Patent Publication Number: US-2023135461-A1

Title: Semiconductor device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to a semiconductor device. 
     2. Description of the Background Art 
     An electrically-driven vehicle such as an electric automobile or a plug-in hybrid automobile is provided with semiconductor devices for converting power from a high-voltage battery. Each semiconductor device is composed of a plurality of semiconductor elements such that a bridge circuit is formed. The semiconductor device converts, into AC power, DC power supplied from the battery in order to drive a motor. A semiconductor device including a circuit for converting DC power into AC power by appropriately operating semiconductor elements to be turned on or off, is called an inverter device. In such an inverter device, power transistors, IGBTs, FETs, and the like are widely used as the semiconductor elements serving as switching elements composing a bridge circuit. Further, inverter devices having a module structure in which a plurality of these semiconductor elements are mounted and made into one package, are widely used. 
     In the case of driving a motor of a motorized vehicle, high voltage is applied to and high current flows to the plurality of semiconductor elements in the module structure so that the semiconductor elements generate heat. The heat generation might cause fracture of the semiconductor elements. It is important to ascertain the temperature of each semiconductor element in order to protect the semiconductor element from fracture of the semiconductor element due to heat generation. 
     A configuration has been disclosed in which a temperature detection element is provided inside a semiconductor device in order to ascertain the temperature of a semiconductor element (see, for example, Patent Document 1). In the disclosed semiconductor device, the semiconductor element and the temperature detection element are apart from each other and mounted on an insulation layer. To each of a plurality of the semiconductor elements, a corresponding temperature detection element is provided at a position corresponding to the semiconductor element, and each of a plurality of the temperature detection elements detects the temperature of the corresponding semiconductor element.
     Patent Document 1: Japanese Laid-Open Patent Publication No. 2021-86933   

     In the structure of the semiconductor device in the above Patent Document 1, the temperature of each semiconductor element can be detected by the corresponding one of the plurality of temperature detection elements for protection from overheating. However, the semiconductor element and the temperature detection element are disposed on the insulation layer, and the semiconductor element and the temperature detection element are thermally connected to each other via the insulation layer. Thus, the thermal resistance between the semiconductor element and the temperature detection element is high, and a response by the temperature detection element might be delayed relative to increase in the temperature of the semiconductor element due to heat generation. Therefore, a drawback arises in that the temperature of the semiconductor element cannot be accurately detected. 
     In addition, the temperature detection elements are individually provided correspondingly to the plurality of semiconductor elements, and thus the number of control terminals and a space for wiring to the control terminals increase. Therefore, a drawback arises in that the semiconductor device is upsized. 
     SUMMARY OF THE INVENTION 
     Considering this, an object of the present disclosure is to provide a downsized semiconductor device in which the accuracy of detecting the temperature of a semiconductor element is improved. 
     A semiconductor device according to the present disclosure includes: a heat spreader formed in a plate shape; a plurality of semiconductor elements connected to a one-side surface of the heat spreader; and one or a plurality of temperature detection elements. Each temperature detection element is provided on the one-side surface of the heat spreader or inside any of the semiconductor elements. If a line segment connecting centers of two respective adjacent ones of the semiconductor elements is defined as X, a straight line that passes through one of the centers of the two adjacent semiconductor elements and that is perpendicular to X and parallel to the one-side surface of the heat spreader is defined as Y1, and a straight line that passes through another one of the centers of the two adjacent semiconductor elements and that is perpendicular to X and parallel to the one-side surface of the heat spreader is defined as Y2, at least a part of the temperature detection element is located in an arrangement region interposed between Y1 and Y2, as seen in a direction perpendicular to the one-side surface of the heat spreader. 
     In the semiconductor device according to the present disclosure: each temperature detection element is provided on the one-side surface of the heat spreader or inside any of the semiconductor elements; and, if a line segment connecting centers of two respective adjacent ones of the semiconductor elements is defined as X, a straight line that passes through one of the centers of the two adjacent semiconductor elements and that is perpendicular to X and parallel to the one-side surface of the heat spreader is defined as Y1, and a straight line that passes through another one of the centers of the two adjacent semiconductor elements and that is perpendicular to X and parallel to the one-side surface of the heat spreader is defined as Y2, at least a part of the temperature detection element is located in an arrangement region interposed between Y1 and Y2, as seen in a direction perpendicular to the one-side surface of the heat spreader. Consequently, the thermal resistances between the semiconductor elements and the temperature detection elements are low, and it is possible to decrease a delay, in a response by each temperature detection element, that occurs relative to increase in the temperatures of the semiconductor elements due to heat generation. Therefore, the accuracy of detecting the temperature of each semiconductor element can be improved. In addition, one of the temperature detection elements can accurately detect the temperatures of at least two of the semiconductor elements, and thus the one temperature detection element enables the at least two semiconductor elements to be protected from overheating. Therefore, the number of the temperature detection elements can be decreased, whereby the semiconductor device can be downsized. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a diagram showing a circuit configuration of an inverter in which semiconductor devices according to a first embodiment are used; 
         FIG.  2    is a plan view schematically showing configurations of two of the semiconductor devices according to the first embodiment; 
         FIG.  3    is a cross-sectional view schematically showing the semiconductor devices, taken at a cross-sectional position A-A in  FIG.  2   ; 
         FIG.  4    is a cross-sectional view schematically showing a temperature detection element of one of the semiconductor devices according to the first embodiment; 
         FIG.  5    is a plan view showing a major part of the semiconductor device according to the first embodiment; 
         FIG.  6    is a plan view schematically showing a configuration of a semiconductor device according to a second embodiment; 
         FIG.  7    is a plan view schematically showing configurations of semiconductor devices according to a third embodiment; 
         FIG.  8    is a cross-sectional view schematically showing the semiconductor devices, taken at a cross-sectional position B-B in  FIG.  7   ; 
         FIG.  9    is a plan view showing a major part of a semiconductor device according to a fourth embodiment; and 
         FIG.  10    is a side view schematically showing configurations of semiconductor devices according to a fifth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED 
     Embodiments of the Invention 
     Hereinafter, semiconductor devices according to embodiments of the present disclosure will be described with reference to the drawings. Description will be given while the same or corresponding members and parts in the drawings are denoted by the same reference characters. 
     First Embodiment 
       FIG.  1    is a diagram showing a circuit configuration of a main circuit  100  of an inverter in which semiconductor devices  101  according to a first embodiment are used.  FIG.  2    is a plan view schematically showing configurations of semiconductor devices  101   a  and  101   b  for a U phase.  FIG.  3    is a cross-sectional view schematically showing the semiconductor devices  101   a  and  101   b , taken at a cross-sectional position A-A in  FIG.  2   .  FIG.  4    is a cross-sectional view schematically showing a temperature detection element  2 U of the semiconductor device  101   a .  FIG.  5    is a plan view showing a major part of the semiconductor device  101   a . In  FIG.  2   , sealing members  12  have been excluded, and the broken lines indicate the external shapes of the sealing members  12 . Each semiconductor device  101  is a device for converting power through switching operations of semiconductor elements  1 . 
     &lt;Main Circuit  100  of Inverter&gt; 
     The main circuit  100  of the inverter is connected to a battery on the left side of  FIG.  1    and connected to a driven motor as a load on the right side of  FIG.  1   . The main circuit  100  of the inverter converts DC power from the battery into AC power and outputs the AC power. The main circuit  100  of the inverter has six semiconductor devices  101 . The main circuit  100  of the inverter is formed by three phases, i.e., the U phase, a V phase, and a W phase. The semiconductor devices  101   a  and  101   b  are provided for the U phase, semiconductor devices  101   c  and  101   d  are provided for the V phase, and semiconductor devices  101   e  and  101   f  are provided for the W phase. Each phase is formed by an upper arm and a lower arm. The semiconductor devices  101   a ,  101   c , and  101   e  are upper arms, and the semiconductor devices  101   b ,  101   d , and  101   f  are lower arms. Each semiconductor device  101  includes a temperature detection element  2  (not shown in  FIG.  1   ). 
     &lt;Semiconductor Devices  101 &gt; 
     The structures of the semiconductor devices  101  are the same among the phases. Thus, the configurations of the semiconductor devices  101  will be described with reference to  FIG.  2    and  FIG.  3   , with the U phase being a representative. In  FIG.  2    and  FIG.  3   , electrodes of semiconductor elements  1  and temperature detection elements  2  are not shown in order to make it easy to understand the configurations. Each of the semiconductor devices  101   a  and  101   b  includes: a heat spreader  8 U,  8 L formed in a plate shape; a plurality of semiconductor elements  1  connected to a one-side surface of the heat spreader  8 U,  8 L; and one or a plurality of temperature detection elements  2 . In the present embodiment, each of the semiconductor devices  101   a  and  101   b  includes: two semiconductor elements  1 U,  1 L; and one temperature detection element  2 U,  2 L. The number of the semiconductor elements  1  and the number of the temperature detection elements  2  are not limited thereto, and three semiconductor elements  1  and two temperature detection elements  2  may be included. The temperature detection element  2 U,  2 L is provided on the one-side surface of the heat spreader  8 U,  8 L or inside either of the semiconductor elements  1 U,  1 L. In the present embodiment, the temperature detection element  2 U,  2 L is provided on the one-side surface of the heat spreader  8 U,  8 L. Each of the temperature detection elements  2 U and  2 L includes two electrodes (not shown) and is connected to outside. 
     The semiconductor device  101   a  serving as an upper arm includes a first lead frame  3 U and a second lead frame  4 U which are main circuit wires. The semiconductor device  101   b  serving as a lower arm includes a first lead frame  3 L and a second lead frame  4 L which are main circuit wires. The first lead frames  3 U and  3 L and the second lead frames  4 U and  4 L are terminals regarding input and output for the U phase. The first lead frame  3 U is electrically connected to a surface of each semiconductor element  1 U that is on an opposite side to the heat spreader  8 U side. The first lead frame  3 L is electrically connected to a surface of each semiconductor element  1 L that is on an opposite side to the heat spreader  8 L side. The second lead frame  4 U is electrically connected to the one-side surface of the heat spreader  8 U. The second lead frame  4 L is electrically connected to the one-side surface of the heat spreader  8 L. A portion of the second lead frame  4 U that is on an opposite side to a portion thereof connected to the heat spreader  8 U, is exposed to outside from a sealing member  12  and connected to a P side which is an input side of the main circuit  100  of the inverter. A portion of the first lead frame  3 L that is on an opposite side to a portion thereof connected to the semiconductor element  1 L, is exposed to outside from a sealing member  12  and connected to an N side which is an input side of the main circuit  100  of the inverter. A portion of the first lead frame  3 U that is on an opposite side to a portion thereof connected to the semiconductor element  1 U, is exposed to outside from the sealing member  12  and connected to the U phase of the driven motor. A portion of the second lead frame  4 L that is on an opposite side to a portion thereof connected to the heat spreader  8 L, is exposed to outside from the sealing member  12  and connected to the U phase of the driven motor. The portions of the first lead frame  3 U and the second lead frame  4 L that are exposed to outside from the sealing members  12 , are connected to each other. 
     The semiconductor device  101   a  serving as an upper arm includes a third lead frame  5 U which is a control terminal, and the semiconductor device  101   b  serving as a lower arm includes a third lead frame  5 L which is a control terminal. The third lead frame  5 U is a terminal extending in a direction away from the heat spreader  8 U in a state of being apart from the heat spreader  8 U. The third lead frame  5 U is electrically connected to one of the electrodes of the temperature detection element  2 U via a first electric conductor  14 U 1 . The third lead frame  5 L is a terminal extending in a direction away from the heat spreader  8 L in a state of being apart from the heat spreader  8 L. The third lead frame  5 L is electrically connected to one of the electrodes of the temperature detection element  2 L via a first electric conductor  14 L 1 . The other electrode of the temperature detection element  2 U is electrically connected via a second electric conductor  14 U 2  to a monitoring terminal  3 U 1  extending from the first lead frame  3 U. The other electrode of the temperature detection element  2 L is electrically connected via a second electric conductor  14 L 2  to a monitoring terminal  3 L 1  extending from the first lead frame  3 L. End portions of the third lead frames  5 U and  5 L and end portions of the monitoring terminals  3 U 1  and  3 L 1  are exposed to outside from the sealing members  12  and connected to a control circuit (not shown) of the inverter. Protection of the semiconductor elements  1 U and  1 L from overheating is performed on the basis of detected temperature information outputted to the control circuit. Each of the first lead frames  3 U and  3 L, the second lead frames  4 U and  4 L, and the third lead frames  5 U and  5 L is made of an electrically conductive metal such as copper or aluminum. 
     &lt;Components of Semiconductor Device  101 &gt; 
     The components of each semiconductor device  101  will be described. Each upper arm and the corresponding lower arm have the same configuration, and thus description based on the semiconductor device  101   a  will be given. The two semiconductor elements  1 U are connected in parallel. Each semiconductor element  1 U is connected to the heat spreader  8 U by means of a die-bonding material  6 . The semiconductor element  1 U is, for example, a metal oxide semiconductor field effect transistor (MOSFET), and the MOSFET has three types of electrodes, i.e., a gate electrode, a drain electrode, and a source electrode. An electrode of the MOSFET that is connected to the heat spreader  8 U by means of the die-bonding material  6  is the drain electrode. An electrode of the MOSFET that is connected to the first lead frame  3 U is the source electrode. The die-bonding material  6  is solder or Ag sinter. The semiconductor element  1 U is formed on a semiconductor substrate made of silicon (Si) or a wide-bandgap semiconductor such as silicon carbide (SiC), gallium nitride (GaN), gallium oxide (GaO), or diamond. It is noted that the semiconductor element  1  may be an insulated gate bipolar transistor (IGBT). If the semiconductor element  1  is an IGBT, the IGBT has three types of electrodes, i.e., a gate electrode, a collector electrode, and an emitter electrode. The collector electrode corresponds to the drain electrode of the MOSFET, and the emitter electrode corresponds to the source electrode of the MOSFET. 
     The heat spreader  8 U is an electrically conductive rectangular metal plate having excellent thermal conductivity and is made of, for example, copper. Copper is a material having excellent electrical conductivity and excellent thermal conductivity. The semiconductor element  1 U and the temperature detection element  2 U are provided on the one-side surface of the heat spreader  8 U, and an insulation sheet  9  is provided on an other-side surface of the heat spreader  8 U. 
     The temperature detection element  2 U is, for example, a thermistor. The thermistor is an element having a resistance value that varies according to change in the temperature thereof. As shown in  FIG.  4   , the temperature detection element  2 U includes: a temperature detection portion  2   a  which is an element body portion; two electrodes  2   b  provided to the temperature detection portion  2   a  so as to be located on the opposite side to the heat spreader  8 U side; and a sealing material  2   c  sealing the temperature detection portion  2   a  in a state where portions of the two electrodes  2   b  that are on the opposite side to the heat spreader  8 U side are exposed. The temperature detection portion  2   a  is thermally connected to the one-side surface of the heat spreader  8 U via at least the sealing material  2   c . This configuration makes it possible to thermally connect the temperature detection element  2 U onto the heat spreader  8 U easily. The semiconductor element  1 U and the temperature detection element  2 U are disposed on the heat spreader  8 U, and the semiconductor element  1 U and the temperature detection element  2 U are thermally connected to each other via the heat spreader  8 U. Thus, the thermal resistance between the semiconductor element  1 U and the temperature detection element  2 U is low, and it is possible to decrease a delay, in a response by the temperature detection element  2 U, that occurs relative to increase in the temperature of the semiconductor element  1 U due to heat generation. Since the delay in the response by the temperature detection element  2 U can be decreased, the accuracy of detecting the temperature of the semiconductor element  1 U can be improved. 
     Since the temperature detection portion  2   a  is sealed by the sealing material  2   c , insulation between the temperature detection portion  2   a  and the outside is ensured. Thus, the heat spreader  8 U and a joining portion  2   d  provided on an outer peripheral portion of the sealing material  2   c  can be joined together by means of a joining material  7 . The joining portion  2   d  is made of metal. The joining material  7  is, for example, solder or Ag sinter. In the case where the temperature detection portion  2   a  of the temperature detection element  2 U is not sealed, a joining material  7  having insulation properties is used. It is noted that the number of the electrodes  2   b  of the temperature detection element  2 U is not limited to two. The number of the electrodes  2   b  of the temperature detection element  2 U only has to be at least two, and the electrodes  2   b  may be provided at any location on the temperature detection portion  2   a . Further, the temperature detection element  2 U may be a diode. 
     One of the electrodes  2   b  of the temperature detection element  2 U is connected to the third lead frame  5 U via the first electric conductor  14 U 1 , and the other electrode  2   b  of the temperature detection element  2 U is connected to the monitoring terminal  3 U 1  via the second electric conductor  14 U 2 . The first and second electric conductors  14 U 1  and  14 U 2  are, for example, bonding wires. If bonding wires are used as wires, the degree of freedom in wiring is improved so that space saving can be attained. However, the temperature detection element  2 U is very small, and the electrodes  2   b  to which the bonding wires are connected are also small, and thus defective connection between each bonding wire and the corresponding electrode  2   b  might occur. Considering this, in order to ameliorate the defective connection, a region for the connection may be enlarged, and thin metal plates may be used, instead of the bonding wires, as wires. An arrangement region of the temperature detection element  2 U will be described later. 
     A metal plate  10  is thermally connected via the insulation sheet  9  to the other-side surface of the heat spreader  8 U. The metal plate  10  is made of, for example, copper or aluminum. The insulation sheet  9  is made of, for example, a ceramic resin material having insulation properties. 
     The heat spreader  8 U, the two semiconductor elements  1 U, the temperature detection element  2 U, the first lead frame  3 U, the second lead frame  4 U, the third lead frame  5 U, the insulation sheet  9 , and the metal plate  10  are sealed by the sealing member  12 . The portion of the first lead frame  3 U that is on the opposite side to the portion thereof connected to each semiconductor element  1 U, the portion of the second lead frame  4 U that is on the opposite side to the portion thereof connected to the heat spreader  8 U, the portion of the third lead frame  5 U that is on the opposite side to the portion thereof connected to the first electric conductor  14 U 1 , and a surface of the metal plate  10  that is on an opposite side to a surface thereof connected to the insulation sheet  9 , are exposed from the sealing member  12 . The sealing member  12  is made of, for example, mold resin. This configuration makes it possible to easily form a semiconductor device having a 2-in-1 or 6-in-1 structure. Further, the semiconductor device having the 2-in-1 or 6-in-1 structure can be downsized. 
     A configuration obtained through the sealing by the sealing member  12  is the configuration of the semiconductor device  101   a . The metal plate  10  and the inside of the semiconductor device  101   a  including the semiconductor element  1 U and the like, are insulated from each other by the insulation sheet  9 . Heat generated inside the semiconductor device  101   a  is dissipated from the surface of the metal plate  10  that is on the opposite side to the surface thereof connected to the insulation sheet  9 . In order to promote the heat dissipation and cool the inside of the semiconductor device  101   a , the semiconductor device  101   a  may be further provided with a cooler  13 . The cooler  13  is thermally connected to the metal plate  10  via a joining layer  11 . Since the cooler  13  is thermally connected to the metal plate  10 , the cooler  13  is thermally connected to the other-side surface of the heat spreader  8 U. Likewise, the cooler  13  is thermally connected to an other-side surface of the heat spreader  8 L. The joining layer  11  is made of, for example, solder. The cooler  13  includes cooling fins (not shown) on the inner surface thereof. The cooler  13  is formed as, for example, a die casting of a metal such as an aluminum alloy or a copper alloy. The cooler  13  has a flow path (not shown) through which a coolant flows from the heat spreader  8 U side to the heat spreader  8 L side. The direction of each arrow shown in  FIG.  3    is a coolant-flowing direction  15 . The coolant flows in an orientation in which the upper arm side is defined as an upstream side and the lower arm side is defined as a downstream side. The orientation in which the coolant flows is not limited thereto, and may be such that the upper arm side is defined as the downstream side and the lower arm side is defined as the upstream side. 
     &lt;Arrangement Region of Temperature Detection Element  2 U&gt; 
     An arrangement region of the temperature detection element  2 U which is a major part of the present disclosure will be described with reference to  FIG.  5   . Although an arrangement region of the temperature detection element  2 U will be described, the same applies also to the temperature detection element  2 L.  FIG.  5    is a plan view showing the two semiconductor elements  1 U, the one temperature detection element  2 U, and the heat spreader  8 U of the semiconductor device  101   a . In  FIG.  5   , the electrodes of each semiconductor element  1 U and the temperature detection element  2 U are not shown. A line segment connecting the centers of the two respective adjacent semiconductor elements  1 U is defined as X. A straight line that passes through one of the centers of the two adjacent semiconductor elements  1 U and that is perpendicular to X and parallel to the one-side surface of the heat spreader  8 U is defined as Y1. A straight line that passes through the other one of the centers of the two adjacent semiconductor elements  1 U and that is perpendicular to X and parallel to the one-side surface of the heat spreader  8 U is defined as Y2. At least a part of the temperature detection element  2 U is located in an arrangement region interposed between Y1 and Y2, as seen in a direction perpendicular to the one-side surface of the heat spreader  8 U. In  FIG.  5   , a region delimited by a broken line is the arrangement region. The number of the temperature detection elements  2 U is smaller than the number of the semiconductor elements  1 U. 
     Since at least a part of the temperature detection element  2 U is located in such an arrangement region, the one temperature detection element  2 U can accurately detect the temperatures of at least two semiconductor elements  1 U. Consequently, the one temperature detection element  2 U enables the at least two semiconductor elements  1 U to be protected from overheating. Therefore, the number of the temperature detection elements  2 U can be decreased. Since the number of the temperature detection elements  2 U can be decreased, the semiconductor device  101   a  can be downsized. Even if the number of the semiconductor elements  1 U composing the semiconductor device  101   a  is two or more, the number of the temperature detection elements  2 U can be made smaller than the number of the semiconductor elements, and thus the number of the control terminals for outputting detected information from the temperature detection elements  2 U to outside, and a space for wiring from each temperature detection element  2 U, can be decreased. Since the number of the control terminals and the space for the wiring are decreased, the semiconductor device  101   a  can be downsized. 
     In the arrangement region, a position at which the detection accuracy of the temperature detection element  2 U is highest is a position that is located at the midpoint of X and that is apart from the semiconductor elements  1 U by the same distance. This is because the position is at a shortest distance from each semiconductor element  1 U. However, there is variation in characteristics among the semiconductor elements  1 U, and thus there is variation also in heat generation among the semiconductor elements  1 U. Thus, the temperature detection element  2 U is mounted at a position also in consideration of the variation in characteristics among the semiconductor elements  1 U.  FIG.  5    shows an example in which the temperature detection element  2 U is disposed at a position at which the detection accuracy thereof is highest, in consideration of the variation in characteristics among the semiconductor elements  1 U and characteristics of the temperature detection element  2 U. 
     As described above, the semiconductor device  101   a  according to the first embodiment includes: the heat spreader  8 U formed in a plate shape; the two semiconductor elements  1 U connected to the one-side surface of the heat spreader  8 U; and the one temperature detection element  2 U. The temperature detection element  2 U is provided on the one-side surface of the heat spreader  8 U. If a line segment connecting the centers of the two respective adjacent semiconductor elements  1 U is defined as X, a straight line that passes through one of the centers of the two adjacent semiconductor elements  1 U and that is perpendicular to X and parallel to the one-side surface of the heat spreader  8 U is defined as Y1, and a straight line that passes through the other one of the centers of the two adjacent semiconductor elements  1 U and that is perpendicular to X and parallel to the one-side surface of the heat spreader  8 U is defined as Y2, at least a part of the temperature detection element  2 U is located in the arrangement region interposed between Y1 and Y2, as seen in the direction perpendicular to the one-side surface of the heat spreader. Consequently, since each semiconductor element  1 U and the temperature detection element  2 U are disposed on the heat spreader  8 U, and the semiconductor element  1 U and the temperature detection element  2 U are thermally connected to each other via the heat spreader  8 U, the thermal resistance between the semiconductor element  1 U and the temperature detection element  2 U is low, and it is possible to decrease a delay, in a response by the temperature detection element  2 U, that occurs relative to increase in the temperature of the semiconductor element  1 U due to heat generation. Therefore, the accuracy of detecting the temperature of the semiconductor element  1 U can be improved. In addition, the one temperature detection element  2 U can accurately detect the temperatures of at least two semiconductor elements  1 U, and thus the one temperature detection element  2 U enables the at least two semiconductor elements  1 U to be protected from overheating. Therefore, the number of the temperature detection elements  2 U can be decreased, whereby the semiconductor device  101   a  can be downsized. 
     If the number of the temperature detection elements  2 U is smaller than the number of the semiconductor elements  1 U, the number of the control terminals for outputting detected information from the temperature detection elements  2 U to outside, and the space for the wiring from each temperature detection element  2 U, can be decreased. Therefore, the semiconductor device  101   a  can be downsized. If the temperature detection element  2 U is provided on the one-side surface of the heat spreader  8 U, and the temperature detection portion  2   a  of the temperature detection element  2 U is thermally connected to the one-side surface of the heat spreader  8 U via at least the sealing material  2   c , the temperature detection element  2 U can be thermally connected onto the heat spreader  8 U easily. 
     If the heat spreader  8 U, the plurality of semiconductor elements  1 U, the temperature detection element  2 U, the first lead frame  3 U, the second lead frame  4 U, the third lead frame  5 U, the insulation sheet  9 , and the metal plate  10  are sealed by the sealing member  12 , a semiconductor device having a 2-in-1 or 6-in-1 structure can be easily formed. Further, the semiconductor device having the 2-in-1 or 6-in-1 structure can be downsized. 
     Second Embodiment 
     A semiconductor device  101   a  according to a second embodiment will be described.  FIG.  6    is a plan view schematically showing a configuration of the semiconductor device  101   a  according to the second embodiment, and is a diagram in which the sealing member  12  has been excluded. A broken line shown in  FIG.  6    indicates the external shape of the sealing member  12 . The semiconductor device  101   a  according to the second embodiment has a configuration in which a cut  8 U 1  is formed in the heat spreader  8 U. 
     The cut  8 U 1  is formed in the outer peripheral portion of the heat spreader  8 U. The cut  8 U 1  is a portion formed by cutting the heat spreader  8 U from the outer periphery thereof to the inside thereof. Although the cut  8 U 1  is formed in a rectangular shape in the present embodiment, the shape of the cut  8 U 1  is not limited thereto, and the cut  8 U 1  may be a portion delimited by a curved line. In the case of making the heat spreader  8 U through press working, the cut  8 U 1  can be simultaneously formed at the time of the press working. The cut  8 U 1  may be formed by, after the heat spreader  8 U is made, eliminating a part of the heat spreader  8 U through cutting or the like. 
     As seen in the direction perpendicular to the one-side surface of the heat spreader  8 U, a portion of the third lead frame  5 U that is on the heat spreader  8 U side overlaps with a region in which the cut  8 U 1  is formed. With this configuration, the third lead frame  5 U can be disposed inward of an outer periphery, of the heat spreader, that does not have any cut  8 U 1 . Thus, the semiconductor device  101   a  can be downsized in a direction in which the third lead frame  5 U extends. 
     As seen in the direction perpendicular to the one-side surface of the heat spreader  8 U, the two adjacent semiconductor elements  1 U are disposed apart from each other in regions on both sides between which the cut  8 U 1  is interposed, and the temperature detection element  2 U is disposed adjacently to the cut  8 U 1 . Heat generated from each semiconductor element  1 U is likely to concentrate at a region, of the heat spreader  8 U, that has been narrowed owing to cutting. If the temperature detection element  2 U is disposed in the region, of the heat spreader  8 U, that has been narrowed owing to the cutting in this manner, the responsiveness of the temperature detection element  2 U can be improved. Since the responsiveness of the temperature detection element  2 U is improved, the accuracy of detecting the temperature of the semiconductor element  1 U can be improved. 
     Third Embodiment 
     Semiconductor devices  101  according to a third embodiment will be described.  FIG.  7    is a plan view schematically showing configurations of semiconductor devices  101   a  and  101   b  according to the third embodiment.  FIG.  8    is a cross-sectional view schematically showing the semiconductor devices  101   a  and  101   b , taken at a cross-sectional position B-B in  FIG.  7   . In  FIG.  7   , a sealing member  12  has been excluded, and a broken line indicates the external shape of the sealing member  12 . In the semiconductor devices  101  according to the third embodiment, configurations of first lead frames  31 U and  31 L and a second lead frame  41 L which are main circuit wires, and a configuration of the sealing member  12 , are different from those in the first embodiment. 
     The configurations of the first lead frames  31 U and  31 L and second lead frames  41 U and  41 L will be described. The first lead frame  31 U has one end connected to each semiconductor element  1 U composing the semiconductor device  101   a  serving as an upper arm. Another end of the first lead frame  31 U is connected to the one-side surface of the heat spreader  8 L of the semiconductor device  101   b . The second lead frame  41 U has one end electrically connected to the one-side surface of the heat spreader  8 U. Another end of the second lead frame  41 U is connected to the P side which is an input side of the main circuit  100  of the inverter. The first lead frame  31 L has one end connected to each semiconductor element  1 L composing the semiconductor device  101   b  serving as a lower arm. Another end of the first lead frame  31 L is connected to the N side which is an input side of the main circuit  100  of the inverter. The second lead frame  41 L has one end electrically connected to the one-side surface of the heat spreader  8 L. Another end of the second lead frame  41 L is connected to the U phase of the driven motor. 
     As shown in  FIG.  8   , the first lead frame  31 U and the first lead frame  31 L are disposed apart from each other so as to overlap while being kept parallel to each other. Directions of currents that respectively flow in the first lead frame  31 U and the first lead frame  31 L, are opposite to each other. Thus, directions of magnetic fields generated owing to the currents are also opposite to each other, and the magnetic fields cancel each other. Therefore, an inductance can be decreased. 
     The configuration of the sealing member  12  will be described. In the present embodiment, the semiconductor devices  101   a  and  101   b  serving as the upper and lower arms for the U phase are sealed together by the sealing member  12 . Since the first lead frames  31 U and  31 L and the second lead frame  41 L have the above configurations, the semiconductor devices  101   a  and  101   b  can be sealed together by the sealing member  12 . Further, the heat spreaders  8 U and  8 L are thermally connected to one metal plate  10  without providing the metal plates  10  respectively to the heat spreaders  8 U and  8 L. 
     If the semiconductor devices  101   a  and  101   b  are sealed together by the sealing member  12 , the upper and lower arms can be more easily connected to each other than in the configuration described in the first embodiment in which each arm is separately sealed. In addition, the semiconductor devices  101   a  and  101   b  can be disposed close to each other. Thus, the lengths of the terminals to which the upper and lower arms are connected can be shortened, and the semiconductor devices  101   a  and  101   b  serving as the upper and lower arms can be downsized. 
     In general, the structure in which each arm for the U phase is separately sealed as in the first embodiment, is called a 1-in-1 structure, and the structure in which the upper and lower arms for the U phase are sealed together as in the third embodiment, is called a 2-in-1 structure. A 4-in-1 structure and a 6-in-1 structure can be easily constructed on the basis of the 2-in-1 structure described in the third embodiment. In the main circuit  100  of the inverter in the present disclosure, any of the structures may be used. By using the structure in which the arms for each phase are sealed together, the number of the terminals is decreased, whereby the inverter can be downsized. 
     Fourth Embodiment 
     A semiconductor device  101   a  according to a fourth embodiment will be described.  FIG.  9    is a plan view showing a major part of the semiconductor device  101   a  according to the fourth embodiment, and is a plan view showing the two semiconductor elements  1 U, the one temperature detection element  2 U, and the heat spreader  8 U of the semiconductor device  101   a . In  FIG.  9   , the electrodes of the semiconductor elements  1 U and the temperature detection element  2 U are not shown. The semiconductor device  101   a  according to the fourth embodiment has a configuration in which the temperature detection element  2 U is provided inside either of the semiconductor elements  1 U. 
     The temperature detection element  2 U is provided inside one or another one of the two adjacent semiconductor elements  1 U. In  FIG.  9   , the temperature detection element  2 U is provided inside the semiconductor element  1 U disposed on the right side. Since the temperature detection element  2 U is provided inside the semiconductor element  1 U, the external shape of the temperature detection element  2 U is indicated by a broken line. The temperature detection element  2 U is a diode. With this configuration, the semiconductor element  1 U and the temperature detection element  2 U are thermally connected to each other inside the semiconductor element  1 U. Thus, the thermal resistance between the semiconductor element  1 U and the temperature detection element  2 U is low, and it is possible to decrease a delay, in a response by the temperature detection element  2 U, that occurs relative to increase in the temperature of the semiconductor element  1 U due to heat generation. Since the delay in the response by the temperature detection element  2 U can be decreased, the accuracy of detecting the temperature of the semiconductor element  1 U can be improved. 
     In addition, the temperature detection element  2 U is connected to the source electrode inside the semiconductor element  1 U, and thus the number of wires of the temperature detection element  2 U is one, and the one wire is connected to the third lead frame  5 U. Since the number of the wires of the temperature detection element  2 U is one, the space for the wiring is decreased as compared to the case where the temperature detection element  2 U is provided outside of the semiconductor element  1 U. Thus, further space saving can be attained, whereby the semiconductor device  101   a  can be further downsized. 
     If the temperature detection element  2 U is provided inside the semiconductor element  1 U, the interval between the two adjacent semiconductor elements  1 U is desirably a shortest interval that enables insulation between both semiconductor elements  1 U to be ensured. If the two adjacent semiconductor elements  1 U are disposed such that the interval between the two adjacent semiconductor elements  1 U becomes shortest while the interval is kept as a distance that enables the insulation to be ensured, it is possible to protect both semiconductor elements  1 U from overheating while maintaining the accuracy of detecting the temperatures of both semiconductor elements  1 U, even in the case of embedding the temperature detection element  2 U in one of the semiconductor elements  1 U. 
     Fifth Embodiment 
     Semiconductor devices  101  according to a fifth embodiment will be described.  FIG.  10    is a side view schematically showing configurations of the semiconductor devices  101  according to the fifth embodiment. In  FIG.  10   , the sealing member  12  has been excluded, and the lead frames are not shown. The semiconductor devices  101  according to the fifth embodiment have a configuration in which the temperature detection element  2 U is not provided and only the temperature detection element  2 L is provided. The arrangement of the semiconductor elements  1  is the same as that in  FIG.  2    described in the first embodiment. 
     The semiconductor devices  101  are provided with the cooler  13 . The semiconductor devices  101  include two sets. Each set is composed of: the heat spreader; and the plurality of semiconductor elements connected to the one-side surface of the heat spreader. The two sets in the present embodiment are the semiconductor device  101   a  and the semiconductor device  101   b . The semiconductor device  101   a  is defined as a first set, and the semiconductor device  101   b  is defined as a second set. The cooler  13  is thermally connected to the other-side surfaces of the heat spreaders  8 U and  8 L of the respective sets. In the present embodiment, the heat spreaders  8 U and  8 L and the metal plate  10  are thermally connected to each other via the insulation sheet  9 , and the metal plate  10  and the cooler  13  are thermally connected to each other via the joining layer  11 . The cooler  13  has a flow path (not shown) through which the coolant flows from the heat spreader  8 U side in the first set to the heat spreader  8 L side in the second set. The direction of each arrow shown in  FIG.  10    is the coolant-flowing direction  15 . The coolant flows in an orientation in which the upper arm side is defined as an upstream side and the lower arm side is defined as a downstream side. 
     The temperature detection element  2  is provided at least on the one-side surface of the heat spreader  8 L of the second set or inside either of the semiconductor elements  1 L connected to the one-side surface of the heat spreader  8 L of the second set. In the present embodiment, the temperature detection element  2 L is provided on the one-side surface of the heat spreader  8 L of the second set. The temperature detection element  2 U is provided neither on the one-side surface of the heat spreader  8 U of the first set nor inside either of the semiconductor elements  1 U connected to the one-side surface of the heat spreader  8 U of the first set. 
     If the coolant flowing through the cooler  13  flows in an orientation in which the upper arm side is defined as the upstream side and the lower arm side is defined as the downstream side, the coolant is warmed by heat generated from the semiconductor device  101   a , and then the semiconductor device  101   b  is cooled by the warmed coolant. Thus, the semiconductor elements  1 L composing the semiconductor device  101   b  on the downstream side are more likely to have high temperatures than the semiconductor elements  1 U composing the semiconductor device  101   a  on the upstream side. Considering this, at least the temperature detection element  2 L is provided on the one-side surface of the heat spreader  8 L of the second set so that protection from overheating is performed on the semiconductor elements  1 L which are more likely to have high temperatures. Consequently, the semiconductor elements  1 U of the semiconductor device  101   a  on the upstream side can also be protected. In addition, if the temperature detection element  2 U is provided neither on the one-side surface of the heat spreader  8 U of the first set nor inside either of the semiconductor elements  1 U connected to the one-side surface of the heat spreader of the first set, the number of the temperature detection elements can be decreased. Thus, the number of the control terminals can be decreased, whereby the semiconductor devices can be downsized. 
     The arrangement of the temperature detection element  2 L will be further described. The temperature detection element  2 L provided on the one-side surface of the heat spreader  8 L of the second set or inside either of the semiconductor elements  1 L connected to the one-side surface of the heat spreader  8 L of the second set, is disposed in a region that is closer to the downstream side for the coolant than X in the arrangement region is. The temperature on the downstream side of the semiconductor elements  1 L composing the semiconductor device  101   b  on the downstream side is more likely to become high than the temperature on the upstream side of the semiconductor elements  1 L. This is because, on the downstream side of the semiconductor elements  1 L, the coolant has passed through the semiconductor elements  1 L having generated heat, so that the temperature of the coolant has increased. Considering this, the temperature detection element  2 L is provided in the region that is closer to the downstream side for the coolant than X in the arrangement region is, whereby protection from overheating is performed on the downstream side, of the semiconductor elements  1 L, on which the temperature is likely to become high. Consequently, the semiconductor elements  1 L can be assuredly protected from overheating. 
     As described above, in the semiconductor devices  101  according to the fifth embodiment, the cooler  13  has the flow path through which the coolant flows from the heat spreader  8 U side in the first set to the heat spreader  8 L side in the second set, and the temperature detection element  2  is provided at least on the one-side surface of the heat spreader  8 L of the second set or inside either of the semiconductor elements  1 L connected to the one-side surface of the heat spreader  8 L of the second set. Consequently, protection from overheating is performed on the semiconductor elements  1 L which are more likely to have high temperatures. Thus, the semiconductor elements  1 U of the semiconductor device  101   a  on the upstream side can also be protected. 
     If the temperature detection element  2 U is provided neither on the one-side surface of the heat spreader  8 U of the first set nor inside either of the semiconductor elements  1 U connected to the one-side surface of the heat spreader of the first set, the number of the temperature detection elements can be decreased. Thus, the number of the control terminals can be decreased, whereby the semiconductor devices can be downsized. In addition, the temperature on the downstream side of the semiconductor elements  1 L composing the semiconductor device  101   b  on the downstream side is more likely to become high than the temperature on the upstream side of the semiconductor elements  1 L. Thus, if the temperature detection element  2 L is disposed in the region that is closer to the downstream side for the coolant than X in the arrangement region is, protection from overheating is performed on the downstream side, of the semiconductor elements  1 L, on which the temperature is likely to become high. Consequently, the semiconductor elements  1 L can be assuredly protected from overheating. 
     Although the disclosure is described above in terms of various exemplary embodiments and implementations, it should be understood that the various features, aspects, and functionality described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead can be applied, alone or in various combinations to one or more of the embodiments of the disclosure. 
     It is therefore understood that numerous modifications which have not been exemplified can be devised without departing from the scope of the specification of the present disclosure. For example, at least one of the constituent components may be modified, added, or eliminated. At least one of the constituent components mentioned in at least one of the preferred embodiments may be selected and combined with the constituent components mentioned in another preferred embodiment. 
     DESCRIPTION OF THE REFERENCE CHARACTERS 
     
         
         
           
               1 ,  1 U,  1 L semiconductor element 
               2 ,  2 U,  2 L temperature detection element 
               2   a  temperature detection portion 
               2   b  electrode 
               2   c  sealing material 
               2   d  joining portion 
               3 U,  3 L,  31 U,  31 L first lead frame 
               3 U 1  monitoring terminal 
               3 L 1  monitoring terminal 
               4 U,  4 L,  41 U,  41 L second lead frame 
               5 U,  5 L third lead frame 
               6  die-bonding material 
               7  joining material 
               8 U,  8 L heat spreader 
               8 U 1  cut 
               9  insulation sheet 
               10  metal plate 
               11  joining layer 
               12  sealing member 
               13  cooler 
               14 U 1  first electric conductor 
               14 U 2  second electric conductor 
               14 L 1  first electric conductor 
               14 L 2  second electric conductor 
               15  coolant-flowing direction 
               100  main circuit of inverter 
               101  semiconductor device