Abstract:
Provided is a semiconductor device having a wiring structure on a semiconductor element and capable of securing high quality and high reliability in response to the desire for high-temperature operations, a large-current specification, thinner wafers, smaller device size, and reduced loss. A semiconductor device that includes an insulating circuit board; a semiconductor element implemented on the insulating circuit board; a first insulating resin layer laminated on the insulating circuit board; a copper-plated wiring which contacts the semiconductor element via a window portion formed in the first insulating resin layer, which enables contact with the semiconductor element; and a second insulating resin layer laminated so as to seal the copper-plated wiring, and a method for producing the semiconductor device are provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from Japanese Patent Application No. 2015-105692 filed on May 25, 2015, the disclosure of which is hereby incorporated herein by reference. 
       BACKGROUND ART 
       [0002]    For wiring on device chips of power modules, conventional structures such as an aluminum wire structure and a copper wire structure or a lead frame structure in which a copper plate is bonded by using solder or a metal nanoparticle sintered compact and the like are known. 
         [0003]    Recently, it is desired that semiconductor devices operate at high temperatures, and thus, copper materials with excellent fatigue strength have been anticipated particularly as a wiring material. However, in a copper wire structure, it is difficult to feed large current due to its small wiring cross section, and also, a function for dissipating heat from device chips cannot be expected due to small heat capacity. In addition, in bonding copper wires, stress may be applied to device chips, and in bonding wires onto thin chips used to reduce device loss, the device chips may thus crack. 
         [0004]    On the other hand, in a lead frame structure which uses a Cu plate for wiring, by using a thick plate, paths for large currents can be secured and increase in the heat capacity can be anticipated. Bonding materials are necessary in this structure; however, in recently required high-temperature operations, the long-term reliability of currently used soldering materials is not sufficient. In addition, nanoparticle compacts of Ag or Cu are expensive, and also, it is difficult to ensure reliability of bonding due to possibly occurring voids. 
         [0005]    A power device module is known which is effective as a large current, high heat resistance, and high radiation wiring module (see Patent Literature 1). However, because a power device module like this uses a metal plate constituted by a material such as a Cu alloy as a lead frame material, such a power device module cannot overcome the defects of the conventional technique. In addition, in the conventional power device module, a structure in which an insulating sealing resin is arranged between metal structure layers is disclosed, however, in a structure in which an insulating sealing resin is arranged between metal structure layers only, the configuration is insufficient for protecting the devices and wiring from factors such as impact, temperature, humidity, and the like. 
         [0006]    In addition, an electronic component device has been known in which integrated circuit (IC) chips and connection electrode parts are bonded by wire bonding with gold wires and the resulting assemblies are sealed with an insulating sealing resin (see Patent Literature 2). However, an electronic component device like this cannot reduce the stress on the chips applied concurrently in operations for wire bonding. 
       BRIEF SUMMARY OF THE INVENTION 
     Technical Problem 
       [0007]    An object of the present invention is to provide a semiconductor device arranged on a wiring structure of a semiconductor element (chip) which solves the problems arising in the conventional technique and having a structure that secures a high quality and a high reliability in response to the desire for high-temperature operations, a large-current specification, thinner wafers, smaller device size, and reduced loss. 
       Solution to Problem 
       [0008]    The inventor has conceived of configuring wiring that uses a copper material on a semiconductor element without using any bonding materials such as solders, metal nanoparticles, and the like or having to perform a wire bonding process that uses ultrasonic waves, and thus has completed the present invention. 
         [0009]    According to an aspect of the present invention, a semiconductor device comprises an insulating circuit board; a semiconductor element implemented on the insulating circuit board; a first insulating resin layer laminated on the insulating circuit board; a copper-plated wiring which contacts the semiconductor element via a window portion formed on the first insulating resin layer which enables contact with the semiconductor element; and a second insulating resin layer laminated so as to seal the copper-plated wiring. 
         [0010]    In the semiconductor device, it is preferable that the copper-plated wiring be in the shape of a sheet. 
         [0011]    In the semiconductor device, it is preferable that the copper-plated wiring include a seed layer, which is a thin film layer constituted by a metal or an alloy, and a copper-plated layer laminated on the seed layer. 
         [0012]    In the semiconductor device, it is preferable that the seed layer be a metal or an alloy constituted by one or more selected from the group consisting of Cu, Ni, Al, Ag, and Au. 
         [0013]    In the semiconductor device, it is preferable that the first insulating resin layer and/or the second insulating resin layer be a resin constituted by one or more selected from the group consisting of polyamide resin, polyimide resin, epoxy resin, polyether ether ketone resin, and polybenzimidazole resin. 
         [0014]    According to another aspect of the present invention, a production method of a semiconductor device includes a process of implementing a semiconductor element on an insulating circuit board; a process of laminating a first insulating resin layer on the insulating circuit board; a process of forming a copper-plated wiring which contacts the semiconductor element via a window portion formed on the first insulating resin layer which enables contact with the semiconductor element; and a process of laminating a second insulating resin layer so as to seal the copper-plated wiring. 
         [0015]    In the semiconductor device production method, it is preferable that the process of forming the copper-plated wiring include a process of forming a seed layer that is a thin film metal or alloy layer; and a process of laminating a copper-plated wiring on the seed layer by copper plating. 
         [0016]    In the semiconductor device production method, it is preferable that the process of forming the seed layer be performed by using a sputtering method or by nonelectrolytic plating. 
         [0017]    In the semiconductor device production method, it is preferable that the process of forming the first insulating resin layer include a process of placing a resin film constituted by one or more selected from the group consisting of polyamide resin, polyimide resin, epoxy resin, polyether ether ketone resin on the insulating circuit board on which the semiconductor element is implemented, and polybenzimidazole resin; and a process of forming the first insulating resin layer so that the thickness on the semiconductor element is 20 μm or more by melting the resin film. 
       Advantageous Effects of Invention 
       [0018]    According to the semiconductor device of the present invention, an wiring that connects the semiconductor element and the insulating circuit board is a copper-plated wiring, and thereby large currents can be applied, the long-term reliability in operations at high temperatures can be improved, and the device size can be reduced. In particular, because the copper-plated wiring can connect the semiconductor element and the copper wiring on the insulating circuit board by a short distance, and thus, it is possible to reduce the switching loss that may occur due to reduction of inductance. In addition, compared with the case of using a wire-bonded lead frame or a plate lead frame, the height of the module, i.e., the dimension in a direction normal to the board surface, can be reduced, and thereby a small-size semiconductor device can be implemented. 
         [0019]    Further, according to the semiconductor device production method of the present invention, an wiring that connects the semiconductor element and the insulating circuit board can be produced by a plating method. In the bonding by this plating method, no stress is applied to the semiconductor element, and thus it is possible to use thinner wafers for semiconductor elements. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0020]      FIG. 1( a )  is a schematic cross section of a semiconductor device according to an embodiment of the present invention.  FIG. 1( b )  is an enlarged drawing of the semiconductor device illustrated in  FIG. 1( a )  in an X portion thereof. 
           [0021]      FIG. 2  is a schematic plan view of the semiconductor device illustrated in  FIG. 1 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0022]    An embodiment of the present invention will be described below with reference to attached drawings. However, the present invention is not limited to the embodiments described below. The drawings are schematic views attached for explanation of the present invention, and the dimensions of the members that constitute the device and the relative relationship among them do not limit the present invention. 
         [0023]    According to an embodiment, the present invention relates to a semiconductor device.  FIG. 1( a )  is a schematic cross section of the semiconductor device according to an embodiment of the present invention. In the semiconductor device  1  illustrated in  FIG. 1( a ) , a semiconductor element  17  is implemented on a copper wiring  14   c  that constitutes an insulating circuit board  13  via a bonding material  19 , and copper wirings  14   a,    14   b,  and  14   c  and the semiconductor element  17  are sealed with a first insulating resin layer  21 . The semiconductor element  17  and the copper wirings  14   a  and  14   b  are connected by copper-plated wirings  11   a  and  11   b,  respectively. In addition, to the copper wiring  14   a,    14   b,  an external connection terminal  12   a,    12   b  extending to an outside of the semiconductor device  1  is bonded, respectively. Also to the copper wiring  14   c,  an external connection terminal  12   c  (see  FIG. 2 ) is bonded. A second insulating resin layer  22  is laminated so as to seal the copper-plated wiring  11   a,    11   b.  On the other hand, to the metal layer  16  that constitutes the insulating circuit board  13 , a heat sink  18  is bonded via the bonding material  19 . 
         [0024]    On the insulating circuit board  13 , the copper wiring  14  (hereinbelow, the copper wirings  14   a,    14   b,  and  14   c  will be collectively referred to as the “the copper wiring  14 ”) is arranged on one surface of an insulating layer  15 , and on the other surface of the insulating layer  15 , a metal layer  16  is arranged. As an example of the above-described insulating circuit board  13 , a heat radiation insulating substrate produced by bonding a copper circuit to an alumina ceramic substrate by a direct copper bond (DCB) method can be used. However, the insulating circuit board  13  is not limited to a specific insulating circuit board and an insulating circuit board at least including an insulating layer and copper wirings can be used. 
         [0025]    The configuration of the semiconductor element  17  can be determined based on the purpose of use and the specifications of the semiconductor device  1 . Specifically, an insulated gate bipolar transistor (IGBT), a metal oxide semiconductor field-effect transistor (MOSFET), a field effect transistor (FET), a bipolar transistor, a gate turn-off thyristor (GTO), a Schottky barrier diode (SBD), a rectifying diode, and the like can be used, although this is not so limited. Examples of compounds that constitute the semiconductor element include, but are not limited to, silicon and SiC. In the semiconductor device  1  according to the present embodiment, a particularly thin semiconductor element that may easily crack can be used for the semiconductor element  17 . For example, a semiconductor element with the thickness of 30 to 450 μm can be used. For the bonding material  19 , which bonds the semiconductor element  17  to the copper wiring  14   c,  a general-purpose material such as a solder can be used. 
         [0026]    The first insulating resin layer  21 , which is laminated on the insulating circuit board  13 , covers, insulates, and seals the copper wiring  14 , the semiconductor element  17 , and the bonding material  19 . The first insulating resin layer  21  may be constituted by any resin generally used as a sealing resin and is preferably a resin with a chemical structure including one or more selected from the group consisting of a polyamide structure, polyimide structure, epoxy structure, polyether ether ketone structure, and polybenzimidazole structure, although this is not so limited. It is particularly preferable to use a resin constituted by one or more selected from the group consisting of polyamide resin, polyimide resin, epoxy resin, polyether ether ketone resin, and polybenzimidazole resin. It is more preferable to use a resin having a glass transition temperature of 150° C. or more. 
         [0027]    The copper-plated wiring  11   a,    11   b  contacts the semiconductor element  17  via a window portion, which enables contact with the semiconductor element  17  and contacts the copper wiring  14   a,    14   b  via a window portion which enables contact with the copper wiring  14   a,    14   b.  The term “window portion” herein refers to an exposed surface of an electrode formed by cutting and removing the first insulating resin layer  21 . A portion around the exposed surface is constituted by the first insulating resin layer  21 . In the semiconductor device  1  illustrated in  FIG. 1( a ) , the copper-plated wiring  11   a  which electrically connects an electrode on the semiconductor element  17  to the copper wiring  14   a  and the copper-plated wiring  11   b  which electrically connects another electrode on the semiconductor element  17  with the copper wiring  14   b  are arranged. In the embodiment illustrated in the drawing, for both the copper-plated wiring  11   a  and the copper-plated wiring  11   b,  a protruding structure (hereinafter referred to as a “protrusion”) is provided in a portion near the portion for contacting the semiconductor element  17  on an opposite side of the insulating circuit board  13 , i.e., in the upper portion of  FIG. 1 . This is intended to prevent electric breakdown that may otherwise occur when a large current is applied due to close arrangement of an end portion of the surface of the semiconductor element  17  on which the electrode is arranged and the copper-plated wiring  11 . The protrusion may be formed preferably so that the distance between a vertex of the protrusion of the copper-plated wiring  11  and the insulating circuit board  13  becomes larger than the total thickness of the thickness of the semiconductor element  17 , the thickness of the copper-plated wiring  11 , and the thickness of the bonding material  19  by 20 μm or more, and more preferably, by 50 μm or more. The shape and the location of the protrusion of the copper-plated wiring  11  described above can be specifically determined in accordance with the second process and the third process of the following the semiconductor device production method. By configuring the copper-plated wiring  11  as described above, the semiconductor element  17  and the copper wiring  14   a,    14   b  can be connected by a shorter distance compared with ordinary wiring by the conventional technique while preventing electric break at the same time. 
         [0028]      FIG. 2  is a plan view of the semiconductor device  1  illustrated in  FIG. 1 . However, the first insulating resin layer  21  and the second insulating resin layer  22  are omitted from the drawing for easier understanding of the positional relationship among the component members. Referring to  FIG. 2 , it is preferable that the copper-plated wiring  11  have a sheet-like shape. This is intended to reduce the electric resistance and enable feeding of large currents due to the large cross section obtained by the above-described configuration. Specifically, it is preferable that the copper-plated wiring  11  be sheet shaped with the thickness of 50 to 500 μm, more preferably 60 to 200 μm, for example. The thickness of the copper-plated wiring  11  can be appropriately determined by a person skilled in the art according to the function of the copper-plated wiring  11 . 
         [0029]    Next, referring to  FIG. 1( b ) , which is an enlarged drawing of an X portion of  FIG. 1( a ) , the copper-plated wiring  11   a  includes a seed layer  111 , which is a thin film metal layer or a thin film alloy layer, and a copper-plated layer  112 , which is laminated on the seed layer  111  by copper plating. It is preferable that the seed layer  111  be a metal or an alloy constituted by one or more selected from the group consisting of Cu, Ni, Al, Ag, and Au. It is preferable that the copper-plated layer  112  be constituted by copper alone or an alloy including copper. If a copper alloy is used, it is preferable that the copper alloy be an alloy constituted by copper and one or more metals selected from the group consisting of gold, silver, tin, nickel, and phosphorus. Examples of a preferable combination of the material of the seed layer  111  and the copper-plated layer  112  includes, but is not limited to, a combination of copper and copper, and a combination of nickel and copper. Although not shown in the drawing, the copper-plated wiring  11   b  also can include the same layer configuration. 
         [0030]    It is preferable that the thickness of the seed layer  111  be even generally for the entire copper-plated wiring  11   a.  For example, the thickness of the seed layer  111  may be 0.1 to 5 μm, more preferably 0.5 to 2 μm. If the seed layer  111  is too thin, microscopic defects may occur in the plating, thus power cannot be evenly applied in the electrolytic copper plating process carried out in forming the copper-plated wiring  11   a,  and as a result, the copper-plated wiring  11   a  may be unevenly plated. In contrast, if the seed layer  111  is too thick, large stress may remain on the seed layer  111  and thus the seed layer may be peeled off. In addition, time taken for forming the seed layer may become long. It is preferable that the thickness of the copper-plated layer  112  be generally even for the entire copper-plated wiring  11   a.  Specifically, the thickness of the copper-plated layer  112  may be 50 to 500 μm, preferably 60 to 200 μm, for example. If the copper-plated wiring  11   a  is too thin, necessary current cannot be applied in some cases. In contrast, if the copper-plated wiring  11   a  is too thick, large stress may remain on the copper-plated wiring and may cause peeled layer. Also in some cases, the process time may become long. 
         [0031]    The copper-plated wiring  11  preferably includes the seed layer  111  and the copper-plated layer  112  and does not include a copper plate or a copper wire. This is intended to prevent stress from being applied to the semiconductor element  17  in bonding of the copper-plated wiring  11  to the semiconductor element  17  if a copper plate or a copper wire is used as a substitute for the copper-plated wiring  11 . 
         [0032]    The semiconductor device  1  illustrated in  FIGS. 1 and 2  includes the copper-plated wiring  11   a  which connects the semiconductor element  17  and the copper wiring  14   a,  which controls ON/OFF of the current flowing between the electrodes, and the copper-plated wiring  11   b  which connects the semiconductor element  17  and the copper wiring  14   b,  which functions as a power feeding electrode. A width da of the copper-plated wiring  11   a  is preferably wider than a width db of the copper-plated wiring  11   b.  This is because a current applied through the copper-plated wiring  11   a  may be larger than the current applied through the copper-plated wiring  11   b.  However, the width da of the copper-plated wiring  11   a  and the width db of the copper-plated wiring  11   b  may be either the same as each other or different from each other in accordance with the configuration of the embodiment. Specifically, the widths can be appropriately determined by a person skilled in the art according to the size of the semiconductor chip, the amount of current to be applied, and other specifications, and are not limited to the configuration illustrated in the drawing. In addition, although not shown in the drawing, the semiconductor device according to the present invention is not limited to the configuration in which two copper-plated wirings such as the copper-plated wirings  11   a  and  11   b  are arranged. In other words, if an element such as a diode is used, a configuration can be included in which only one wiring may be arranged in an upper portion of the element. 
         [0033]    Referring to  FIG. 1  again, the second insulating resin layer  22  is laminated on members on the insulating circuit board  13  so as to cover (seal) the copper-plated wiring  11   a,    11   b.    FIG. 1  is a cross section of the device showing the portion in which the copper-plated wirings  11   a,    11   b  are arranged. In the portion in which the copper-plated wirings  11   a,    11   b  are not arranged, the second insulating resin layer  22  basically contacts the first insulating resin layer  21  and is laminated on the first insulating resin layer  21 . The second insulating resin layer  22  can be selected from the same resin as described above for the first insulating resin layer  21 . The second insulating resin layer  22  and the first insulating resin layer  21  can be constituted by the same resin or different resins. The second insulating resin layer  22  may be formed so as to have a thickness with which it can cover, insulate, and seal the semiconductor element  17 , the copper-plated wirings  11   a  and  11   b  and external connection terminals  12   a,    12   b,  and  12   c.  This thickness can be appropriately determined by a person skilled in the art. 
         [0034]    The external connection terminals  12   a,    12   b,  and  12   c  are electrically connected to the copper wirings  14   a,    14   b,  and  14   c  that constitute the insulating circuit board  13 , respectively. The external connection terminal  12  may be constituted by a copper plate or a copper alloy plate. One end of the external connection terminal  12  is bonded to the copper wiring  14  by a solder or other bonding materials. The external connection terminal  12  may be sealed by the first insulating resin layer  21 , or optionally by the first insulating resin layer  21  and the second insulating resin layer  22 . The other end of the external connection terminal  12  extends from the semiconductor device  1  outward, which enables electrical connection with an outside of the device. 
         [0035]    The heat sink  18  can be arranged in the metal layer  16 , which constitutes the insulating circuit board  13 , via the bonding material  19 . The heat sink  18  may be a copper plate or an aluminum fin, and the shape of the heat sink  18  is not limited to the shape shown in the drawing. 
         [0036]    In the semiconductor device having the above-described configuration, large currents can be applied due to the copper-plated wirings and the semiconductor element can be made thin Accordingly, the size of the device can be designed smaller compared with the conventional technique. For example, the area of the insulating circuit board can be reduced to about 70 to 90% of that of the conventional device. In addition, the height of the semiconductor device can be reduced to 40 to 70% of the conventional device. 
         [0037]    Next, the present invention will be described from the viewpoint of the method of producing the semiconductor device. The semiconductor device production method according to an embodiment of the present invention includes a first process of implementing the semiconductor element to the insulating circuit board; a second process of laminating the first insulating resin layer on the insulating circuit board; a third process of forming a copper-plated wiring which contacts the semiconductor element via a window portion which enables contact with the semiconductor element; and a fourth process of laminating the second insulating resin layer so as to seal the copper-plated wiring. The semiconductor device production method according to the present embodiment will be described below with reference to  FIGS. 1 and 2  again. 
         [0038]    In the first process of implementing the semiconductor element  17  on the insulating circuit board  13 , the insulating circuit board  13  constituted by the insulating layer  15  which includes the copper wiring  14  on one surface thereof and the metal layer  16  on the other surface thereof is prepared, and the semiconductor element  17  is implemented on the copper wiring  14   c  (a die pad portion) by using the bonding material  19  such as a solder. The above-described process can be implemented by a technique usually used in general semiconductor device production methods. 
         [0039]    In the second process of laminating the first insulating resin layer  21  on the insulating circuit board  13 , the first insulating resin layer  21  is laminated on the surface of the insulating circuit board  13  obtained in the first process, on which the semiconductor element  17  has been implemented, on the side of the copper wiring  14 . To form the first insulating resin layer  21 , optionally one sheet or more laminated sheets of a resin film constituted by a resin preferably including one or more selected from the group consisting of polyimide resin, epoxy resin, polyether ether ketone resin, and polybenzimidazole resin can be placed on the insulating circuit board  13  where necessary. In a more preferred embodiment, in the second process, a resin film is placed on the semiconductor element  17  so that a first insulating resin layer with the thickness of 20 μm or more, more preferably 50 μm or more, is formed. This is intended to prevent electric break that may occur due to concentration of current in the protrusion of the copper-plated wiring  11  formed in the subsequent process when the semiconductor device  1  is used. The thickness of a portion of the first insulating resin layer  21  in which the semiconductor element  17  is not implemented is not particularly limited, and the thickness can be appropriately determined by a person skilled in the art so that the copper wiring  14  can be sealed and the plated wiring formed in the next process can be arranged in a portion with a desired distance from the insulating circuit board  13 . For example, the first insulating resin layer  21  can be formed to the same height of the first insulating resin layer  21  on the semiconductor element  17  for the entire surface of the insulating circuit board  13 . In an alternative configuration, the first insulating resin layer  21  may be formed so that the thickness thereof in a portion near the semiconductor element  17  becomes thick and so that the thickness thereof becomes thinner toward the peripheral portion of the insulating circuit board  13 . 
         [0040]    For a specific operation method performed for forming the first insulating resin layer  21 , for example, a frame such as a plastic frame that surrounds the periphery of the insulating circuit board  13  is installed, and a necessary number of resin films are laminated and placed on the insulating circuit board  13 . Then the resin films are heated to a predetermined temperature determined according to the type of the resin to melt the resin film. The resin film can be cured on the insulating circuit board  13  by thermal pressure welding so that it may be closely attached. Note that the above-described values of 20 μm or more and 50 μm or more refer to the thickness of the first insulating resin layer  21  after it is heated and cured. By performing the operation described above, the copper wiring  14  on the insulating layer  15  and the semiconductor element  17  can be brought into contact with the first insulating resin layer and can be insulated and sealed by the first insulating resin layer  21 . 
         [0041]    The second process is not limited to the operation that uses the resin film. Specifically, the second process can be implemented by a method in which a resin fluidized at a predetermined temperature is applied into the insulating circuit board  13  surrounded by a frame and cured by heating therein. In this configuration, it is preferable to implement the second process so that the first insulating resin layer  21  having the above-described predetermined thickness or thicker is laminated on the semiconductor element  17 . 
         [0042]    Then, in the third process of forming the copper-plated wiring  11  which contacts the semiconductor element  17  via the window portion which enables contact with the semiconductor element  17 , the window portion is formed in the first insulating resin layer  21  and the copper-plated wiring  11  is formed. With respect to the window portion, in the embodiment illustrated in the drawing, one window portion is arranged to each of the two electrodes located on the surface of the semiconductor element  17  opposite to the bonding material  19 , one window portion is arranged on the copper wiring (electrode)  14   b  which has a function of a power feeding electrode, and one window portion is arranged on the copper wiring (electrode)  14   a  which has a function of controlling ON/OFF of the current applied between the electrodes. Specifically, the window portion can be implemented by cutting to remove the first insulating resin layer  21  which covers a desired electrode with a laser, for example. By performing the operation described above, the window portion in which the electrode surface is exposed and which enables electrical connection with the copper-plated wiring  11  can be formed. The size of the window portion can be appropriately determined by a person skilled in the art in accordance with the amount of necessary current. 
         [0043]    More specifically, the copper-plated wiring  11  can be formed by performing a method including a process of forming the seed layer  111 ; a process of forming a mask in a portion other than a portion including the wirings; a process of forming the thick copper-plated layer  112 ; and a process of removing the mask and the seed layer. In the process of forming the seed layer  111 , a metal layer of an alloy layer constituted by one or more selected from the group consisting of Cu, Ni, Al, Ag, and Au is formed on the entire surface of the members on the insulating circuit board  13  including the first insulating resin layer  21  and the window portion by a sputtering method or an nonelectrolytic plating method. The thickness of the layer is as described above in the embodiment of the semiconductor device  1  as an example. In the process of forming the mask in the portion other than the portion in which the copper-plated wiring  11  is arranged, the mask is formed on a portion of the first insulating resin layer  21  and the window portion in which the copper-plated wiring  11  is not formed. For the mask, a resin mask can be appropriately used, and the mask can be formed by generally used mask forming methods. By adjusting the portion (area) for forming the mask in this process, the width of the copper-plated wiring  11  can be determined For example, as illustrated in  FIG. 2 , the width da of the copper-plated wiring  11   a  and the width db of the copper-plated wiring  11   b  can be easily assigned with mutually different values by performing this process. 
         [0044]    In the subsequent process of forming the thick copper-plated layer  112 , a thick plated layer is formed by electrolytic copper plating. The composition of the plating bath and the plating conditions may be those used in general electrolytic copper plating, and can be appropriately determined by a person skilled in the art. For example, to form a plated layer plated with copper alone and having a thickness of about 60 to 80 μm, the current density may be 1 to 15 A/dm2. 
         [0045]    In the process of removing the mask and the seed layer, the mask can be removed by a method suitable for removal of the mask used. The seed layer can be removed by etching that uses an etching liquid selected according to the components of the seed layer. By performing this third process, the copper-plated wiring  11  including the seed layer  111 , which is a thin film metal layer or a thin film alloy layer, and the copper-plated layer  112 , which is laminated on the seed layer, can be formed at a desired location. 
         [0046]    After the third process and before the fourth process, a process of attaching parts such as external connection terminals can be implemented as an optional process. For example, for the external connection terminal  12   a,    12   b,    12   c  illustrated in  FIG. 2 , the first insulating resin layer  21  is cut, thus the window portions are formed at predetermined locations of the copper wirings  14   a,    14   b,    14   c,  and the external connection terminals  12   a,    12   b,    12   c  constituted by copper plates prepared by conventional techniques can be bonded by using a solder or other bonding materials. In addition, coupling by screwing (not illustrated) can be formed. 
         [0047]    In the fourth process of laminating the second insulating resin layer  22  so as to seal the copper-plated wiring  11 , the second insulating resin layer is laminated on the members on the insulating circuit board  13  obtained by the third process or by the subsequent optional process. Generally, the second insulating resin layer  22  is laminated so as to cover the first insulating resin layer  21 , which has been located on the most front surface after the removal of the mask and the seed layer therefrom, and the copper-plated wiring  11 . Specifically, the fourth process can be implemented by a method including an operation in which, similarly to the second process, the insulating circuit board  13  is surrounded with a frame; a resin film is placed on the members on the insulating circuit board  13 ; and the resin film is heated to a predetermined temperature or a previously heated fluidized resin is applied to the insulating circuit board  13  and cured by heating. In this configuration, if a window portion formed by the optional process is arranged, for example, the second insulating resin layer  22  is also applied to the periphery of the external connection terminals  12   a,    12   b,    12   c  constituted by the window portion and the plate, which thereby enables sealing of the window portion and the external connection terminals  12   a,    12   b,    12   c.    
         [0048]    According to the semiconductor device production method of the present embodiment, the copper-plated wiring can be formed without using a bonding material and without using ultrasonic wave bonding, which applies stress to the chip. The above-described production method is advantageous in that specifications of the sheet-like copper-plated wiring such as the width and the thickness can be easily changed. 
       INDUSTRIAL APPLICABILITY 
       [0049]    The semiconductor device according to the present invention can be preferably used as a power module for feeding large currents, and the like. 
       REFERENCE SIGNS LIST 
       [0050]      1  Semiconductor device 
         [0051]      11   a,    11   b  Copper-plated wiring 
         [0052]      111  Seed layer 
         [0053]      112  Copper-plated layer 
         [0054]      12   a,    12   b,    12   c  External connection terminal 
         [0055]      13  Insulating circuit board 
         [0056]      14   a,    14   b,    14   c  Copper wiring 
         [0057]      15  Insulating layer 
         [0058]      16  Metal layer 
         [0059]      17  Semiconductor element (chip) 
         [0060]      18  Heat sink 
         [0061]      19  Bonding layer 
         [0062]      21  First insulating resin layer 
         [0063]      22  Second insulating resin layer