SEMICONDUCTOR DEVICE

An embodiment includes a first substrate, a second substrate, a first semiconductor element, a second semiconductor element and a third substrate. The third substrate is provided between the first substrate and the second substrate. The first semiconductor element is provided on the first substrate. The second semiconductor element is provided on the second substrate. The third substrate includes a first connection member and a second connection member that have thermal conductivity and penetrate through the third substrate. The first semiconductor element is thermally coupled to the first substrate and coupled through the first connection member to the second substrate. The second semiconductor element is thermally coupled to the second substrate and coupled through the second connection member to the first substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2023-142949, filed on Sep. 4, 2023; the entire contents of which are incorporated herein by reference.

FIELD

Embodiments relate to a semiconductor device.

BACKGROUND

There is a power module (semiconductor device) that is equipped with multiple heat generating components such as power semiconductor elements. In such a power module, the multiple heat-generating components may be distributed and disposed on two substrates to improve a heat radiation property.

Further improvement in the heat radiation property in the power module leads to an improvement in a mounting density of an apparatus or a device equipped with the power module.

DETAILED DESCRIPTION

A semiconductor device according to an embodiment includes: a first substrate including a first base material that includes a first face and a second face opposite to the first face, and has thermal conductivity; a second substrate including a second base material that includes a third face facing the first face and a fourth face opposite to the third face, and has thermal conductivity; a first semiconductor element provided on the first face side; a second semiconductor element provided on the third face side; and a third substrate that is provided between the first substrate and the second substrate, and includes a third base material including a fifth face facing the first face and a sixth face opposite to the fifth face. The third substrate includes a first connection member that penetrates from the fifth face to the sixth face and has thermal conductivity, and a second connection member that penetrates from the fifth face to the sixth face, is provided apart from the first connection member, and has thermal conductivity. The first semiconductor element is thermally coupled to the first substrate and the first connection member between the first substrate and the first connection member. The second semiconductor element is thermally coupled to the second substrate and the second connection member between the second substrate and the second connection member.

Hereinafter, respective embodiments of the invention will be described with reference to the accompanying drawings.

The drawings are schematic and conceptual, and a relationship between the thickness and width of respective portions, a size ratio between the portions, and the like are not necessarily the same as real values. Even when the same portion is shown, dimensions and ratios may be shown differently depending on the drawings.

In the specification and the drawings, the same reference numeral will be given to the same elements which are described already, and detailed description will be appropriately omitted.

FIG.1is a schematic side view illustrating a power module according to a first embodiment.

FIG.2is a schematic cross-sectional view illustrating the power module according to the first embodiment.

As shown inFIG.1andFIG.2, a power module1according to the embodiment includes a first substrate10, a second substrate20, a third substrate30, a first semiconductor element41, and a second semiconductor element42.

The first semiconductor element41is provided on the first substrate10. The second semiconductor element42is provided on the second substrate20. The third substrate30is provided between the first substrate10and the second substrate20. The power module1includes a casing80that accommodates the first substrate10, the second substrate20, the third substrate30, the first semiconductor element41, and the second semiconductor element42. The casing80is formed from an insulating material. The casing80is formed from, for example, an epoxy-based resin or the like. InFIG.1, the casing80is indicated by a two-dot chain line to illustrate a mutual relationship of the first substrate10, the second substrate20, the third substrate30, the first semiconductor element41, and the second semiconductor element42from a side surface.

The first substrate10includes a base material (first base material)11and a wiring layer (first wiring layer)12. The base material11is a plate-shaped member including a first face11aand a second face11b. The second face11bis a face opposite to the first face11a.

Hereinafter, a configuration and the like of the power module1will be described by using a three-dimensional coordinate system. The three-dimensional coordinate system is an XYZ coordinate system. It is assumed that the first face11aof the base material11is a plane, and an XY-plane is parallel to the first face11a. In an example inFIG.1, the first semiconductor element41and the second semiconductor element42are arranged in an X-direction. A Z axis is orthogonal to the XY-plane, a direction from the first face11ato the second face11bis set as a positive direction, and the opposite direction is set as a negative direction.

InFIG.2, lengths of some constituent elements in the Z-axis direction are exaggerated to clearly show mutual relationships of positions of the first substrate10, the second substrate20, the third substrate30, a first connection member33, a second connection member34, the first semiconductor element41, and the second semiconductor element42. In addition, each constituent element is shown as a single constituent member even though the constituent element is composed of multiple constituent members in order to avoid complication of illustration in the drawing. Hereinafter, a length in the Z-axis direction may be referred to as a thickness or a height.

The base material11has an insulating property at least on the first face11a. The base material11is formed from a material having high thermal conductivity. The base material11contains, for example, Al2O3, AlN, or the like. The base material11may contain a metal such as Cu and Al.

The wiring layer12is provided on the first face11a. The wiring layer12may include multiple wirings. The multiple wirings may be electrically connected to each other or electrically isolated from each other. In the specific example inFIG.2, the wiring layer12includes wirings12aand12b. The wiring12ais electrically connected to a fourth connection member52. The wiring12bis electrically connected to the first semiconductor element41. In the example, the wiring12ais electrically isolated from the wiring12b.

The second substrate20includes a base material (second base material)21, and a wiring layer (second wiring layer)22. The base material21is a plate-shaped member including a third face21aand a fourth face21b. The fourth face21bis a face opposite to the third face21a. The first substrate10and the second substrate20are disposed so that from the first face11ato the fourth face21bare approximately parallel to each other. The second substrate20is disposed at a position where the third face21afaces the first face11a.

The base material21has an insulating property at least on the third face21a. The base material21is formed from a material having high thermal conductivity. The base material21contains, for example, Al2O3and AlN. The base material21may contain a metal such as Cu and Al. The base materials11and21may be formed from the same material or different materials.

The wiring layer22may include multiple wirings. The multiple wirings may be electrically connected to each other or electrically isolated from each other. In the example inFIG.2, the wiring layer22includes a wiring22a. The wiring22ais electrically connected to a third connection member51and the second semiconductor element42, respectively. Although not illustrated inFIG.2, the wiring layer22may include another wiring that is electrically isolated from, for example, the wiring22a.

The first semiconductor element41is electrically connected to the wiring layer12. The second semiconductor element42is electrically connected to the wiring layer22. For example, the first semiconductor element41and the second semiconductor element42are power semiconductor elements such as an insulated gate bipolar transistor (IGBT), a metal oxide semiconductor field effect transistor (MOSFET), a gate turn-off thyristor (GTO), and a diode. The power semiconductor element contains Si, SiC, GaN, or the like. The first semiconductor element41and the second semiconductor element42may be the same type of power semiconductor elements or may be different type of power semiconductor elements.

The first semiconductor element41is provided between the first substrate10and the third substrate30, and the second semiconductor element42is provided between the third substrate30and the second substrate20. The first semiconductor element41and the second semiconductor element42are disposed apart from each other in an X-axis direction.

The third substrate30includes a base material31, the first connection member33, and the second connection member34. The base material31is a plate-shaped member including a fifth face31aand a sixth face31b. The sixth face31bis a face located on a side opposite to the fifth face31a. The fifth face31aand the sixth face31bare disposed to be approximately parallel to the first face11a. The fifth face31afaces the first face11aand the sixth face31bfaces the third face21a.

The base material31is formed from a material having an insulating property. The base material31is formed from, for example, a glass epoxy substrate material such as FR-4, a glass composite substrate material such as CEM-3, or the like.

The first connection member33and the second connection member34are provided to penetrate from the fifth face31ato the sixth face31b.

The first connection member33includes a mounting face33S1and a heat radiation face3352. The mounting face33S1is exposed from the base material31on the fifth face31aside. The heat radiation face33S2is exposed from the base material31on the sixth face31bside.

The second connection member34includes a mounting face34S1and a heat radiation face34S2. The mounting face34S1is exposed from the base material31on the sixth face31bside. The heat radiation face34S2is exposed from the base material31on the fifth face31aside.

In a specific example inFIG.2, the third connection member51is provided between the heat radiation face33S2and the wiring layer22. The third connection member51thermally couples the first connection member33and the wiring layer22. The third connection member51has a function as a spacer that adjusts a length between the third substrate30and the second substrate20in the Z-axis direction. For example, the thickness of the third connection member51is equal to the thickness of the second semiconductor element42.

The fourth connection member52is provided between the heat radiation face3452and the wiring layer12. The fourth connection member52thermally couples the second connection member34and the wiring layer12. The fourth connection member52has a function as a spacer that adjusts a length between the third substrate30and the first substrate10in the Z-axis direction. For example, the thickness of the fourth connection member52is equal to the thickness of the first semiconductor element41.

The first semiconductor element41is provided between the first substrate10and the first connection member33. The first semiconductor element41is thermally coupled to the first substrate10. In addition, the first semiconductor element41is thermally coupled to the first connection member33on the mounting face33S1. The first connection member33is thermally coupled to the second substrate20on the heat radiation face33S2through the third connection member51.

Heat generated by the first semiconductor element41is radiated by the first substrate10. In addition, heat generated by the first semiconductor element41is conducted to the second substrate20through the first connection member33and the third connection member51, and is radiated by the second substrate20.

The second semiconductor element42is provided between the second connection member34and the second substrate20. The second semiconductor element42is thermally coupled to the second substrate20. In addition, the second semiconductor element42is thermally coupled to the second connection member34on the mounting face34S1. The second connection member34is thermally coupled to the first substrate10on the heat radiation face3452through the fourth connection member52.

Heat generated by the second semiconductor element42is radiated by the second substrate20. In addition, heat generated by the second semiconductor element42is conducted to the first substrate10through the second connection member34and the fourth connection member52, and is radiated by the first substrate10.

The first connection member33, the second connection member34, the third connection member51, and the fourth connection member52are formed from a material having high thermal conductivity. Thermal conductivity of the first connection member33, the second connection member34, the third connection member51, and the fourth connection member52is sufficiently higher than thermal conductivity of the base material31.

In the heat generated by the first semiconductor element41, the majority of heat that is conducted through the first connection member33and the third connection member51is conducted to the second substrate20side. In the heat generated by the second semiconductor element42, the majority of heat that is conducted through the second connection member34and the fourth connection member52is conducted to the first substrate10side. Since the first semiconductor element41and the second semiconductor element42are disposed apart from each other in an X-axis direction, the heat generation of the first semiconductor element41and the heat generation of the second semiconductor element42are radiated after being conducted through different routes. Therefore, in the power module1, a high heat radiation property is realized.

As shown inFIG.2, a first heat sink110can be provided on the second face11b. The first substrate10is thermally coupled to the first heat sink110. Favorably, a second heat sink120is also provided on the fourth face21b. The first heat sink110and the second heat sink120have thermal resistance sufficiently lower than that of the first base material11and the second base material21. Therefore, heat generated by the first semiconductor element41is more efficiently radiated by the first heat sink110and the second heat sink120. Heat generated by the second semiconductor element42is more efficiently radiated by the first heat sink110and the second heat sink120.

The first heat sink110and the second heat sink120may be an air-cooling heat sink or a water-cooling heat sink. In a case of providing the air-cooling heat sink, only one of the heat sinks may be provided, or both the heat sinks may be provided in correspondence with convection or the like due to arrangement of the power module1.

Circuit components61and62are provided on the third substrate30. In the example inFIG.1andFIG.2, the circuit component61is provided on the fifth face31aside, and the circuit component62is provided on the sixth face31bside. The circuit components61and62are, for example, passive components such as a capacitor and a resistive element, functional modules including an integrated circuit and various sensors, or the like, and an input/output current is smaller and an amplitude of an input/output voltage is lower as compared with the first semiconductor element41and the second semiconductor element42. In addition, heat generation of the circuit components61and62is smaller than heat generation of the first semiconductor element41and the second semiconductor element42. For example, the circuit components61and62are circuit elements that drive the first semiconductor element41and the second semiconductor element42, or that control a circuit that drives the first semiconductor element41and the second semiconductor element42.

The third substrate30includes a conductive layer36provided in an inner layer of the base material31. The conductive layer36is provided between the fifth face31aand the sixth face31b. In the specific example, the conductive layer36is electrically isolated from the first connection member33and the second connection member34. The conductive layer36is also provided between the circuit component61and the circuit component62. For example, a ground potential is applied to the conductive layer36. For example, the conductive layer36functions as a shielding layer against electromagnetic radiation caused by a switching operation of the first semiconductor element41and the second semiconductor element42, or the like.

Since the circuit components61and62are provided on the conductive layer36functioning as the shielding layer, malfunction due to the electromagnetic radiation or the like can be suppressed.

The third substrate30includes a wiring layer (third wiring layer)32a. The wiring layer32ais provided on the fifth face31aside. The wiring layer32acan include multiple wirings32a1,32a2, and32a3. The multiple wirings32a1,32a2, and32a3may be electrically connected to each other or electrically isolated from each other.

In the wiring layer32a, the thicknesses of the wirings32a1,32a2, and32a3can be made different from each other. The thickness of the wirings32a1and32a3is large. The thickness of the wiring32a2is smaller than the thickness of the wirings32a1and32a3. The wiring32a1having a large thickness is electrically connected to, for example, a main electrode of the first semiconductor element41. The main electrode is, for example, an emitter electrode of the IGBT. The wiring32a1can be used as a lead wire for connecting the emitter electrode of the first semiconductor element41to an external circuit. As to be described later with reference toFIG.4, in a case where the power module1is configured as a half-bridge circuit101, when the wiring32a1is set as a lead wire, the wiring32a1can also be set as a terminal for taking out a neutral point potential (AC output voltage) VAC.

The wiring32a3having a large thickness is electrically connected to the wiring12bthrough a fifth connection member53. The fifth connection member53is disposed between the wiring32a3and the wiring12bon a positive side of the first semiconductor element41in a Y-direction, and electrically connects the wiring32a3and the wiring12b. The thickness of the fifth connection member53is equal to the thickness of the first semiconductor element41and the thickness of the fourth connection member52, and also functions as a spacer. As in the specific example inFIG.2, the wiring32a3may be drawn out as a lead wire for connection with an external circuit. In this case, the wiring32a3can also be used as a terminal for connection of a DC power source V+of the half-bridge circuit101to be described later with reference toFIG.4.

As described above, when the thickness of the wirings32a1and32a3is made large, a large current can be allowed to flow through the wirings32a1and32a3.

For example, the wiring32a2having a small thickness electrically connects a control electrode of the first semiconductor element41and the circuit component61. The control electrode is, for example, a gate electrode of the IGBT. A current that is sufficiently smaller than the current flowing through the wirings32a1and32a3can be allowed to flow through the wiring32a2.

The third substrate30includes a wiring layer (fourth wiring layer)32b. The wiring layer32bis provided on the sixth face31bside. The wiring layer32bcan include multiple wirings32b1and32b2. The multiple wirings32b1and32b2may be electrically connected to each other or electrically isolated from each other.

In the wiring layer32b, the thicknesses of the wirings32b1and32b2may be made different from each other. The thickness of the wiring32b1is large. The thickness of the wiring32b2is smaller than the thickness of the wiring32b1.

For example, the wiring32b1having a large thickness is electrically connected to, for example, a main electrode of the second semiconductor element42. The main electrode is, for example, an emitter electrode of the IGBT. A large current can be allowed to flow through the wiring32b1. As in the specific example inFIG.2, the wiring32b1can also be used as a lead wire for connection with an external circuit. In a case where the power module1is configured as the half-bridge circuit101as to be described later with reference toFIG.4, the wiring32b1can also be used as a terminal for connection of a DC voltage source V−.

For example, the wiring32b2having a small thickness is electrically connected to a control electrode of the second semiconductor element42. The control electrode is, for example, a gate electrode of the IGBT. A current sufficiently smaller than a current flowing through the wiring32b1can be allowed to be flow through the wiring32b2.

When the wiring layers32aand32binclude wirings having different thicknesses, a wiring having a large thickness is applicable to a route through which a large current flows, and a wiring having a small thickness is applicable to a route through which a small current flows. In a case where the wiring having a large thickness is applied to the route through which the large current flows, it is not necessary to increase the length of the wiring in the X-direction and the Y-direction. In a case where the wiring having a small thickness is applied to the route through which the small current flows, it is easy to set a wiring interval to be narrow. According to these, it is possible to improve an arrangement density of circuit elements arranged on the third substrate30.

Favorably, the first connection member33, the second connection member34, the third connection member51, and the fourth connection member52are formed from an electrically conductive material. The first connection member33, the second connection member34, the third connection member51, and the fourth connection member52are formed from, for example, a metal material such as Cu, Al, an alloy containing these metals, or the like.

According to this, as to be described later with reference toFIG.4, in the third substrate30, the first connection member33can electrically connect the first semiconductor element41to the wiring layer22of the second substrate20, and the second connection member34can electrically connect the second semiconductor element42to the wiring layer12of the first substrate10. In addition, the first connection member33and the second connection member34can also be electrically connected to the wiring layers32aand32b, and the conductive layer36provided on the third substrate30.

FIG.3AtoFIG.3Care schematic perspective views illustrating the first connection member that is a part of the power module according to the embodiment.

As shown inFIG.3A, the first connection member33can be set to a circular column shape. In the first connection member33, the mounting face33S1and the heat radiation face33S2have a circular shape in XY-plan view. It is favorable that an area of the mounting face3351and the heat radiation face33S2is sufficiently large. For example, when the area of the mounting face33S1and the heat radiation face33S2is set to be approximately equal to or larger than an area of a main electrode to be connected to the mounting face33S1of the first semiconductor element41in the XY-plan view, thermal resistance due to connection between the first semiconductor element41and the first connection member33can be reduced, and the heat radiation property of the first semiconductor element41can be improved.

The first connection member33is not limited to the circular column shape, and may be set to, for example, an elliptical column shape in correspondence with an outer peripheral shape of the first semiconductor element41in the XY-plan view.

As shown inFIG.3B, a first connection member33amay be set to a square column shape. In the first connection member33a, a mounting face33aS1and a heat radiation face33aS2have a rectangular shape. When the area of the mounting face33aS1and the heat radiation face33aS2is set to be approximately equal to or larger than an area of the main electrode to be connected to the mounting face33S1of the first semiconductor element41in the XY-plan view, thermal resistance due to connection between the first semiconductor element41and the first connection member33acan be reduced, and the heat radiation property of the first semiconductor element41can be improved.

In addition, the shape of the outer periphery of the mounting face33aS1and the heat radiation face33aS2may be set so that the outer periphery of the mounting face33aS1and the heat radiation face33aS2overlaps the outer periphery of the main electrode of the first semiconductor element41to be connected to the mounting face33S1in the XY-plan view, or is positioned on an outer side of the outer periphery of the main electrode of the first semiconductor element41to be connected to the mounting face33S1in the XY-plan view. In this case, thermal coupling between the first semiconductor element41and the first connection member33acan be strengthened, and the heat radiation property of the first semiconductor element41can be further improved.

In addition, when the shape of the mounting face33aS1and the heat radiation face33aS2is set to the rectangular shape, an arrangement density of respective wirings of the wiring layers32aand32bcan be improved.

As shown inFIG.3C, a first connection member33bmay be set to a truncated square pyramid shape. A mounting face33bS1and a heat radiation face33bS2have a rectangular shape. In the specific example, an area of the heat radiation face33bS2is larger than an area of the mounting face33bS1. In this case, it is possible to realize a sufficiently high heat radiation property by reducing thermal resistance on the second substrate20side while improving a wiring density in the third substrate30.

The first connection member33bmay be set to, for example, a truncated cone, a truncated elliptical cone, or the like without limitation to the truncated square pyramid in correspondence with the outer peripheral shape of the first semiconductor element41in the XY-plan view.

In the above description, the shape of the first connection member33has been described, but the shape of the second connection member34can be set in a similar manner. In addition, the shape of the first connection members33,33a, and33bis illustrative only, and an appropriate shape can be set in any manner in correspondence with arrangement of respective wirings of the wiring layers on the third substrate30, the size of a semiconductor element, the shape of an electrode, and the like.FIG.4is a schematic equivalent circuit diagram of the power model according to the embodiment.

In each of the wiring layer12formed on the first substrate10, and the wiring layers12and22formed on the second substrate20, it is possible to construct a power module having a desired circuit configuration by approximately connecting the wirings.

Circuit elements inFIG.4correspond to constituent elements shown inFIG.1andFIG.2(hereinafter, referred to asFIG.1and the like). That is, a semiconductor element141and a semiconductor element142respectively correspond to the first semiconductor element41and the second semiconductor element42inFIG.1and the like. Connection members133and151, and a wiring122arespectively correspond to the first connection member33, the third connection member51, and the wiring22ainFIG.1and the like. A wiring132b1corresponds to the wiring32b1inFIG.1and the like. A connection member153and a wiring132a3correspond to the fifth connection member53and the wiring32a3inFIG.1and the like. A wiring132a1corresponds to the wiring32a1inFIG.1and the like.

As shown inFIG.4, for example, the power module1shown inFIG.1and the like can include the half-bridge circuit101. The half-bridge circuit101is a series circuit of the semiconductor elements141and142. Each of the semiconductor elements141and142is, for example, an insulated gate bipolar transistor (IGBT). Each of the semiconductor elements141and142includes a diode that is connected to the IGBT in reverse parallel.

The semiconductor element141includes a collector electrode C1, an emitter electrode E1, and a gate electrode G1. The collector electrode C1is electrically connected to a DC voltage source V+through the connection member153and the wiring132a3. The emitter electrode E1is electrically connected to the connection member133on a mounting face133S1. The connection member133is electrically connected to the connection member151on a heat radiation face13352, and is electrically connected to the wiring122a. The emitter electrode E1is electrically connected to one end of the wiring132a1, and a neutral point potential VAC is output from the other end of the wiring132a1.

The semiconductor element142includes a collector electrode C2, an emitter electrode E2, and a gate electrode G2. The collector electrode C2is electrically connected to the wiring122a. The emitter electrode E2is electrically connected to a DC voltage source V-through the wiring132b1. A voltage value of the DC voltage source V+is higher than a voltage value of the DC voltage source V.

The connection members133and151and the wiring122ahave impedance Z1, impedance Z2, and impedance Z3, respectively. The wiring132b1has impedance Z4. The connection member153and the wiring132a3have impedance Z5and impedance Z6, respectively. The wiring132a1has impedance Z7. That is, impedance of the first connection member33, impedance of the third connection member51, and impedance of the wiring22acorrespond to the impedance Z1, the impedance Z2, and the impedance Z3, respectively. Impedance of the wiring32b1corresponds to the impedance Z4. Impedance of the fifth connection member53and impedance of the wiring32a3correspond to the impedance Z5and the impedance Z6, respectively. Impedance of the wiring32a1corresponds to the impedance Z7.

The area of the mounting face33S1and the heat radiation face33S2of the first connection member33can be set to be sufficiently large. The area of the third connection member51and the wiring22ain the XY-plan view can be set to be sufficiently large. The area of the wiring32b1in the XY-plan view can be set to be sufficiently large. The area of the fifth connection member53and the wiring32a3in the XY-plan view can be set to be sufficiently large. The area of the wiring32a1in the XY-plan view can be set to be sufficiently large.

The first connection member33, the third connection member51, the wiring22a, the wiring32b1, the fifth connection member53, the wiring32a3, and the wiring32a1can be formed from a metal material such as Cu. Therefore, when these are set to the above-described shape, a DC resistance value corresponding to each of the impedance Z1, the impedance Z2, the impedance Z3, the impedance Z4, the impedance Z5, the impedance Z6, and the impedance Z7can be sufficiently lowered.

In addition, a parasitic inductance value corresponding to each of the impedance Z1, the impedance Z2, the impedance Z3, the impedance Z4, the impedance Z5, the impedance Z6, and the impedance Z7can also be sufficiently small according to the above-described shape.

When the DC resistance value corresponding to each of the impedance Z1, the impedance Z2, the impedance Z3, the impedance Z4, the impedance Z5, the impedance Z6, and the impedance Z7is set to be sufficiently small, a loss occurred in the DC resistance can be reduced. In addition, since a voltage drop caused by the DC resistance can be suppressed, for example, it is possible to sufficiently secure the magnitude of a voltage that is applied to the control electrode of the semiconductor element.

Since the parasitic inductance value corresponding to each of the impedance Z1, the impedance Z2, the impedance Z3, the impedance Z4, the impedance Z5, the impedance Z6, and the impedance Z7is made sufficiently small, it is possible to suppress occurrence of a noise or a surge voltage associated with the high-speed switching operation of the semiconductor element.

FIG.5Ais a schematic side view illustrating the power module according to the embodiment.FIG.5Bis a schematic side view illustrating a power module according to a comparative example.

FIG.5Ashows a model201afor performing thermal simulation in the configuration of the power module1shown inFIG.1and the like.

In the model201ainFIG.5A, semiconductor elements241and242correspond to the first semiconductor element41and the second semiconductor element42shown inFIG.1and the like, respectively. A base material211and a wiring layer212correspond to the base material11and the wiring layer12shown inFIG.1and the like, respectively. A base material221and a wiring layer222correspond to the base material21and the wiring layer22shown inFIG.1and the like, respectively. Connection members233,234,251, and252correspond to the first connection member33, the second connection member34, the third connection member51, and the fourth connection member52shown inFIG.1and the like, respectively. Wiring layers232aand232bcorrespond to the wiring layers32aand32bshown inFIG.1and the like, respectively.

FIG.5Bshows a model201bin which the connection member234is excluded from the model201ainFIG.5A. In the models201aand201b, notation of a model element corresponding to the base material31of the third substrate30shown inFIG.1and the like is omitted to avoid complication of illustration in the drawing and to clearly show the configuration of the connection members233and234. In simulation using the models201aand201b, model elements corresponding to the material and the shape of the base material31are provided.

In the models201aand201b, model elements are set to an appropriate material and an appropriate shape, and a power loss of 1 W is applied to a model element of the semiconductor element241, and a heat transfer coefficient corresponding to forced cooling by water flow is applied to model elements of the base materials211and221.

Under the conditions, in the model201acorresponding to the power module1according to the embodiment, it is confirmed that thermal resistance of approximately 40% is reduced as compared with the model201bof the comparative example.

An effect of the power module1according to the embodiment will be described.

The power module1according to the embodiment includes the first substrate10, the second substrate20, the third substrate30, the first semiconductor element41, and the second semiconductor element42. The third substrate30is provided between the first semiconductor element41provided on the first substrate10, and the second semiconductor element42provided on the second substrate20. The third substrate includes the first connection member33and the second connection member34which penetrate through the base material31.

The first connection member33and the second connection member34have high thermal conductivity. In addition, the base material11of the first substrate10and the base material21of the second substrate20have high thermal conductivity.

The first connection member33is thermally coupled to the first semiconductor element41on the mounting face33S1, and is thermally coupled to the second substrate20on the heat radiation face3352through the third connection member51. Therefore, heat of the first semiconductor element41is radiated by the first substrate10, and is radiated by the second substrate20through the first connection member33and the third connection member51.

The second connection member34is thermally coupled to the second semiconductor element42on the mounting face34S1, and is thermally coupled to the first substrate10on the heat radiation face3452through the fourth connection member52. Therefore, heat of the second semiconductor element42is radiated by the second substrate20, and is radiated by the first substrate10through the second connection member34and the fourth connection member52.

That is, it is possible to radiate heat of the first semiconductor element41from both the first substrate10side and the second substrate20side by the first connection member33and the second connection member34provided to penetrate through the base material31of the third substrate30. Similarly, it is possible to radiate heat of the second semiconductor element42from both the first substrate10side and the second substrate20side. Therefore, the power module1according to the embodiment realizes high heat radiation performance.

In the first connection member33, the area of the mounting face33S1that is thermally coupled to the first semiconductor element41can be set to be sufficiently large, and can be set to be approximately the same as an area of a thermal coupling face of the first semiconductor element41with the mounting face33S1. Therefore, contact thermal resistance between the first semiconductor element41and the first connection member33can be reduced, and the heat radiation performance of the power module1can be improved.

In the second connection member34, similarly, the area of the mounting face34S1can be set to be sufficiently large, and can be set to be approximately the same as an area of a thermal coupling face of the second semiconductor element42with the mounting face34S1. Therefore, contact thermal resistance between the second semiconductor element42and the second connection member34can be reduced, and the heat radiation performance of the power module1can be improved.

As illustrated inFIG.3AtoFIG.3C, the shape of each of the first connection member33and the second connection member34can be appropriately set. According to this, the heat radiation performance of the power module1can be improved, and the degree of freedom of arrangement of circuit elements including the first semiconductor element41and the second semiconductor element42can be improved, or an arrangement density thereof can be improved.

For example, when the first connection member33and the second connection member34are formed from Cu, an ally containing Cu, or the like, the first connection member33and the second connection member34can realize high electrical conductivity while realizing high thermal conductivity. In the third substrate30, the first connection member33and the second connection member34can be used as wiring members with low impedance. When using the first connection member33and the second connection member34as the wiring members in the third substrate30, in a circuit element including the first semiconductor element41and the second semiconductor element42, the power module1can switch a high voltage and a large current with a low noise and at a high speed.

The base material31of the third substrate30includes the conductive layer36. The conductive layer36is provided in an inner layer of the base material31, and can be electrically isolated from the first connection member and the second connection member34. When connecting the conductive layer36to a specific potential, the conductive layer36can be used as an electron shielding layer. When the conductive layer36is provided in the third substrate30, it is easy to provide the circuit components61and62which handle low-level signals on the third substrate30.

In the third substrate30, at least one of the fifth face31aside and the sixth face31bside, the wiring layers32aand32bcan include wirings different in thickness. When the thickness of a wiring to which a low voltage is applied or through which a small current flows is made smaller than the thickness of a wiring to which a high voltage is applied or through which a large current flows, it is possible to form a minute wiring pattern. Therefore, a mounting density of circuit elements in the power module1can be improved.

In a case where the circuit configuration in the power module1is set as the half-bridge circuit101shown inFIG.4, the wirings32a1,32a3, and32b1can be used as a lead wire for connection with an external circuit. In this case, when the thickness of the wirings is set to be sufficiently large, and an area in the XY-plan view is set to be sufficiently large, electrical connection with an external circuit can be established at low resistance and low inductance.

In addition, when the wiring32b1is directly connected to the emitter electrode of the second semiconductor element42, a current is allowed to flow from the second semiconductor element42to the DC voltage source V-without through the second connection member34. According to this, the second connection member34is less susceptible to a copper loss and an iron loss due to a current in the switching operation of the second semiconductor element42. Therefore, since the second connection member34is less susceptible to heat generation due to the copper loss and the iron loss, a heat radiation effect of the second semiconductor element42can be enhanced.

In this manner, it is possible to realize a semiconductor device in which multiple heat generation components are mounted, and which has a high heat radiation property.