Patent Publication Number: US-2023155012-A1

Title: Semiconductor device

Description:
TECHNICAL FIELD 
     The present disclosure relates to a semiconductor device including a semiconductor chip having a switching element in the inside. 
     BACKGROUND ART 
     As a semiconductor device for electric power, a semiconductor device including a semiconductor chip having a switching element such as an insulated gate bipolar transistor (IGBT) or a metal-oxide-semiconductor field effect transistor (MOSFET) in the inside is generally used. 
     Examples of a conventional power semiconductor device include a semiconductor device disclosed in Patent Document 1. 
     PRIOR ART DOCUMENT 
     Patent Document 
     
         
         Patent Document 1: Japanese Patent Application Laid-Open No. 2013-45996 
       
    
     SUMMARY 
     Problem to be Solved by the Invention 
     In a conventional power semiconductor device, an IGBT has been used as a switching element, and potential obtained from an outer peripheral region of an emitter electrode has been used as emitter potential serving as reference potential of gate voltage serving as control voltage for operating and controlling the IGBT in an IGBT chip. 
     On the other hand, a wiring connection region provided in a central portion of an emitter electrode is generally electrically connected to an external terminal, and current flowing through a wiring connection region is main current. 
     Ideally, potential in an emitter electrode surface is constant, but since an emitter electrode has a minute resistance component, when current flows through an IGBT, distribution occurs in potential in a plane of the emitter electrode. 
     Therefore, in the conventional semiconductor device, main current tends to increase according to potential distribution in a plane of an emitter electrode. In particular, when large current flows due to short circuit or the like as main current, the above-described tendency becomes remarkable, and thus there has been a problem that an IGBT chip may be thermally broken due to increase in main current of an IGBT. 
     The present disclosure has been made to solve the above problem, and an object of the present disclosure is to provide a highly reliable semiconductor device. 
     Means to Solve the Problem 
     A first aspect of a semiconductor device according to the present disclosure provides a semiconductor chip having a switching element therein, and a surface electrode provided on a surface of the semiconductor chip and through which main current flows during operation of the switching element, in which the switching element has a control electrode, and the switching element is operated and controlled by applying a control voltage with potential of the surface electrode as reference potential to the control electrode, the semiconductor device further including an insulating film provided on the surface electrode, in which the insulating film has an opening region, and a region in the opening region in the surface electrode serves as a wiring connection region, the semiconductor device further including a chip bonding material that has a lower surface and is electrically connected to the surface electrode by contacting the lower surface with a surface of the wiring connection region, a sense pad provided in a manner being in contact with the surface electrode on a surface of the semiconductor chip, and a sense wiring provided on a surface of the semiconductor chip and electrically connecting the surface electrode and the sense pad, in which potential of the sense pad is control reference potential of the switching element, the lower surface of the chip bonding material has a shape matching a surface shape of the wiring connection region in plan view, the sense wiring is connected to the wiring connection region, and the semiconductor chip has an ineffective region in which the switching element does not function in a region below the sense pad and the sense wiring. 
     A second aspect of the semiconductor device according to the present disclosure provides a semiconductor chip having a switching element therein, and a surface electrode provided on a surface of the semiconductor chip and through which main current flows during operation of the switching element, in which the switching element has a control electrode, and the switching element is operated and controlled by applying a control voltage with potential of the surface electrode as reference potential to the control electrode, a chip wire that is electrically connected to the surface electrode by contacting at a chip connection point on a surface of the surface electrode, and a sense connection member that is electrically connected to the surface electrode by contacting at a sense connection point of the surface electrode, potential of the sense connection point is control reference potential of the switching element, a region including the chip connection point in the surface electrode is defined as a wiring connection region, and a position farthest from the wiring connection region in the surface electrode is defined as an electrode remote position, and the sense connection point satisfies a connection point arrangement condition that a connection point is provided at a position close to the chip connection point between the chip connection point and the electrode remote position. 
     Effects of the Invention 
     The first aspect of the semiconductor device of the present disclosure has features (1) to (3) below.
         (1) The lower surface of the chip bonding material has a shape matching a surface shape of the wiring connection region in plan view.   (2) The sense wiring is connected to the wiring connection region.   (3) The semiconductor chip has an ineffective region in which the switching element does not function in a region below the sense pad and the sense wiring.       

     Since the first aspect of the semiconductor device of the present disclosure has the above-described features (1) to (3), control reference potential during operation of the switching element is not affected by a resistance component based on a distance from the wiring connection region. 
     On the other hand, in the surface electrode of the first aspect, remote region reference potential, which is potential in a surface electrode remote region relatively away from the wiring connection region, is affected by a resistance component based on a distance from the wiring connection region, and has a reference potential fluctuation characteristic in which potential fluctuates from the control reference potential. 
     Therefore, according to the first aspect of the semiconductor device of the present disclosure, when large current flows as main current of the surface electrode at the time of a short circuit or the like, an amount of current flowing in the surface electrode remote region can be reduced according to the reference potential fluctuation characteristic. 
     As a result, according to the fast aspect of the semiconductor device of the present disclosure, increase in an amount of the main current can be effectively suppressed by reducing an amount of current flowing through the surface electrode remote region, and reliability of the device can be improved. 
     The second aspect of the semiconductor device of the present disclosure has a feature (4) below.
         (4) The sense connection point satisfies the connection point arrangement condition that the connection point is provided at a position close to the chip connection point between the chip connection point and the electrode remote position.       

     The second aspect of the semiconductor device of the present disclosure has the above feature (4), and by arranging the sense connection point close to the chip connection point, the control reference potential during operation of the switching element is hardly affected by a resistance component based on a distance from the wiring connection region. 
     On the other hand, in the surface electrode of the second aspect, the remote region reference potential, which is a potential in the surface electrode remote region relatively away from the wiring connection region, has a reference potential fluctuation characteristic in which potential fluctuates from the control reference potential under the influence of the resistance component based on the distance from the wiring connection region. 
     Therefore, according to the second aspect of the semiconductor device of the present disclosure, when large current flows as main current of the surface electrode at the time of a short circuit or the like, an amount of current flowing in the surface electrode remote region can be reduced according to the reference potential fluctuation characteristic. 
     As a result, according to the second aspect of the semiconductor device of the present disclosure, increase in an amount of the main current can be effectively suppressed by reducing an amount of current flowing through the surface electrode remote region, and reliability of the device can be improved. 
     An object, a feature, an aspect, and an advantage of the present disclosure will become clearer from detailed description below and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is an explanatory diagram illustrating a structure of a semiconductor device according to a first embodiment. 
         FIG.  2    is an explanatory diagram illustrating a structure of the semiconductor device of the first embodiment. 
         FIG.  3    is a circuit diagram showing an equivalent circuit of the semiconductor device of the first embodiment. 
         FIG.  4    is an explanatory diagram illustrating a structure of the semiconductor device according to a second embodiment. 
         FIG.  5    is an explanatory diagram illustrating a structure of the semiconductor device according to a third embodiment. 
         FIG.  6    is an explanatory diagram illustrating a structure of the semiconductor device according to a fourth embodiment. 
         FIG.  7    is an explanatory diagram illustrating a structure of the semiconductor device according to a fourth embodiment. 
         FIG.  8    is a circuit diagram illustrating the equivalent circuit of the fourth embodiment. 
         FIG.  9    is an explanatory diagram illustrating a structure of a semiconductor device as a basic technique. 
         FIG.  10    is a circuit diagram illustrating the equivalent circuit of the semiconductor device illustrated in  FIG.  9   . 
         FIG.  11    is a circuit diagram illustrating an equivalent circuit of a semiconductor device for comparison. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     &lt;Basic Technique&gt; 
       FIG.  9    is an explanatory diagram illustrating a structure of a semiconductor device as a basic technique. An upper diagram of  FIG.  9    is a cross-sectional view, and a lower diagram is a plan view. A cross section taken along line G-G of the lower diagram is the upper diagram. An XYZ orthogonal coordinate system is illustrated in the upper diagram and the lower diagram of  FIG.  9   . In the lower diagram of  FIG.  9   , an insulating film  42  is illustrated as an uppermost layer. 
     In a semiconductor device  59  illustrated in  FIG.  9   , an IGBT is used as a switching element, and an IGBT chip  31  which is a semiconductor chip having the IGBT in the inside is packaged. 
     As illustrated in  FIG.  9   , an emitter electrode  33  is provided on a front surface of the IGBT chip  31 , and a collector electrode  34  is provided on a back surface. The collector electrode  34  as a back surface electrode is electrically connected to a main current wiring  35  via a sub-chip bonding material  47  below. 
     The insulating film  42  is provided on a front surface of the emitter electrode  33  which is a front surface electrode. The insulating film  42  has an opening region OP 42  from the center in the +X direction. The opening region OP 42  has a rectangular shape in which the length in the Y direction is longer than the length in the X direction in plan view. 
     The insulating film  42  further includes an opening region OP 43  in an outer peripheral portion on the −X direction side on a surface of the IGBT chip  31 . The opening region OP 43  has a rectangular shape in which the length in the Y direction is slightly longer than the length in the X direction in plan view, and has a smaller formation area than the opening region OP 42 . 
     In the emitter electrode  33 , a region in the opening region OP 42  is a main current wiring connection region  41 , and a region in the opening region OP 43  is an emitter sense region. 
     An on-chip bonding material  43  is provided on a partial region at the center of the main current wiring connection region  41 . That is, a lower surface S 43  of the on-chip bonding material  43  and a part of a surface region of the main current wiring connection region  41  come into contact with each other, so that an emitter electrode  3  and the on-chip bonding material  43  are electrically connected. Note that a formation area of the lower surface S 43  of the on-chip bonding material  43  is smaller than a surface area of the main current wiring connection region  41 . 
     A main current wiring  36  is provided on the on-chip bonding material  43 , and the main current wiring  36  and the on-chip bonding material  43  are electrically connected. 
     As illustrated in the upper diagram of  FIG.  9   , an emitter sense region of the emitter electrode  33  existing in the opening region OP 43  is electrically connected to a control terminal  32  via a control wire  37 . 
     A gate pad  38  is electrically connected to a gate electrode which is a control electrode of an IGBT (not illustrated), is independently provided on a surface of the IGBT chip  31  without being in contact with the emitter electrode  33 , and has an exposed surface. 
     The gate pad  38  is electrically connected to a gate control terminal (not illustrated) via a gate control wire (not illustrated). 
     As described above, the control terminal  32  for the emitter electrode  33  and the gate control terminal exist as the control terminal of the  1013 T. 
     Al or the like is used as a constituent material of the control wire  37  and the gate control wire, and an emitter sense pad (not illustrated) is generally provided on an emitter sense region in the opening region OP 43  in order to electrically connect the control wire  37  and the collector electrode  34 . That is, by bonding the control wire  37  to a surface of the emitter sense pad, the emitter sense region of the emitter electrode  33  and the control terminal  32  can be electrically connected via the emitter sense pad and the control wire  37 . Similarly to the control wire  37 , the gate control wire is bonded onto a surface of the gate pad  38 . 
     The main current wiring  36  is electrically connected to the main current wiring  35  via the on-chip bonding material  43 , the emitter electrode  33 , the IGBT in the IGBT chip  31 , the collector electrode  34 , and the sub-chip bonding material  47 . 
     Therefore, in the semiconductor device  59 , main current flows from the main current wiring  35  to the main current wiring  36  during operation of the IGBT. The main current wirings  35  and  36  are external wirings for extracting main current flowing through the IGBT. A current path IP 9  illustrated in  FIG.  9    indicates current flow in the main current. 
     As described above, the gate pad  38  and the emitter sense pad are generally provided in an outer peripheral portion of the IGBT chip  31  in consideration of connectivity with a module. That is, the emitter sense pad is provided on an outer peripheral region of the emitter electrode  33 . 
       FIG.  10    is a circuit diagram illustrating an equivalent circuit of the semiconductor device  59  illustrated in  FIG.  9   . In  FIG.  10   , a resistance component of the emitter electrode  33  is considered. Note that, in  FIG.  10   , “ 39 ” means the above-described emitter sense pad. Further, in  FIG.  10   , the gate pad  38  is indicated by “G”, and the emitter sense pad  39  is indicated by “Es”. 
     Actually, a resistance component of the emitter electrode  33  is distributed in all the emitter electrodes  33  except for a region bonded to the on-chip bonding material  43 , but for simplification, in  FIG.  10   , the resistance component is considered as an emitter electrode resistance component R 9  with a lumped constant. That is, the IGBTs in the IGBT chip  31  are classified into two, the IGBT in which collector current Ic2 flows in the main current wiring connection region  41  and the vicinity of the main current wiring connection region  41  is an IGBT  62 , and the IGBT in which collector current Ic1 flows in an outer peripheral region of the emitter electrode  3  away from a main current wiring connection region  11  is an IGBT  61 . Note that the emitter sense pad  39  is provided in an outer peripheral region of the emitter electrode  3 . 
     Therefore, as illustrated in  FIG.  10   , the collectors of the IGBTs  61  and  62  are connected in common to the sub-chip bonding material  47 , and the gates of the IGBTs  61  and  62  are connected in common to the gate pad  38 . 
     On the other hand, the emitter of the IGBT  62  is connected to the on-chip bonding material  43 , and the emitter of the IGBT  61  is connected to the emitter sense pad  39 . The emitter electrode resistance component R 9  exists between the emitters of the IGBTs  61  and  62 . 
     The emitter electrode resistance component R 9  is a resistance component based on a distance from a lower surface of the on-chip bonding material  43  to the emitter sense pad  39  in the emitter electrode  33 . 
     In the semiconductor device  59  having such a configuration, gate voltage VGE1 is applied between the gate pad  38  and the emitter sense pad  39  to put the IGBT in the IGBT chip  31  into an operating state. 
     When the IGBT is in an on state, the collector current Ie1 flows through the IGBT  61 , and the collector current  1   c   2  flows through the IGBT  62 . 
     Since the emitter electrode resistance component R 9  exists between the emitters of the IGBTs  61  and  62 , emitter potential of the IGBT  62  becomes lower than emitter potential of the IGBT  61  due to voltage drop by the emitter electrode resistance component R 9 . 
     As a result, as shown in Equation (1) below, gate voltage VGE2 of the IGBT  62  becomes higher than the gate voltage VGE1. 
         VGE 2= VGE 1+ R 9· Ic 1  (1)
 
     In Equation (1), “R 9 ” is used as a resistance value of the emitter electrode resistance component R 9 , and “Ic2” is used as a current value of the collector current  1   c   2 . 
     As described above, the collector current Ic2 in the semiconductor device  59  tends to increase in accordance with potential distribution in a plane of the emitter electrode  33 . In particular, when large current flows through the IGBT due to short circuit or the like, this tendency becomes remarkable, and thus there has been possibility that the IGBT chip  31  is thermally broken due to increase in the collector current  1   c   2 . 
     As described above, the semiconductor device  59  as a basic technique has a problem of low reliability. 
     On the other hand, in the semiconductor device disclosed in Patent Document 1, focusing on a resistance component of a source electrode corresponding to the emitter electrode  33 , potential of a pad for a source sense is changed from a conventional structure to reduce output variation of a current detection element built in a switching element. However, improvement in reliability of the semiconductor device disclosed in Patent Document 1 has been insufficient. 
     Embodiments described below are intended to solve a problem of the basic technique represented by the semiconductor device  59 . 
     First Embodiment 
       FIGS.  1  and  2    are explanatory diagrams illustrating a structure of a semiconductor device  51  according to a first embodiment of the present disclosure. An upper diagram of  FIG.  1    is a cross-sectional view, and a lower diagram is a plan view, and  FIG.  2    is a plan view. A cross section taken along line A-A of the lower diagram of  FIG.  1    is the upper diagram of  FIG.  1   , and a cross section taken along line B-B of  FIG.  2    is also the upper diagram of  FIG.  1   . An XYZ orthogonal coordinate system is illustrated in the upper diagram and the lower diagram of  FIG.  1   , and  FIG.  2   . 
     The lower diagram of  FIG.  1    is a plan view in which an uppermost part is an insulating film  12 , and  FIG.  2    is a plan view in which an uppermost part is the emitter electrode  3 . 
     In the semiconductor device  51  illustrated in  FIGS.  1  and  2   , an IGBT is used as a switching element, and an IGBT chip  1  which is a semiconductor chip having the IGBT in the inside is packaged. 
     As illustrated in  FIGS.  1  and  2   , the emitter electrode  3  is provided on a surface of the IGBT chip  1 . The emitter electrode  3  is formed in most of a region on a surface of the IGBT chip  1  except for a formation region of a gate pad  8 , an emitter sense pad  9 , and an emitter sense wiring  10 . 
     The collector electrode  4  is provided on a back surface of the IGBT chip  1 . The collector electrode  4  as a back surface electrode is electrically connected to a main current wiring  5  via a sub-chip bonding material  17  provided below. In the main current wiring  5 , a base is below the sub-chip bonding material  17 . 
     The insulating film  12  is provided on a surface of the emitter electrode  3 . The insulating film  12  has an opening region OP 12  from the center in the +X direction. The opening region OP 12  has a rectangular shape in which the length in the Y direction is longer than the length in the X direction in plan view. 
     The insulating film  12  functions as a protective film, and is formed, for example, by applying polyimide onto a surface of the emitter electrode  3 . 
     In the emitter electrode  3 , a region in the opening region OP 12  is the main current wiring connection region  11 . 
     An on-chip bonding material  13  is provided on the entire region of the main current wiring connection region  11 . A lower surface S 13  of the on-chip bonding material  13  has a shape matching a surface shape of the main current wiring connection region  11  in plan view. The on-chip bonding material  13  corresponds to the “chip bonding material”. 
     By contacting the lower surface S 13  of the on-chip bonding material  13  with a surface of the main current wiring connection region  11 , the on-chip bonding material  13  is electrically connected to the emitter electrode  3 . Therefore, the on-chip bonding material  13  is provided on the entire region of a surface of the main current wiring connection region  11 . 
     A main current wiring  6  is provided on the on-chip bonding material  13 , and the main current wiring  6  and the on-chip bonding material  13  are electrically connected. 
     As illustrated in  FIG.  2   , the gate pad  8  is provided on a surface of the IGBT chip  1  without being in contact with the emitter electrode  3 , and the emitter sense pad  9  is provided on a surface of the IGBT chip  1  without being in contact with the gate pad  8  and the emitter electrode  3 . The gate pad  8  and the emitter sense pad  9  are provided in an end portion region on the −X direction side of the IGBT chip  1 . 
     Each of the gate pad  8  and the emitter sense pad  9  has a rectangular shape in which a length in the Y direction is slightly longer than a length in the X direction in plan view. 
     The gate pad  8  is electrically connected to a gate electrode of the IGBT via a gate wiring (not illustrated), and is electrically connected to an external gate control terminal (not illustrated) via a gate control wire (not illustrated). The gate electrode of the IGBT corresponds to the “control electrode of a switching element”. 
     The emitter sense wiring  10  is provided on a surface of the IGBT chip  1  and functions as a sense wiring that electrically connects the emitter electrode  3  and the emitter sense pad  9 . Specifically, the emitter sense wiring  10  is provided to extend in the +X direction from the emitter sense pad  9 , and is in contact with the emitter electrode  3  at a sense connection point  25  which is a side surface of the main current wiring connection region  11  as illustrated in  FIG.  2   . 
     The emitter electrode  3  is provided with a notched region extending in the X direction in a manner not to be in contact with the emitter sense wiring  10  in a location other than the sense connection point  25 . 
     As illustrated in the upper diagram of  FIG.  1   , the emitter sense pad  9  is electrically connected to a control terminal  2  via a control wire  7 . Specifically, by bonding one tip of the control wire  7  to a surface of the emitter sense pad  9 , it is possible to electrically connect the emitter sense pad  9  and the control terminal  2 . 
     Similarly to the control wire  7 , the gate control wire is bonded onto a surface of the gate pad  8 . Note that Al or the like is used as a constituent material of the control wire  7  or the gate control wire. 
     As described above, the control terminal  2  for the emitter electrode  3  and the gate control terminal exist as a control terminal of the IGBT which is a switching element in the IGBT chip  1 . 
     The main current wiring  6  is electrically connected to the main current wiring  5  via the on-chip bonding material  13 , the emitter electrode  3 , the IGBT in the IGBT chip  1 , the collector electrode  4 , and the sub-chip bonding material  17 . 
     Therefore, in the semiconductor device  51  of the first embodiment, main current flows as collector current from the main current wiring  5  to the main current wiring  6  during operation of the IGBT in the TORT chip  1 . The main current wirings  5  and  6  are external wirings for extracting main current flowing through the IGBT. A current path IP 1  illustrated in  FIGS.  1  and  2    illustrates current flow in main current. 
     In the semiconductor device  51 , the emitter electrode  3 , the emitter sense pad  9 , and the emitter sense wiring  10  are integrally formed on a surface of the IGBT chip  1 . 
     On the other hand, as illustrated in  FIGS.  1  and  2   , in the IGBT chip  1 , constituent elements of the IGBT are not formed in an ineffective region  20  below the emitter sense pad  9  and the emitter sense wiring  10 . The ineffective region  20  is a region where the IGBT as a switching element does not function. Note that a field insulating film for element isolation may be formed as the ineffective region  20 . 
     Further, a region below the gate pad  8  in the IGBT chip  1  is also the ineffective region  20  where the IGBT does not function. 
       FIG.  3    is a circuit diagram illustrating an equivalent circuit of the semiconductor device  51  illustrated in  FIGS.  1  and  2   . In  FIG.  3   , a resistance component of the emitter electrode  3  is considered. Further, in  FIG.  3   , the gate pad  8  is indicated by “G”, and the emitter sense pad  9  is indicated by “Es”. 
     Actually, a resistance component of the emitter electrode  3  is distributed in all the emitter electrodes  3  except for the main current wiring connection region  11  bonded to the lower surface S 13  of the on-chip bonding material  13 , but for simplification, in  FIG.  3   , the resistance component is considered as an emitter electrode resistance component R 1  with a lumped constant. That is, the IGBTs in the IGBT chip  1  are classified into two, the IGBT in which collector current Ic2 flows in the main current wiring connection region  11  and the vicinity of the main current wiring connection region  11  is the IGBT  62 , and the IGBT in which collector current Ic1 flows in an outer peripheral region of the emitter electrode  3  away from the main current wiring connection region  11  is the IGBT  61 . This outer peripheral region is a surface electrode remote region. 
     Therefore, as illustrated in  FIG.  3   , the collectors of the IGBTs  61  and  62  are connected in common to the sub-chip bonding material  17 , and the gates which are control electrodes of the IGBTs  61  and  62  are connected in common to the gate pad  8 . 
     On the other hand, the emitter and the emitter sense pad  9  of the IGBT  62  are electrically connected to the main current wiring connection region  11 . At this time, the emitter electrode resistance component R 1  exists between the emitter of the IGBT  61  and the emitter of the IGBT  61 . 
     In the emitter electrode  3 , the emitter electrode resistance component R 1  is a resistance component based on a distance from the lower surface S 13  of the on-chip bonding material  13 , that is, a distance from the main current wiring connection region  11  to the surface electrode remote region of the emitter electrode  3 . Therefore, the emitter of the IGBT  61  is connected to the main current wiring connection region  11  via the emitter electrode resistance component R 1 . 
     In the semiconductor device  51  having such an equivalent circuit, the gate voltage VGE2 is applied between the gate pad  8  and the emitter sense pad  9  to bring the IGBT in the IGBT chip  1  into an operating state. Here, potential obtained from the emitter sense pad  9  is control reference potential. 
     That is, the IGBT has the gate which is a control electrode, and the operation of the GIBT is controlled by applying the gate voltage VGE2 which is control voltage with potential of the emitter electrode  3  as reference potential to the gate of the IGBT. As described above, in the semiconductor device  51 , the gate voltage VGE2 becomes control voltage for the IGBT. 
     When the IGBT in the IGBT chip  1  is in an on state, the collector current Ic1 flows through the IGBT  61 , and the collector current Ic2 flows through the IGBT  62 . The sum of the collector current Ic1 and the collector current Ic2 is main current of the IGBT. 
     On the other hand, since the IGBT chip  1  has the ineffective region  20  below the emitter sense pad  9  and the emitter sense wiring  10 , emitter potential of the IGBT  62  is not affected by main current. 
     By forming the emitter sense pad  9  and the emitter sense wiring  10  on the ineffective region  20 , main current does not flow through the emitter sense wiring  10 , and charge/discharge current mainly flows through the gate of the IGBT. Since charge/discharge current of the gate has a current amount smaller than main current by two or three orders of magnitude, voltage drop due to current flowing through the emitter sense wiring  10  becomes a negligible level, and as a result, control reference potential, which is potential of the emitter sense pad  9 , is not affected by the main current. 
     Since the emitter electrode resistance component R 1  exists between the emitters of the IGBTs  61  and  62 , voltage drop due to the emitter electrode resistance component R 1  occurs between the IGBTs  61  and  62 . The semiconductor device  51  has a reference potential increase characteristic in which emitter potential of the IGBT  61  becomes relatively higher than emitter potential of the IGBT  62  due to the voltage drop. This reference potential increase characteristic corresponds to the “reference potential fluctuation characteristic”. 
     That is, remote region reference potential in a surface electrode remote region relatively away from the main current wiring connection region  11  is affected by the emitter electrode resistance component R 1  based on a distance from the main current wiring connection region  11 , and has a reference potential increase characteristic higher than control reference potential. 
     As a result, as shown in Equation (2), the gate voltage VGE1 of the IGBT  61  becomes lower than the gate voltage VGE2. 
         VGE 1= VGE 2− R 1· Ic 1  (2)
 
     In Equation (2), “R 1 ” is used as a resistance value of the emitter electrode resistance component R 1 , and “Ic1” is used as a current value of the collector current  1   c   1 . 
     As shown in Equation (2), emitter potential of the IGBT  61  increases by (R 1 ·Ic1) due to a reference potential increase characteristic, so that the gate voltage VGE1 of the IGBT  61  becomes lower than the gate voltage VGE2. As a result, the collector current Ic1 flowing through the IGBT  61  can be reduced. 
     As described above, the IGBT  61  has a reference potential increase characteristic based on potential distribution in a plane of the emitter electrode  3 . In particular, when large current flows through the IGBT due to a short circuit or the like, this reference potential increase characteristic becomes remarkable. 
     Therefore, when large current is about to flow through the IGBT due to a short circuit or the like, the collector current Ic1 flowing through the IGBT  61  decreases due to the reference potential increase characteristic, so that increase in main current of the IGBT can be effectively suppressed. 
     As described above, in the semiconductor device  51 , by applying negative feedback to the gate voltage VGE1 of the IGBT  61  by the emitter electrode resistance component R 1  at the time of large current energization of a short circuit or the like, increase in main current can be effectively suppressed, and reliability of the device can be improved. 
     That is, in the semiconductor device  51 , even when large current of a short circuit or the like flows and the collector current Ic2 increases, current control is performed so that the collector current Ic1 decreases, and (Ic1+Ic2), which is the total amount of collector current, is suppressed, so that reliability of the device can be improved. 
     Then, a value of the emitter electrode resistance component R 1  can be optionally adjusted by designing the dimension of the opening region OP 12  of the insulating film  12 . For example, if a surface area of the main current wiring connection region  11  is reduced by reduction in the dimension of the opening region OP 12 , the emitter electrode resistance component R 1  is increased, and the reference potential increase characteristic can be enhanced. 
     However, although the emitter electrode resistance component R 1  is minute, a power loss occurs. For this reason, in application to an actual semiconductor device, it is necessary to appropriately design the dimension of the opening region OP 12  in consideration of a trade-off between degree of a current amount reduction tendency of the collector current Ic1 and increase in power loss. 
     On the other hand, in a case where the emitter electrode  3  and the on-chip bonding material  13  are electrically connected only in a partial region of a surface of the main current wiring connection region  11 , magnitude of the emitter electrode resistance component R 1  changes depending on an area in contact with the on-chip bonding material  13  in a surface region of the main current wiring connection region  11 . For this reason, optimum design becomes difficult. 
     In view of the above, in the semiconductor device  51  of the first embodiment, a surface shape of the lower surface S 13  of the on-chip bonding material  13  is matched with a surface shape of the main current wiring connection region  11 , and the entire region of a surface of the main current wiring connection region  11  and the lower surface S 13  of the on-chip bonding material  13  are bonded. 
     That is, the semiconductor device  51  realizes the entire surface bonding structure in which the entire region of a surface of the main current wiring connection region  11  existing in the opening region OP 12  of the insulating film  12  and the lower surface S 13  of the on-chip bonding material  13  are brought into contact with each other to achieve electrical connection between the emitter electrode  3  and the on-chip bonding material  13 . 
     For this reason, in the semiconductor device  51  of the first embodiment, the emitter electrode resistance component R 1  can be accurately set according to the dimension of the opening region OP 12 . 
     In order to realize the entire surface bonding structure described above, it is desirable to reliably provide the on-chip bonding material  13  in the opening region OP 12  of the insulating film  12  without a gap at the time of assembling the semiconductor device  51 . For this reason, in the first embodiment, a surface shape of the lower surface S 13  of the lower surface S 13  matches a surface of the main current wiring connection region  11 . 
     For example, when solder is used as the on-chip bonding material  13 , the on-chip bonding material  13  having the lower surface S 13  in contact with the entire surface of the main current wiring connection region  11  can be obtained by plating the inside of the opening region OP 12  of the insulating film  12  and embedding the on-chip bonding material  13  in the opening region OP 12  without a gap. 
     As described above, the semiconductor device  51  according to the first embodiment has features (1) to (3) below.
         (1) The lower surface S 13  of the on-chip bonding material  13  has a shape matching a surface shape of the main current wiring connection region  11  in plan view.   (2) The emitter sense wiring  10  is directly connected to a side surface of the main current wiring connection region  11 .   (3) The IGBT chip  1  has the ineffective region  20  in which the IGBT does not function in a region below the emitter sense pad  9  and the emitter sense wiring  10 .       

     Note that, regarding the above-described features (1) to (3), the on-chip bonding material  13  corresponds to the “chip bonding material”, the main current wiring connection region  11  corresponds to the “wiring connection region”, the emitter sense wiring  10  corresponds to the “sense wiring”, the IGBT chip  1  corresponds to the “semiconductor chip”, the emitter sense pad  9  corresponds to the “sense pad”, and the IGBT corresponds to the “switching element”. 
     Since the semiconductor device  51  of the first embodiment has the above-described features (1) to (3), control reference potential obtained from the emitter sense pad  9  during operation of the IGBT is not affected by the emitter electrode resistance component R 1  based on a distance from the main current wiring connection region  11 . 
     Therefore, assuming that a voltage value of original gate-emitter voltage in the IGBT in the IGBT chip  1  is a control voltage value VG0, the gate voltage VGE2 is equal to the control voltage value VG0. 
     On the other hand, in the emitter electrode  3  of the semiconductor device  51 , emitter potential of the IGBT  61  is affected by the emitter electrode resistance component R 1  based on a distance from the main current wiring connection region  11 , and has a reference potential increase characteristic higher than emitter potential of the IGBT  62 . 
     Therefore, the gate voltage VGE1 of the IGBT  61  is lower than the gate voltage VGE2 as shown in Equation (2) described above. 
     Here, emitter potential of the IGBT  61  corresponds to the “remote region reference potential” in a surface electrode remote region relatively away from the main current wiring connection region  11 , emitter potential of the IGBT  62  corresponds to the control reference potential obtained from the emitter sense pad  9 , and the “reference potential increase characteristic” corresponds to the “reference potential fluctuation characteristic”. 
     Therefore, in the semiconductor device  51  according to the first embodiment, when large current flows as main current flowing through the emitter electrode  3  at the time of a short circuit or the like, a current amount of the collector current Ic1 flowing through a surface electrode remote region can be reduced according to the reference potential increasing characteristic. 
     As a result, the semiconductor device  51  of the first embodiment can effectively suppress increase in a current amount of main current of the IGBT by reduction in the collector current Ic1, and improve reliability of the device. 
     Note that, regarding the above-described effect of the first embodiment, the emitter electrode  3  corresponds to the “surface electrode”. Further, in a case where the IGBTs in the IGBT chip  1  are classified into the IGBTs  61  and  62 , the gate voltage VGE2 corresponds to the “control voltage” for the IGBT  62 , and the gate voltage VGE1 corresponds to the “control voltage” for the IGBT  61 . 
     Second Embodiment 
       FIG.  4    is an explanatory diagram illustrating a structure of a semiconductor device  52  according to a second embodiment of the present disclosure. The upper diagram of  FIG.  4    is a cross-sectional view, and the lower diagram is a plan view. A cross section taken along line C-C of the lower diagram of  FIG.  4    is the upper diagram of  FIG.  4   , and an XYZ orthogonal coordinate system is described in each of the upper diagram and the lower diagram of  FIG.  4   . 
     In the semiconductor device  52  illustrated in  FIG.  4   , an IGBT is used as a switching element, and an IGBT chip  1 B which is a semiconductor chip having the IGBT in the inside is packaged. 
     As illustrated in  FIG.  4   , the emitter electrode  3  is provided on a front surface of the IGBT chip  1 B, and the collector electrode  4  is provided on a back surface. The collector electrode  4  serving as a back surface electrode is electrically connected to the main current wiring  5  via the sub-chip bonding material  17 . 
     One end of each of a plurality of main current wires  14  is electrically connected to the emitter electrode  3  by contacting at a corresponding chip connection point  23 B among a plurality of the chip connection points  23 B on a surface of the emitter electrode  3 . A plurality of there chip connection points  23 B are discretely provided near the center in the X direction along the Y direction. In this manner, one end of each of plurality of the main current wires  14  is bonded on a surface of the emitter electrode  3 . The other end of a plurality of the main current wires  14  is bonded on a surface of the main current wiring  6 . A plurality of the main current wires  14  correspond to the “plurality of chip wires”. 
     One end of a control wire  7 B is electrically connected to the emitter electrode  3  by contacting at a sense connection point  25 B on a surface of the emitter electrode  3 . That is, one end of the control wire  7 B is bonded on a surface of the emitter electrode  3 . 
     Further, as illustrated in the lower diagram of  FIG.  4   , the sense connection point  25 B is provided near the third and fourth chip connection points  23 B from the +Y direction side among a plurality of the chip connection points  23 B. Note that the control wire  7 B and a plurality of the main current wires  14  are provided in an electrically independent manner without being in contact with each other. The other end of the control wire  7 B is bonded to the control terminal  2 . 
     Here, a region including a plurality of the chip connection points  23 B in the emitter electrode  3  is defined as the main current wiring connection region  11 B, and a position farthest from the main current wiring connection region  11 B in the emitter electrode  3  is defined as an electrode remote position. In the emitter electrode  3  illustrated in  FIG.  4   , an outer peripheral surface on the −X side is at the electrode remote position. Note that the emitter electrode  3  corresponds to the “surface electrode”, and the main current wiring connection region  11 B corresponds to the “wiring connection region”. 
     The sense connection point  25 B satisfies a connection point arrangement condition that the connection point is provided at a position close to the chip connection point  23 B between the chip connection point  23 B and the electrode remote position. 
     The sense connection point  25 B only needs to satisfy the connection point arrangement condition in a relationship with at least one of a plurality of the main current wires  14 . Further, potential obtained from the sense connection point  25 B is the control reference potential. 
     As illustrated in  FIG.  4   , the gate pad  8  is provided on a surface of the IGBT chip  1 B without being in contact with the emitter electrode  3 . The gate pad  8  is provided in an end portion region on the −X direction side of the IGBT chip  1 B. The gate pad  8  has a rectangular shape in which a length in the Y direction is slightly longer than a length in the X direction in plan view. Further, a region below the gate pad  8  in the IGBT chip  1 B is an ineffective region where the IGBT does not function. 
     The gate pad  8  is electrically connected to a gate electrode of the IGBT via a gate wiring (not illustrated), and is electrically connected to a gate control terminal (not illustrated) via a gate control wire (not illustrated). 
     The gate control wire is bonded onto a surface of the gate pad  8 . Note that Al or the like is used as a constituent material of the control wire  7 B, the main current wire  14 , and the gate control wire. 
     As described above, similarly to the first embodiment, the second embodiment includes the control terminal  2  for the emitter electrode  3  and the gate control terminal as a control terminal of the  16137  which is a switching element in the IGBT chip  1 B. 
     The main current wiring  6  is electrically connected to the main current wiring  5  via a plurality of the main current wires  14 , the emitter electrode  3 , the IGBT in the IGBT chip  1 B, the collector electrode  4 , and the sub-chip bonding material  17 . 
     Therefore, re, in the semiconductor device  52  of the second embodiment, main current flows as collector current from the main current wiring  5  to the main current wiring  6  during operation of the IGBT in the IGBT chip  1 B. The main current wirings  5  and  6  are external wirings for extracting main current flowing through the IGBT. A current path IP 2  illustrated in  FIG.  4    indicates current flow in the main current. 
     The semiconductor device S 2  of the second embodiment appears in an equivalent circuit illustrated in  FIG.  3    as in the first embodiment. However, the main current wiring connection region  11  illustrated in  FIG.  3    is replaced with the main current wiring connection region  11 B, and the emitter sense pad  9  is replaced with the sense connection point  25 B. 
     That is, regarding the IGBTs in the IGBT chip  1 B, the IGBT in which collector current Ic2 flows in the main current wiring connection region  11 B and the vicinity of the main current wiring connection region  11 B is the IGBT  62 , and the IGBT in which collector current Ic1 flows in an outer peripheral region of the emitter electrode  3  away from the main current wiring connection region  11 B is the IGBT  61 . This outer peripheral region is a surface electrode remote region. 
     Note that, in order to make the equivalent circuit of the semiconductor device  52  as a circuit illustrated in  FIG.  3   , it is desirable to arrange the sense connection point  25 B close to any of a plurality of the chip connection points  23 B. That is, it is desirable to arrange the sense connection point  25 B close to any of a plurality of the chip connection points  23 B to an extent that a resistance component between the sense connection point  25 B and the main current wiring connection region  11 B can be ignored. 
     Therefore, similarly to the semiconductor device  51 , the semiconductor device  52  of the second embodiment can effectively suppress increase in main current and improve reliability of the device by applying negative feedback to the gate voltage VGE1 of the IGBT  61  by the reference potential increase characteristic of the IGBT  61  at the time of large current energization of a short circuit or the like. 
     As described above, the semiconductor device  52  according to the second embodiment has a feature (4) below.
         (4) The sense connection point  25 B of the control wire  7 B satisfies a connection point arrangement condition that the connection point is provided at a position close to the chip connection point  23 B between the chip connection point  23 B and the electrode remote position in the emitter electrode  3 .       

     Note that regarding the above-described feature (4), the control wire  7 B corresponds to the “sense connection member” or the “sense wire”, and the emitter electrode  3  corresponds to the “surface electrode”. 
     The semiconductor device  52  according to the second embodiment has the above-described feature (4). Therefore, in the semiconductor device  52 , by arranging the sense connection point  25 B close to one connection point among a plurality of the chip connection points  23 B, control reference potential obtained from the sense connection point  25 B is hardly affected by the emitter electrode resistance component R 1  based on a distance from the main current wiring connection region  11 B during operation of the IGBT. 
     Therefore, assuming that a voltage value of original gate-emitter voltage in the IGBT in the IGBT chip  1 B is the control voltage value VG0, the gate voltage VGE2 is equal to the control voltage value VG0. 
     On the other hand, in the emitter electrode  3  of the semiconductor device  52 , emitter potential of the IGBT  61  is affected by the emitter electrode resistance component R 1  based on a distance from the main current wiring connection region  11 B, and has a reference potential increase characteristic higher than emitter potential of the IGBT  62 . 
     Therefore, the gate voltage VGE1 of the IGBT  61  is lower than the gate voltage VGE2 as shown in Equation (2) described above. 
     Here, the emitter potential of the IGBT  61  corresponds to the “remote region reference potential” in a surface electrode remote region relatively away from a wire connection region. 
     Therefore, in the semiconductor device  52  according to the second embodiment, when large current flows as main current flowing through the emitter electrode  3  at the time of a short circuit or the like, a current amount of the collector current Ic1 flowing through a surface electrode remote region can be reduced according to the reference potential increasing characteristic of the IGBT  61 . 
     As a result, the semiconductor device  52  of the second embodiment can effectively suppress increase in a current amount of main current of the IGBT by reduction in the collector current Ic1, and improve reliability of the device. 
     Furthermore, in the semiconductor device  52  according to the second embodiment, electrical connection between the sense connection point  25 B of the emitter electrode  3  and the control terminal  2  can be relatively easily achieved by the control wire  7 B. 
     In addition, in the semiconductor device  52  according to the second embodiment, relatively large main current can be taken out to the outside by establishing electrical connection with the emitter electrode  3  by a plurality of the main current wires  14 . 
     Note that, regarding the above-described effect of the second embodiment, the emitter electrode  3  corresponds to the “surface electrode”. Further, in a case where the IGBTs in the IGBT chip  1  are classified into the IGBTs  61  and  62 , the gate voltage VGE2 corresponds to the “control voltage” for the IGBT  62 , and the gate voltage VGE1 corresponds to the “control voltage” for the IGBT  61 . Furthermore, the control wire  7 B corresponds to the “sense bonding member” or the “sense wire”, and the main current wire  14  corresponds to the “chip wire”. 
     The sense connection point  25 B of the control wire  7 B can exhibit the above effect by satisfying the above-described connection point arrangement condition. 
     However, when the semiconductor device  52  of the second embodiment exerts the above effect, it is desirable that the sense connection point  25 B be as close as possible to any of a plurality of the chip connection points  23 B. This is because the emitter electrode resistance component R 1  of the emitter electrode  3  can be increased to enhance the effect of suppressing a current amount of main current. 
     Furthermore, the sense connection point  25 B is desirably close to a connection point existing at the center of the emitter electrode  3  among a plurality of the chip connection points  23 B. 
     This is because, on the emitter electrode  3 , a potential difference between the sense connection point  25 B and each of the chip connection points  23 B existing at both ends in the Y direction can be minimized. 
     Third Embodiment 
       FIG.  5    is an explanatory diagram illustrating a structure of a semiconductor device  53  according to a third embodiment of the present disclosure. The upper diagram of  FIG.  5    is a cross-sectional view, and the lower diagram is a plan view. A cross section taken along line D-D of the lower diagram of  FIG.  5    is the upper diagram of  FIG.  5   , and an XYZ orthogonal coordinate system is described in each of the upper diagram and the lower diagram of  FIG.  5   . 
     In the semiconductor device  53  illustrated in  FIG.  5   , an IGBT is used as a switching element, and an IGBT chip  1 C which is a semiconductor chip having the IGBT in the inside is packaged. Hereinafter, the same portions as those of the semiconductor device  52  illustrated in  FIG.  4    will be denoted by the same reference numerals and omitted from description as appropriate, and a feature portion of the semiconductor device  53  will be mainly described. 
     As illustrated in  FIG.  5   , the gate pad  8  is provided on a surface of the IGBT chip  1 C without being in contact with the emitter electrode  3 , and the emitter sense pad  9  is provided on a surface of the IGBT chip  1 C without being in contact with the gate pad  8  and the emitter electrode  3 . The gate pad  8  and the emitter sense pad  9  are provided in an end portion region on the −X direction side of the IGBT chip  1 C. 
     Each of the gate pad  8  and the emitter sense pad  9  has a rectangular shape in which a length in the Y direction is slightly longer than a length in the X direction in plan view. 
     The gate pad  8  is electrically connected to a gate electrode of the IGBT via a gate wiring (not illustrated), and is electrically connected to a gate control terminal (not illustrated) via a gate control wire (not illustrated). 
     The emitter sense wiring  10  is provided on a surface of the IGBT chip  1 C and is a sense wiring that electrically connects the emitter electrode  3  and the emitter sense pad  9 . Specifically, the emitter sense wiring  10  is provided to extend in the +X direction from the emitter sense pad  9 , and is in direct contact with the emitter electrode  3  at a sense connection point  25 C which is a side surface of the main current wiring connection region  11 . 
     The emitter electrode  3  is provided with a notched region extending in the X direction in a manner not to be in contact with the emitter sense wiring  10  in a location other than the sense connection point  25 C. 
     The sense connection point  25 C satisfies a connection point arrangement condition that the connection point is provided at a position close to the chip connection point  23 B between the chip connection point  23 B and the electrode remote position in the emitter electrode  3 . 
     The sense connection point  25 C only needs to satisfy the connection point arrangement condition in a relationship with at least one of a plurality of the main current wires  14 . 
     As illustrated in the lower diagram of  FIG.  5   , the sense connection point  25 C is provided near the fifth chip connection points  23 B from the +Y direction side among a plurality of the chip connection points  23 B, and satisfies the connection point arrangement condition. 
     As illustrated in the upper diagram of  FIG.  5   , the emitter sense pad  9  is electrically connected to the control terminal  2  via the control wire  7 . Specifically, by bonding a tip of the control wire  7  to a surface of the emitter sense pad  9 , it is possible to electrically connect the emitter sense pad  9  and the control terminal  2 . 
     Note that Al or the like is used as a constituent material of the control wire  7 , the main current wire  14 , and the gate control wire. 
     Furthermore, in the IGBT chip  1 C, constituent elements of the IGBT are not formed in an ineffective region  20 C below the emitter sense pad  9  and the emitter sense wiring  10 . The ineffective region  20 C is a region where the IGBT as a switching element does not function. 
     Furthermore, a region below the gate pad  8  in the IGBT chip  1 C is also the ineffective region  20 C where the IGBT does not function. 
     As described above, similarly to the first and second embodiments, the third embodiment includes the control terminal  2  for the emitter electrode  3  and the gate control terminal as a control terminal of the IGBT which is a switching element in the IGBT chip  1 C. 
     The main current wiring  6  is electrically connected to the main current wiring  5  via a plurality of the main current wires  14 , the emitter electrode  3 , the IGBT in the IGBT chip  1 C, the collector electrode  4 , and the sub-chip bonding material  17 . 
     Therefore, in the semiconductor device  53  of the third embodiment, main current flows as collector current from the main current wiring  5  to the main current wiring  6  during operation of the IGBT in the IGBT chip  1 C. The main current wirings  5  and  6  are external wirings for extracting main current flowing through the IGBT. A current path IP 3  illustrated in  FIG.  5    indicates current flow in the main current. 
     The semiconductor device  53  of the third embodiment appears in the equivalent circuit illustrated in  FIG.  3    as in the first and second embodiments. However, the main current wiring connection region  11  illustrated in  FIG.  3    is replaced with the main current wiring connection region  11 B. 
     Therefore, in the semiconductor device  53  of the third embodiment, reliability of the device can be improved similarly to the semiconductor device  51  and the second embodiment. 
     The semiconductor device  53  according to the third embodiment further has an effect described below. In the embodiment  52  of the second embodiment, in order to avoid interference between the control wire  7 B and a plurality of the main current wires  14 , it is necessary to set a distance between the sense connection point  25 B of the control wire  7 B and the chip connection point  23 B of the main current wire  14  to a certain distance or more. 
     On the other hand, in the third embodiment, as the sense connection member, the gate pad  8  and the emitter sense pad  9  are used instead of the control wire  7 B. Therefore, in the semiconductor device  53 , since no interference occurs even if the sense connection point  25 C is brought close to the chip connection point  23 B, a distance between the chip connection point  23 B and the sense connection point  25 C is shortened, the emitter electrode resistance component R 1  is increased, and a current amount suppression effect of main current can be enhanced. 
     As described above, in the semiconductor device  53  according to the third embodiment, the emitter sense wiring  10  is connected at the sense connection point  25 C relatively close to the chip connection point  23 B, so that electrical connection to the emitter electrode  3  can be achieved in a stable manner. 
     In addition, since the IGBT chip  1 C has the ineffective region  20 C in which the IGBT does not function in a region below the emitter sense pad  9  and the emitter sense wiring  10 , emitter potential of the IGBT  62  is not affected by main current in the equivalent circuit illustrated in  FIG.  3   . 
     Note that, regarding the above-described effect of the third embodiment, the emitter sense wiring  10  corresponds to the “sense wiring”, the emitter electrode  3  corresponds to the “surface electrode”, the IGBT chip  1 C corresponds to the “semiconductor chip”, the emitter sense pad  9  corresponds to the “sense pad”, the emitter sense wiring  10  corresponds to the “sense wiring”, and the IGBT corresponds to the “switching element”. 
     Further, emitter potential of the IGBT  62  is control reference potential obtained from the emitter sense pad  9 . 
     Fourth Embodiment 
       FIGS.  6  and  7    are explanatory diagrams illustrating a structure of a semiconductor device  54  according to a fourth embodiment of the present disclosure. An upper diagram of  FIG.  6    is a cross-sectional view, and a lower diagram is a plan view, and  FIG.  7    is a plan view. A cross section taken along line E-E of the lower diagram of  FIG.  6    is the upper diagram of  FIG.  6   , and a cross section taken along line F-F of  FIG.  7    is also the upper diagram of  FIG.  6   . An XYZ orthogonal coordinate system is illustrated in the upper diagram and the lower diagram of  FIG.  6   , and  FIG.  7   . 
     The lower diagram of  FIG.  6    is a plan view in which an uppermost part is the insulating film  12 , and  FIG.  7    is a plan view in which an uppermost part is the emitter electrode  3 . 
     In the semiconductor device  54  illustrated in  FIGS.  6  and  7   , an IGBT is used as a switching element, and an IGBT chip  1 D which is a semiconductor chip having the IGBT in the inside is packaged. 
     Hereinafter, the same portions as those of the semiconductor device  51  of the first embodiment illustrated in  FIGS.  1  and  2    will be denoted by the same reference numerals and omitted from description as appropriate, and a feature portion of the semiconductor device  54  will be mainly described. A current path IP 4  illustrated in  FIGS.  6  and  7    illustrates current flow in main current. 
     The semiconductor device  54  according to the fourth embodiment has features (5) to (7) below in addition to the features (1) to (3) of the semiconductor device  51 .
         (5) The IGBT chip  1 D further includes a current detection IGBT that performs switching operation equivalent to the original IGBT, and the current detection IGBT is provided in a current detection element formation region  27  of the IGBT chip  1 D.   (6) A current detection output pad  15  which is provided on a surface of the current detection element formation region  27  of the IGBT chip  1 D without being in contact with the emitter electrode  3  and through which detection current flows during operation of the current detection IGBT is further provided.   (7) Current obtained from the current detection output pad  15  is sense current Is.       

     Note that, regarding the above-described features (5) to (7), the IGBT chip  1 D corresponds to the “semiconductor chip”, the IGBT corresponds to the “switching element”, the current detection IGBT corresponds to the “current detection element”, the emitter electrode  3  corresponds to the “surface electrode”, and the current detection output pad  15  corresponds to the “current detection pad”. 
     Further, like in the first embodiment, constituent elements of the IGBT are not formed in an ineffective region  20 D below the emitter sense pad  9  and the emitter sense wiring  10 . The ineffective region  20 D is a region where the IGBT as a switching element does not function. 
     Furthermore, a region below the gate pad  8  in the IGBT chip  1 D is also the ineffective region  20 D where the IGBT does not function. 
     In addition, in the IGBT chip  1 D, the ineffective region  20 D is also formed around the current detection element formation region  27 . Since the ineffective region  20 D functions as an element isolation region, the current detection IGBT in the current detection element formation region  27  is provided independently of the original IGBT below the emitter electrode  3 . 
     The current detection output pad  15  is provided on the current detection element formation region  27  without being in contact with the emitter electrode  3 , the gate pad  8 , and the emitter sense pad  9 , functions as an emitter electrode of the current detection IGBT, and is electrically connected to a control terminal  2 I) via a control wire  7 D as illustrated in the upper diagram of  FIG.  6   . In this manner, the current detection output pad  15  is provided independently of the emitter electrode  3 . 
       FIG.  8    is a circuit diagram illustrating an equivalent circuit of the semiconductor device  54  illustrated in  FIGS.  6  and  7   . In  FIG.  8   , a resistance component of the emitter electrode  3  is considered. Further, in  FIG.  8   , the gate pad  8  is indicated by “G”, the emitter sense pad  9  is indicated by “Es”, and the current detection output pad  15  is indicated by “S”. 
     For simplification, in  FIG.  8   , the emitter electrode resistance component R 1  is considered as a lumped constant. That is, the IGBTs in the IGBT chip  1 D are classified into two, the IGBT in which collector current Ic2 flows in the main current wiring connection region  11  and the vicinity of the main current wiring connection region  11  is the IGBT  62 , and the IGBT in which collector current Ic1 flows in an outer peripheral region of the emitter electrode  3  away from the main current wiring connection region  11  is the IGBT  61 . This outer peripheral region is a surface electrode remote region. 
       FIG.  11    is a circuit diagram illustrating an equivalent circuit of a semiconductor device  59 B for comparison having a current detection function similarly to the semiconductor device  54 . The semiconductor device  59 B has a configuration in which the current detection output pad  15  is added to the semiconductor device  59  of the basic technique illustrated in  FIGS.  9  and  10   . Further, in  FIG.  11   , the gate pad  38  is indicated by “G”, the emitter sense pad  39  is indicated by “Es”, and the current detection output pad  15  is indicated by “S”. 
     In  FIG.  11   , the emitter electrode resistance component R 9  is considered as a lumped constant. That is, the IGBTs in the IGBT chip  31  are classified into two, the IGBT in which the collector current Ic2 flows in the main current wiring connection region  41  and the vicinity of the main current wiring connection region  41  is the IGBT  62 , and the IGBT in which the collector current Ic1 flows in the emitter sense pad  39  and in the vicinity of the emitter sense pad  39  is the IGBT  61 . 
     Further, in both  FIGS.  8  and  11   , the current detection IGBT is an IGBT  63 , the gate of the IGBT  63  is connected to the gate pad  8 , and the emitter is connected to the current detection output pad  15  without passing through the emitter electrode resistance component R 1  or R 9 . Here, current flowing through the IGBT  63  is referred to as the sense current Is. 
     Furthermore, the current detection output pad  15  and the emitter sense pad  9  or the emitter sense pad  39  are short-circuited to simplify the description. 
     Similarly to the equivalent circuit of the semiconductor device  59  illustrated in  FIG.  10   , the semiconductor device  59 B is affected by the emitter electrode resistance component R 9 , and the collector current Ic2 of the IGBT  62  tends to increase. 
     On the other hand, both the gate voltage VGE1 of the IGBT  61  and gate voltage VGE3 of the IGBT  63  are not affected by the emitter electrode resistance component R 9 . 
     Therefore, assuming that a voltage value of original gate-emitter voltage in the IGBT in the IGBT chip  31  is the control voltage value VG0, both the gate voltage VGE1 and the gate voltage VGE3 are equal to the control voltage value VG0. 
     For this reason, in the semiconductor device  59 B, the collector current Ic1 and the sense current Is are not affected by increase in the collector current Ic2. 
     That is, the semiconductor device  59 B has a detection characteristic in which the collector current Ic1 can be accurately detected based on the sense current Is, but the collector current Ic2 cannot be accurately detected based on the sense current Is. 
     Therefore, in the semiconductor device  59 B, in a case where main current (=Ic1+Ic2) of the IGBT increases, detection sensitivity of the main current by the sense current Is relatively decreases as much as increase in a current ratio of the collector current Ic2 in the main current. 
     On the other hand, similarly to the semiconductor device  51 , the semiconductor device  54  of the fourth embodiment is affected by the emitter electrode resistance component R 1 , and the collector current Ic1 of the IGBT  61  tends to decrease. 
     On the other hand, similarly to the semiconductor device  51 , the gate voltage VGE2 of the IGBT  62  is not affected by the emitter electrode resistance component R 1  in the semiconductor device  54 . 
     Furthermore, the gate voltage VGE3 of the IGBT  63  is also not affected by the emitter electrode resistance component R 1 . This is because the current detection element formation region  27  is below the current detection output pad  15 , and the current detection output pad  15  can be formed to be relatively small, so that the gate voltage VGE3 during operation of the current detection IGBT is hardly affected by a resistance component of the current detection output pad  15 . 
     Therefore, assuming that a voltage value of original gate-emitter voltage in the IGBT in the IGBT chip  1 D is the control voltage value VG0, both the gate voltage VGE2 and the gate voltage VGE3 are equal to the control voltage value VG0. 
     For this reason, in the semiconductor device  54  of the fourth embodiment, the collector current Ic2 and the sense current Is are not affected by decrease in the collector current Ic1. 
     The semiconductor device  54  has a detection characteristic in which the collector current Ic2 can be accurately detected based on the sense current Is, but the collector current Ic1 cannot be accurately detected based on the sense current Is. 
     Therefore, in the semiconductor device  54  of the fourth embodiment, in a case where main current (=Ic1+Ic2) of the IGBT increases, as much as a current ratio of the collector current Ic1 in the main current decreases and a current ratio of the collector current Ic2 increases, detection sensitivity of the main current based on the sense current Is becomes relatively high. 
     In the semiconductor device  54  of the fourth embodiment, when the main current flows through the emitter electrode  3  of the IGBT, the gate voltage VGE1 becomes lower than the gate voltage VGE2, and a current amount of the collector current Ic1 flowing through the surface electrode remote region decreases. 
     On the other hand, since the gate voltage VGE1 and the gate voltage VGE3 are not affected by the emitter electrode resistance component R 1 , the collector current Ic2 and the sense current Is do not decrease even if the collector current Ic1 decreases. 
     As a result, in the main current flowing through the IGBT in the IGBT chip  1 D, as much as a current amount of the collector current Ic1 flowing through the surface electrode remote region decreases and a ratio of the collector current Ic2 in the main current increases, detection sensitivity of the main current based on the sense current Is flowing through the current detection IGBT can be improved. 
     Regarding the effect of the fourth embodiment described above, the IGBT corresponds to the “switching element”, and the emitter electrode  3  corresponds to the “surface electrode”. Further, in a case where the original IGBTs in the IGBT chip  1 D are classified into the IGBTs  61  and  62 , the gate voltage VGE1 corresponds to the “control voltage” for the IGBT  61 , and the gate voltage VGE2 corresponds to the “control voltage” for the IGBT  62 . Furthermore, the current detection output pad  15  corresponds to the “current detection pad”, and the gate voltage VGE3 corresponds to the “control voltage” for the IGBT  63 . 
     Note that, as the semiconductor device  54  according to the fourth embodiment, a structure in which the current detection output pad  15 , the current detection element formation region  27 , and the like are added based on the embodiment  51  is described. The present invention is not limited to this structure, and a structure in which the current detection output pad  15 , the current detection element formation region  27 , and the like are added based on the semiconductor device  52  or the semiconductor device  53  may be employed as a variation. Also in a variation of the fourth embodiment, an effect unique to the fourth embodiment can be similarly exhibited. 
     Others 
     In the semiconductor devices  51  to  54  according to the first to fourth embodiments, an IGBT is used as a switching element. By using the IGBT as a switching element, an effect below is obtained. Hereinafter, the semiconductor device  51  of the first embodiment will be described as a representative. 
     The IGBT provided in the IGBT chip  1  of the semiconductor device  51  has a PN junction, and loss corresponding to rising voltage (1 VF≈0.7 V) is always generated at the time of energization. Here, “VF” means forward voltage of a diode, and loss of 1 VF occurs between the emitter electrode  3  and the collector electrode  4 . 
     For this reason, even if loss occurs due to the minute emitter electrode resistance component R 1  of the emitter electrode  3  which is a surface electrode, the above-described loss of 1 VF due to original rising voltage is dominant. Therefore, in the semiconductor device  51 , even if the emitter electrode resistance component R 1  is designed to be large, increase in loss is easily allowed, and reliability of the device can be further enhanced. 
     As described above, in a case where the IGBT is used as a switching element provided in the IGBT chip  1 , the IGBT has a characteristic that rising voltage at the time of energization is hardly affected by loss due to the emitter electrode resistance component R 1  of the emitter electrode  3 , so that the semiconductor device  51  that is highly reliable can be obtained. 
     Note that another semiconductor element such as a MOSFET may be used as switching elements other than the IGBT. As a constituent material as a MOSFET, for example, silicon (Si) or silicon carbide (SiC) can be considered. Even in this case, the effect described in the first to fourth embodiments can be exhibited. 
     Further, a switching element typified by the IGBT is generally formed of silicon (Si), but as a variation, it is conceivable to form the switching element from a wide band gap semiconductor having a band gap larger than that of silicon. Examples of the wide band gap semiconductor include silicon carbide, a gallium nitride-based material, and diamond. 
     Hereinafter, as a semiconductor device having a switching element formed from a wide band gap semiconductor, a variation of the semiconductor device  51  of the first embodiment will be described as a representative. 
     In the variation of the semiconductor device  51 , the IGBT is formed of a wide band gap semiconductor. Since the IGBT has high withstand voltage and high allowable current density, the IGBT can be downsized. Therefore, the variation of the semiconductor device  51  has an effect that downsizing of the device as a semiconductor module can be achieved as the downsized IGBT is provided in the IGBT chip  1 . 
     Further, since the wide gap semiconductor has high heat resistance, it is possible to downsize a heat dissipation fin of a heat sink and to air-cool a water-cooled portion. For this reason, in the variation of the semiconductor device  51 , it is possible to further downsize the semiconductor module. 
     As described above, the IGBT in the variation of the semiconductor device  51  is formed of the wide gap semiconductor. As described above, since the wide band gap semiconductor has characteristics of high withstand voltage, high allowable power density, and high heat resistance, downsizing of the device can be achieved in the variation of the semiconductor device  51 . 
     Furthermore, since the wide gap semiconductor has low power loss, efficiency of an IGBT element can be improved, and therefore, efficiency of the semiconductor module including the IGBT can be improved. From the characteristics of high heat resistance and low loss as described above, it is easy to allow increase in loss deterioration due to the emitter electrode resistance component R 1  of the emitter electrode  3 . 
     As described above, the variation of the semiconductor device  51  can exhibit the various effects described above. Note that the IGBT in the above-described effect corresponds to the “switching element”, the IGBT chip  1  corresponds to the “semiconductor chip”, and the emitter electrode  3  corresponds to the “surface electrode”. 
     Note that, as a matter of course, the switching elements represented by the IGBTs provided in the IGBT chips  1  and  1 B to  1 D can be applied to either a planar type or a trench type. 
     Further, in the present disclosure, the embodiments can be freely combined with each other, and each of the embodiments can be appropriately modified or omitted. 
     EXPLANATION OF REFERENCE SIGNS 
     
         
           1 ,  1 B to  1 D: IGBT chip 
           2 : control terminal 
           3 : emitter electrode 
           4 : collector electrode 
           5 ,  6 : main current wiring 
           7 ,  7 B: control wire 
           8 : gate pad 
           9 : emitter sense pad 
           10 : emitter sense wiring 
           11 : main current wiring connection region 
           12 : insulating film 
           13 : on-chip bonding material 
           14 : main current wire 
           15 : current detection output pad 
           20 ,  20 C,  20 D: ineffective region 
           27 : current detection element formation region