), the structure of one section of the region of the second heat transfer layer 16 and the resin layer 20 sealing it is equivalent using the equation (1). Calculate the thermal conductivity. For comparison, also for the via structure, assuming the cross section of the structure in which the second heat transfer layer 16 is replaced with a via and the via 100 is disposed in the resin layer 20 as shown in FIG. Using equation (1), the equivalent thermal conductivity is calculated. The second heat transfer layer 16 and the via 100 are made of the same material.

λ _eq = (λ _P × A _P + λ _R × A _R ) / (A _P + A _R ) (1)
In this equation (1), λ _eq is the equivalent thermal conductivity, λ _P is the thermal conductivity of the second heat transfer layer 16 or the via 100, λ _R is the thermal conductivity of the resin layer 20, and A _P is the second heat transfer. sectional area of the layer 16 or via 100, a _R is the cross-sectional area of the resin layer 20.

  It is assumed that the thicknesses of the portions (the folded ends) where the second heat transfer layer 16 is connected to the first heat transfer layer 15 and the third heat transfer layer 17 are sufficiently thin. In that case, the volume of the heat transfer path is the sectional area A1 (heat transfer area) × height H (between the first heat transfer layer 15 and the second heat transfer layer 16) as shown in FIG. The thickness of the resin layer 20 can be considered. If the second heat transfer layer 16 is simply replaced with a via 100 as shown in FIG. 5 (B), both have the same height H. Therefore, depending on the cross-sectional areas A1 and A2 (heat transfer area) regardless of the volume. Thermal conductivity can be compared.

  As a specific model calculation example, the thickness (sheet thickness) of the second heat transfer layer 16 is 150 μm, the width (sheet width) is 300 μm, and the pitch is 400 μm on the semiconductor element 12 having a planar size of 5 mm × 5 mm. Thus, a plurality of folded second heat transfer layers 16 are arranged. In this case, a total of 49 (about 50) second heat transfer layers 16 can be arranged, 7 vertically and 7 horizontally.

  The via 100 is formed by, for example, a build-up process in which a process of attaching a resin sheet (corresponding to a part of the resin layer 20) on the semiconductor element 12, drilling by laser processing, and filling by plating is repeated. Is assumed. The maximum diameter of the via 100 that can be drilled and can be filled with flat plating is 200 μm. If the vias 100 having such a size are arranged on the semiconductor element 12 having a planar size of 5 mm × 5 mm at a pitch of 400 μm, the vertical number of the vias is 7 and the horizontal is 7, for a total of 49 (about 50). The via 100 can be arranged.

  FIG. 6 shows the relationship between the heat transfer area and the equivalent thermal conductivity. In FIG. 6, the relationship between the heat transfer area of the second heat transfer layer 16 and the equivalent heat conductivity is indicated by a solid line (heat transfer layer structure), and the relationship between the heat transfer area of the via 100 and the equivalent heat conductivity is indicated by a dotted line ( (Via structure). The numbers 12, 25, and 50 shown in FIG. 6 indicate the number of second heat transfer layers 16 and the number of vias 100, respectively.

From FIG. 6, the second heat transfer layer 16 can obtain a larger heat transfer area and higher heat conductivity than when the same number of vias 100 are used. In the case of the via 100, in the above model calculation, the heat transfer area can be secured only up to 1.6 mm ² which is the heat transfer area of 50 vias 100 according to the formation rule. On the other hand, in the case of the second heat transfer layer 16, a larger heat transfer area can be secured even when the same 50 pieces are arranged.

  Therefore, the second heat transfer layer 16 can be suitably used even when a semiconductor element 12 having a large heat generation amount such as a power semiconductor is used. Further, since the second heat transfer layer 16 has a high degree of freedom in sheet thickness, sheet width, and number, it is possible to select an optimal form according to the type of semiconductor element 12 to be used, required heat dissipation characteristics, and the like. it can.

Next, a method for forming a semiconductor device according to the first embodiment will be described.
FIG. 7 is a diagram illustrating an example of a method for forming a semiconductor device according to the first embodiment.
First, as shown in FIG. 7A, the semiconductor element 12 having the first heat transfer layer 15 provided in a predetermined region is die-bonded face-up on the lead frame 11 using a die bonding material 13. Next, the wire 14 is electrically connected between the electrode pad 12 a of the semiconductor element 12 and the lead frame 11 (lead portion (outer lead)). The electrode pad 12a and the lead frame 11 may be electrically connected using a wedge bonding method.

  Next, the second heat transfer layer 16 which has been folded in advance and the sheet-like third heat transfer layer 17 provided thereon are connected. In that case, for example, as shown in FIG. 7B, the first adhesive layer 18 is provided on the upper surface of the first heat transfer layer 15, and the second adhesive layer 19 is provided on the lower surface of the third heat transfer layer 17. Then, as shown in FIG. 7C, one end side of the folded second heat transfer layer 16 is connected to the first heat transfer layer 15 via the first adhesive layer 18, and the other The third heat transfer layer 17 is connected to the end portion side through the second adhesive layer 19.

  After the process up to the connection of the third heat transfer layer 17 as shown in FIG. 7C, the obtained assembly is set in the mold (between the upper mold and the lower mold) of the resin sealing (molding) device. Then, the semiconductor element 12, the wire 14, the lead frame 11 (outer lead), the first heat transfer layer 15 and the second heat transfer layer 16 are sealed with a thermosetting sealing resin. In that case, sealing is performed so that the upper surface of the third heat transfer layer 17 is exposed. After sealing, by removing the mold, an assembly sealed with the resin layer 20 as shown in FIG. 7D is obtained.

  At the time of sealing, for example, the resin is press-fitted between the upper mold and the lower mold, and fills the assembly while flowing in the lateral direction. Due to the flow of the resin, a load may be applied to the second heat transfer layer 16 and the third heat transfer layer 17, but the second heat transfer layer 16 absorbs such a load by deformation and is applied to the semiconductor element 12 side. The load burden can be reduced.

After sealing, after removing the mold, the outer lead of the lead frame 11 is cut to obtain the semiconductor device 10A.
Here, one semiconductor device 10A is illustrated. Of course, a plurality of semiconductor elements 12 are mounted on one lead frame 11, and the first heat transfer layer 15, the second heat transfer layer 16, and the third heat transfer layer 17 are connected to each, and the whole is sealed, A plurality of semiconductor devices 10A may be obtained by cutting the leads and separating them individually.

  7 illustrates the method of forming the semiconductor device 10A (FIG. 2) provided with one second heat transfer layer 16, the semiconductor device 10Aa (FIG. 3) provided with a plurality of second heat transfer layers 16 is also illustrated. It can be formed according to the example shown in FIG.

  An example of the internal structure of a semiconductor device formed by using the method shown in FIG. 7 is shown in FIGS. 8 and 9 schematically show the mounting region of the semiconductor element 12 of the lead frame 11.

  The semiconductor element 12 includes two transistor portions 12b and gate, source, and drain electrode pads 12a. The gate electrode pad 12 a is connected to the gate lead portion 11 a of the lead frame 11 by a gate wiring 14 a (wire 14). The source electrode pad 12 a is connected to the source lead portion 11 b of the lead frame 11 by a source wiring 14 b (wire 14). The drain electrode pad 12a is connected to the drain lead portion 11c of the lead frame 11 by a drain wiring 14c.

  FIG. 8 illustrates a structure in which the first heat transfer layer 15 is provided on each transistor portion 12b and the second heat transfer layer 16 is connected thereto. And although illustration is abbreviate | omitted here, the 3rd heat transfer layer 17 is connected on each 2nd heat transfer layer 16, respectively.

  FIG. 9 illustrates a structure in which a plurality of second heat transfer layers 16 are connected to the first heat transfer layer 15 provided on each transistor portion 12b. And although illustration is abbreviate | omitted here, the 3rd heat transfer layer 17 is each connected so that the some 2nd heat transfer layer 16 on each 1st heat transfer layer 15 may be covered.

  The semiconductor device according to the first embodiment has been described above. In the above description, the case where the second heat transfer layer 16 is connected to the first heat transfer layer 15 and the third heat transfer layer 17 has been described, but the second heat transfer layer 16 is further connected to the lead frame 11. Is also possible.

FIG. 10 is a diagram illustrating an example of a semiconductor device according to the second embodiment.
The semiconductor device (semiconductor package) 10B shown in FIG. 10 has a structure in which the second heat transfer layer 16 is extended to the end of the resin layer 20 and connected to the lead frame 11 via the heat transfer member 21. is doing.

  The second heat transfer layer 16 extended to the end of the resin layer 20 and one end of the heat transfer member 21 are connected using a third adhesive layer 22, for example, as shown in FIG. Moreover, the other end part of the heat-transfer member 21 and the lead frame 11 are connected using the 4th contact bonding layer 23, as shown, for example in FIG. Depending on the combination of the materials of the second heat transfer layer 16 and the heat transfer member 21, the second heat transfer layer 16 and the heat transfer member 21 can be connected without using the third adhesive layer 22. Further, depending on the combination of the materials of the heat transfer member 21 and the lead frame 11, it is possible to connect the heat transfer member 21 and the lead frame 11 without using the fourth adhesive layer 23.

  According to such a semiconductor device 10B, the heat generated in the semiconductor element 12 is sequentially transferred to the first heat transfer layer 15, the second heat transfer layer 16, and the third heat transfer layer 17, and the second heat transfer layer 17 is also transferred. Heat can be transferred from the heat layer 16 to the lead frame 11 via the heat transfer member 21. Thus, the heat transferred from the semiconductor element 12 to the second heat transfer layer 16 is exposed from the lead frame 11 or from the resin layer 20 in addition to the third heat transfer layer 17 exposed from the resin layer 20. Heat can be radiated from the heat transfer member 21 to the outside, and the heat dissipation effect can be further enhanced.

The semiconductor device 10B having the above configuration can be formed as follows, for example.
FIG. 11 is a diagram illustrating an example of a method of forming a semiconductor device according to the second embodiment.

  As shown in FIG. 11A, after the semiconductor element 12 provided with the first heat transfer layer 15 in a predetermined region is die-bonded on the lead frame 11 with the die bonding material 13, the electrode pads 12a of the semiconductor element 12 and the leads The frames 11 are electrically connected by wires 14.

  Next, the second heat transfer layer 16 and the sheet-like third heat transfer layer 17 which are formed in a folded shape so that one end side is long in advance are connected. For example, as shown in FIG. 11A, a first adhesive layer 18 and a second adhesive layer 19 are provided on the first heat transfer layer 15 and the third heat transfer layer 17, respectively. Then, as shown in FIG. 11B, the shorter end of the folded second heat transfer layer 16 is connected to the first heat transfer layer 15 via the first adhesive layer 18, and the longer one is connected. The third heat transfer layer 17 is connected to the end portion side through the second adhesive layer 19.

  Furthermore, as shown in FIG. 11B, a sacrificial layer 24 is formed at the end portion on the longer end side of the second heat transfer layer 16. The sacrificial layer 24 can be formed using, for example, a resist. The sacrificial layer 24 may be formed in advance on a predetermined portion of the second heat transfer layer 16 before connection with the first heat transfer layer 15 and the third heat transfer layer 17.

  Next, the assembly obtained as described above is set in a mold (between the upper mold and the lower mold) of the molding apparatus, and the semiconductor element 12, the wire 14, the lead frame 11 (outer lead), and the first transmission. The heat layer 15 and the second heat transfer layer 16 are sealed with a sealing resin. In that case, sealing is performed so that the third heat transfer layer 17 and the sacrificial layer 24 are exposed. After sealing, the assembly sealed with the resin layer 20 as shown in FIG. 11C is obtained by removing the mold.

  Next, the sacrificial layer 24 exposed in the assembly after sealing is removed. Then, the leading end portion of the second heat transfer layer 16 exposed after removal of the sacrificial layer 24 and the lead frame 11 are connected by the heat transfer member 21 as shown in FIG. Here, the third adhesive layer 22 is provided at the tip of the exposed second heat transfer layer 16, the fourth adhesive layer 23 is provided on the lead frame 11, and both ends of the heat transfer member 21 are connected to the third adhesive layer 22. The second heat transfer layer 16 and the lead frame 11 are connected to each other through the fourth adhesive layer 23.

Thereafter, the outer lead of the lead frame 11 is cut to obtain the semiconductor device 10B.
Here, after the resin layer 20 is formed, the second heat transfer layer 16 and the lead frame 11 are connected by the heat transfer member 21. In addition, the resin layer 20 is formed so that the second heat transfer layer 16 and the lead frame 11 are connected by the heat transfer member 21 before the resin layer 20 is formed, and then the heat transfer member 21 is also sealed. May be formed. Even in the structure thus obtained, the second heat transfer layer 16 is connected to the lead frame 11 through the heat transfer member 21 in the resin layer 20, so that a high heat dissipation effect can be obtained. Is possible.

  Here, the second heat transfer layer 16 is connected to the lead frame 11 using the heat transfer member 21, but one end of the second heat transfer layer 16 is connected to the lead frame without using the heat transfer member 21. It can be extended to 11 and connected to the lead frame 11.

FIG. 12 is a diagram illustrating another example of the semiconductor device according to the second embodiment.
In the semiconductor device 10Ba shown in FIG. 12, one end portion (tip portion) of the folded second heat transfer layer 16 is further bent, and the bent portion is formed on the lead frame 11 with the fourth adhesive layer 23. It has the structure connected via.

  In the case of such a structure, the second heat transfer layer 16 that has been folded and bent at the tip so as to have a shape as shown in FIG. 12 is used as the first heat transfer layer 15 and the third heat transfer layer. It connects to the thermal layer 17 and the lead frame 11, respectively, and seals so that the bent tip part may be exposed. Alternatively, the second heat transfer layer 16 (before bending the tip end portion) that has been folded up is connected to the first heat transfer layer 15 and the third heat transfer layer 17 so that the tip end portion to be bent is exposed. After sealing, the exposed tip is bent and connected to the lead frame 11.

  12 illustrates the case where the tip of the second heat transfer layer 16 is exposed from the resin layer 20 and connected to the lead frame 11, but the second heat transfer including the connection portion with the lead frame 11 is illustrated. The entire layer 16 may be sealed with the resin layer 20. Even with such a structure, it is possible to obtain a high heat dissipation effect by connecting the second heat transfer layer 16 to the lead frame 11.

  Although the semiconductor devices according to the first and second embodiments have been described above, the second heat transfer layer 16 used for these semiconductor devices is a folded or folded sheet-like material as described above. It is not limited to what includes a part. For example, a material in which a linear material is folded or a shape including a folded portion is provided as a second heat transfer layer connected to the first heat transfer layer 15 and the third heat transfer layer 17. May be.

  Further, the second heat transfer layer connected to the first heat transfer layer 15 and the third heat transfer layer 17 in this way is limited to the folded shape as described above or a shape including such a shape portion. Not. For example, the second heat transfer layer connected to the first heat transfer layer 15 and the third heat transfer layer 17 may have a form as shown in FIGS. 13 to 16 below.

  For example, as the second heat transfer layer connected to the first heat transfer layer 15 and the third heat transfer layer 17, a step-shaped second heat transfer layer 16a without folding as shown in FIG. A second heat transfer layer 16b having a plurality of folded shapes as shown in FIG. 14 may be used. Such 2nd heat transfer layers 16a and 16b can be formed using a sheet-like material or a linear material.

  Further, as the second heat transfer layer connected to the first heat transfer layer 15 and the third heat transfer layer 17, as shown in FIGS. 15 and 16, a porous second transfer layer into which the sealing resin can flow is used. Thermal layers 16c and 16d can also be used. For example, the second heat transfer layer 16c shown in FIG. 15 is obtained by knitting a linear material into a mesh shape. The second heat transfer layer 16d shown in FIG. 16 is obtained by forming a large number of pores in a block-shaped material.

  Even if the second heat transfer layers 16a to 16d as exemplified above are provided between the first heat transfer layer 15 and the third heat transfer layer 17 and connected to them, they are generated in the semiconductor element 12 as described above. Heat can be efficiently radiated to the outside.

  In any of the second heat transfer layers 16a to 16d, a heat transfer member for connecting to the lead frame 11 can be used to connect to the lead frame 11 outside or inside the resin layer 20. is there. Further, in any case of the second heat transfer layers 16 a to 16 d, a part of the second heat transfer layers 16 a to 16 d can be extended to the outside of the resin layer 20, or extended inside, and the extended tip can be connected to the lead frame 11. is there.

As the second heat transfer layer, a spiral type (coil shape), a bellows type, or the like can be used in addition to those exemplified above.
In the second heat transfer layer, heat transfer from the first heat transfer layer 15 to the third heat transfer layer 17 is possible, and a cushioning property that absorbs a load caused by resin flow at the time of resin sealing, Alternatively, it is possible to apply a wide range of materials that do not hinder the resin flow even if they do not exhibit cushioning properties.

For the second heat transfer layer, metal or alloy foil, ribbon, wire, carbon fiber, carbon nanotube, or various ceramics can be used.
Examples and comparative examples are described below.
<Example>
A semiconductor device 10Aa (FIG. 3) having a plurality of second heat transfer layers 16 was formed. Here, a semiconductor element 12 having a planar size of 5 mm × 5 mm is used, and a copper (Cu) flexible sheet having a sheet thickness of 150 μm and a sheet width of 300 μm is formed between the first heat transfer layer 15 and the third heat transfer layer 17. Forty-eight second heat transfer layers 16 having a folded shape of 1 mm were arranged at a pitch of 400 μm. As a result of measuring the thermal resistance of the entire semiconductor device 10Aa during the operation of the semiconductor element 12, it was 0.5 ° C./W or less. As a result of trial calculation of the equivalent thermal conductivity of the entire semiconductor device 10Aa, it was 61 (arbitrary unit).
<Comparative example>
A semiconductor device was formed by replacing the second heat transfer layer 16 of the above example with a via. Here, a build-up process of applying a resin sheet having a thickness of 200 μm, drilling with a laser having a diameter of 200 μm, a pitch of 400 μm, and filling a hole with plating is repeated five times, and 49 vias are formed on the first heat transfer layer 15. And the third heat transfer layer 17 was disposed thereon. As a result of measuring the thermal resistance of the entire semiconductor device during the operation of the semiconductor element 12, it was 1.5 ° C./W, which is more than three times the above example. As a result of a trial calculation of the equivalent thermal conductivity of the entire semiconductor device 10A, it was 43 (arbitrary unit), which was 30% lower than that of the above example.

The result similar to this comparative example was obtained not in the build-up process but in the case of the semiconductor device sealed with the resin layer 20 (sealing resin) after forming the via on the first heat transfer layer 15. .
According to the semiconductor device using the second heat transfer layer as described above, it is possible to achieve low thermal resistance and high thermal conductivity, and it is possible to improve reliability and yield.

Regarding the embodiment described above, the following additional notes are further disclosed.
(Appendix 1) Lead frame,
A semiconductor element mounted on the lead frame;
A first heat transfer layer provided in the semiconductor element;
A second heat transfer layer connected to the first heat transfer layer;
A third heat transfer layer connected to the second heat transfer layer;
A resin layer that seals the semiconductor element, the first heat transfer layer, and the second heat transfer layer, and the third heat transfer layer is exposed;
A semiconductor device comprising:

  (Supplementary Note 2) The first heat transfer layer and the second heat transfer layer are connected using a first adhesive layer, and the second heat transfer layer and the third heat transfer layer are a second adhesive layer. The semiconductor device according to appendix 1, wherein the semiconductor device is connected using

(Supplementary Note 3) The semiconductor device according to Supplementary Note 1 or 2, wherein the second heat transfer layer is connected to the lead frame.
(Supplementary note 4) The semiconductor device according to any one of supplementary notes 1 to 3, wherein the second heat transfer layer is a sheet-like heat transfer member having a bent portion.

(Supplementary note 5) The semiconductor device according to any one of supplementary notes 1 to 3, wherein the second heat transfer layer is a linear heat transfer member having a bent portion.
(Supplementary note 6) The semiconductor device according to any one of supplementary notes 1 to 3, wherein the second heat transfer layer is a porous heat transfer member.

(Appendix 7) The semiconductor device according to any one of appendices 1 to 6, wherein a plurality of the second heat transfer layers are provided between the first heat transfer layer and the third heat transfer layer. .
(Supplementary Note 8) The semiconductor element is electrically connected to the lead frame using a wire, and the resin layer seals the semiconductor element, the first heat transfer layer, the second heat transfer layer, and the wire. The semiconductor device according to any one of appendices 1 to 7, wherein the semiconductor device is stopped.

(Appendix 9) A step of providing a first heat transfer layer in a semiconductor element;
Mounting the semiconductor element on a lead frame;
Connecting a second heat transfer layer to the first heat transfer layer;
Connecting a third heat transfer layer to the second heat transfer layer;
Sealing the semiconductor element, the first heat transfer layer, and the second heat transfer layer, and forming a resin layer exposed by the third heat transfer layer;
A method for manufacturing a semiconductor device, comprising:

  (Supplementary Note 10) The second heat transfer layer is connected to the first heat transfer layer using the first adhesive layer, and the third heat transfer layer is connected to the second heat transfer layer using the second adhesive layer. The manufacturing method of a semiconductor device according to appendix 9, wherein:

1, 10A, 10Aa, 10B, 10Ba Semiconductor device 2, 11 Lead frame 3, 12 Semiconductor element 4, 15 First heat transfer layer 5, 16, 16a, 16b, 16c, 16d Second heat transfer layer 6, 17 Third Heat transfer layer 7, 20 Resin layer 11a, 11b, 11c Lead portion 12a Electrode pad 12b Transistor portion 13 Die bond material 14 Wire 14a Gate wire 14b Source wire 14c Drain wire 18 First adhesive layer 19 Second adhesive layer 21 Heat transfer member 22 Third adhesive layer 23 Fourth adhesive layer 24 Sacrificial layer 100 Via

Claims (5)

A lead frame;
A semiconductor element mounted on the lead frame;
A first heat transfer layer provided in the semiconductor element;
A second heat transfer layer connected to the first heat transfer layer;
A third heat transfer layer connected to the second heat transfer layer;
A resin layer that seals the semiconductor element, the first heat transfer layer, and the second heat transfer layer, and the third heat transfer layer is exposed;
A semiconductor device comprising:   The first heat transfer layer and the second heat transfer layer are connected using a first adhesive layer, and the second heat transfer layer and the third heat transfer layer are connected using a second adhesive layer. The semiconductor device according to claim 1, wherein the semiconductor device is formed.   The semiconductor device according to claim 1, wherein the second heat transfer layer is connected to the lead frame.   The semiconductor device according to claim 1, wherein the second heat transfer layer is a sheet-like heat transfer member having a bent portion. Providing a first heat transfer layer in the semiconductor element;
Mounting the semiconductor element on a lead frame;
Connecting a second heat transfer layer to the first heat transfer layer;
Connecting a third heat transfer layer to the second heat transfer layer;
Sealing the semiconductor element, the first heat transfer layer, and the second heat transfer layer, and forming a resin layer exposed by the third heat transfer layer;
A method for manufacturing a semiconductor device, comprising:

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