Patent Publication Number: US-2015069598-A1

Title: Heat dissipation connector and method of manufacturing same, semiconductor device and method of manufacturing same, and semiconductor manufacturing apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2013-185635, filed on Sep. 6, 2013, the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate to a heat dissipation connector and a method of manufacturing the same, a semiconductor device and a method of manufacturing the same, and a semiconductor manufacturing apparatus. 
     BACKGROUND 
     A semiconductor chip, which generates a great deal of heat, is sealed up with a molding resin along with a heat dissipation disk for releasing the heat from the semiconductor chip. The heat dissipation disk is stacked on the semiconductor chip via a connector component, and the upper face of the heat dissipation disk is exposed out of the molding resin. 
     If the semiconductor chip is reduced in size in order to miniaturize a semiconductor device, the connector component and the heat dissipation disk also need to be reduced in size correspondingly to the size of the semiconductor chip. However, it is increasingly difficult to precisely stack the heat dissipation disk on the connector component if the connector component is made smaller. This may reduce the manufacturing yield of the semiconductor device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are drawings of a semiconductor device of a first embodiment; 
         FIGS. 2A and 2B  are drawings of a heat dissipation connector of the first embodiment; 
         FIGS. 3A to 3C  are drawings for describing a method of manufacturing the heat dissipation connector of the first embodiment; 
         FIG. 4  is a flowchart showing a method of manufacturing the semiconductor device of the first embodiment; 
         FIG. 5  is a schematic view of a semiconductor manufacturing apparatus of the first embodiment; 
         FIGS. 6A and 6B  are drawings of a heat dissipation connector of a modified example of the first embodiment; 
         FIGS. 7A and 7B  are drawings of a heat dissipation connector of a second embodiment; 
         FIGS. 8A to 8C  are drawings for describing a method of manufacturing the heat dissipation connector of the second embodiment; and 
         FIGS. 9A and 9B  are drawings of a heat dissipation connector of a modified example of the second embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments will now be explained with reference to the accompanying drawings. The present invention is not limited to these embodiments. Common components are denoted by common reference numerals throughout the drawings, and duplicate descriptions of these components are omitted. The drawings are schematic views used to facilitate the description and understanding of the invention, and may therefore differ from actual devices in shape, dimension, ratio and the like in some places. Design changes can be made to these devices as appropriate by taking into consideration the following description and known technology. In the following embodiments, a vertical direction of a semiconductor chip indicates a relative direction when a surface of the semiconductor chip where semiconductor elements are arranged is faced up, and may therefore differ from a vertical direction based on the gravitational acceleration in some cases. 
     In one embodiment, a heat dissipation connector mounted on a semiconductor chip and sealed up with a molding resin along with the semiconductor chip and a lead frame includes a heat dissipation portion configured to have a block shape, and have an upper face exposed out of the molding resin. The connector further includes a connecting portion configured to extend from a first side face of the heat dissipation portion, and electrically connect an electrode arranged on the semiconductor chip to the lead frame. The heat dissipation portion and the connecting portion are integrally made of the same metal sheet. 
     First Embodiment 
       FIGS. 1A and 1B  are drawings of a semiconductor device  10  of a first embodiment. 
       FIG. 1A  illustrates a cross section of the semiconductor device  10  of the first embodiment, and  FIG. 1B  illustrates an upper face of the semiconductor device  10 . In  FIG. 1B , a molding resin  19  is omitted from the illustration for the sake of clarity. 
     The semiconductor device  10  includes a lead frame  11 , a semiconductor chip  13 , a connector  16 , a heat dissipation connector  18 , and the molding resin  19 . 
     The molding resin  19  seals up the lead frame  11 , the semiconductor chip  13 , the connector  16 , and the heat dissipation connector  18 . An upper face  681  of the heat dissipation connector  18  is exposed out of the molding resin  19 . 
     The lead frame  11  includes an island portion  12 , and a first and second terminal portions  111  and  112  which are separated from the island portion  12 . The lead frame  11  is made of an electrical conductor and formed with, for example, low-resistance metal. The island portion  12  is a mounting portion on which the semiconductor chip  13  is mounted. The first terminal portion  111  and the second terminal portion  112  are electrically connected to the first electrode  131  and the second electrode  132  of the semiconductor chip  13 . 
     The semiconductor chip  13  is mounted on the island portion  12  and includes the first electrode  131  and the second electrode  132 . The type of semiconductor chip  13  is optional, and therefore is not limited in particular. 
     The connector  16  is located on the second electrode  132  and the second terminal portion  112  in order to electrically connect the second electrode  132  and the second terminal portion  112 . The connector  16  is also made of an electrical conductor and formed with, for example, low-resistance metal. 
     The heat dissipation connector  18  is located on the first electrode  131  of the semiconductor chip  13  and the first terminal portion  111  in order to electrically connect the first electrode  131  and the first terminal portion  111 . The heat dissipation connector  18  is formed of metal (for example, copper) having excellent electrical conductivity and thermal conductivity. Accordingly, this heat dissipation connector  18  has the function of not only discharging heat from the semiconductor chip  13  to outside the semiconductor device  10  but also electrically connecting the first electrode  131  and the first terminal portion  111 . 
       FIGS. 2A and 2B  are drawings of the heat dissipation connector  18  of the first embodiment. 
       FIG. 2A  illustrates a cross section of the heat dissipation connector  18 , and  FIG. 2B  illustrates an upper face of the heat dissipation connector  18 . 
     The heat dissipation connector  18  includes a heat dissipation portion  181  for discharging heat, and a connecting portion  182  for electrically connecting the first electrode  131  and the first terminal portion  111 . The heat dissipation portion  181  and the connecting portion  182  are integrally formed of a metal sheet. That is, the heat dissipation portion  181  and the connecting portion  182  in the first embodiment are not individually formed as two separate components but are integrally formed as one heat dissipation connector  18 . 
     In addition, the heat dissipation portion  181  has a block shape. In the semiconductor device  10 , the upper face  681  of the heat dissipation portion  181  is exposed out of the molding resin  19 , and the heat of the semiconductor chip  13  is discharged to outside the semiconductor device  10  from this surface (see  FIG. 1A ). 
     The connecting portion  182  is a sheet-like portion extending from a side face  481  of the heat dissipation portion  181 , and a part of the connecting portion  182  is bent. In the semiconductor device  10 , the connecting portion  182  extends up to the first terminal portion  111  to electrically connect the first electrode  131  and the first terminal portion  111  (see  FIG. 1A ). 
     The heat dissipation portion  181  includes a side face  482  located on an opposite side of the side face  481 . The side face  482  has a step ST, and a lower region of the side face  482  (which is on the semiconductor chip  13  side) is recessed inward compared with an upper region of the side face  482  (see  FIG. 1A ). That is, the step ST is provided in a lower end portion of the side face  482  which is on the semiconductor chip  13  side. In addition, two side faces of the heat dissipation portion  181  other than the side face  481  have steps ST, as similar to the side face  482 . Accordingly, a lower face  682  (a surface in contact with the semiconductor chip  13 ) of the heat dissipation portion  181  is narrower than the upper face  681  of the heat dissipation portion  181 , and narrower than the semiconductor chip  13  as well. 
     As described above, the heat dissipation portion  181  and the connecting portion  182  in the first embodiment are integrated with each other to form one heat dissipation connector  18 . Accordingly, if the heat dissipation connector  18  can be located on the semiconductor chip  13  and the first terminal portion  111  so as to electrically connect the first electrode  131  and the first terminal portion  111 , the position of the heat dissipation portion  181  fixes for itself. The heat dissipation portion  181  therefore does not become displaced from the connecting portion  182 . Consequently, it is possible to prevent a short circuit between the heat dissipation portion  181  and another connector (for example, the connector  16 ) and improve the manufacturing yield of the semiconductor device  10 . 
     If it is assumed that the heat dissipation portion  181  and the connecting portion  182  are two separate components, it is necessary in the steps of manufacturing the semiconductor device  10  not only to locate the connecting portion  182  on the semiconductor chip  13  and the first terminal portion  111 , but also to stack the heat dissipation portion  181  on the connecting portion  182 . In addition, if the connecting portion  182  is reduced in size, it is increasingly difficult to precisely locate the heat dissipation portion  181  on the connecting portion  182 . If the heat dissipation portion  181  is stacked on the connecting portion  182  in a position displaced from a correct position of the heat dissipation portion  181 , the heat dissipation portion  181  may come into contact with other connectors and cause a short-circuit. It is therefore conceivable to make the heat dissipation portion  181  smaller so as to avoid contact with other connectors even if the heat dissipation portion  181  becomes displaced. However, the heat dissipation efficiency of the heat dissipation portion  181  decreases if the heat dissipation portion  181  is made smaller. 
     On the other hand, according to the first embodiment, the heat dissipation portion  181  and the connecting portion  182  are integrated with each other, and therefore the heat dissipation portion  181  needs not to be aligned with the connecting portion  182 . In addition, the heat dissipation portion  181  needs not to be made smaller. Consequently, it is possible to improve the manufacturing yield of the semiconductor device  10  and the heat dissipation efficiency of heat dissipation portion  181 . 
     In addition, the heat dissipation connector  18  of the first embodiment includes the step ST in the side face  482 . Consequently, when the heat dissipation connector  18  is stacked on the semiconductor chip  13 , a space (gap or trench) is formed in a part of the outer edge of the lower face  682  of the heat dissipation connector  18  by the step ST of the side face  482  and a surface of the semiconductor chip  13 . When the heat dissipation connector  18  is bonded to the semiconductor chip  13  by using a conductive adhesive agent such as solder, the excessive conductive adhesive agent stays in this space due to the effect of, for example, capillary force. Accordingly, it is possible to prevent the conductive adhesive agent from spreading outside the semiconductor chip  13 . 
     If any excessive conductive adhesive agent protrudes out of the semiconductor chip  13  and spreads up to the lead frame  11 , a short-circuit may be generated between the semiconductor chip  13  and the lead frame  11  via the conductive adhesive agent. 
     However, it is possible in the first embodiment to prevent such a malfunction by providing the step ST in the side face  482  of the heat dissipation portion  181 . The effect of the step ST of the side face  482  holds true for steps ST provided on other side faces as well. 
     (1) Method of Manufacturing Heat Dissipation Connector 
       FIGS. 3A to 3C  are drawings for describing a method of manufacturing the heat dissipation connector  18  of the first embodiment. 
       FIGS. 3A to 3C  are cross-sectional views in respective steps of the method of manufacturing the heat dissipation connector  18 . 
     As illustrated in  FIG. 3A , a metal sheet  40  is prepared. Continuous heat dissipation connectors  18  as illustrated in  FIG. 3B  are then formed by pressing a metal mold against the metal sheet  40 . 
     The heat dissipation connectors  18  are then cut apart as illustrated in  FIG. 3C . The heat dissipation connector  18  described above can be obtained in this way. 
     The continuous heat dissipation connectors  18  may be formed by pushing the metal sheet  40  between two rolls with trenches opened on their surfaces, instead of pressing the metal mold against the metal sheet  40 . 
     (2) Method of Manufacturing Semiconductor Device 
       FIG. 4  is a flowchart showing a method of manufacturing the semiconductor device  10  of the first embodiment. 
     In step S 1 , the semiconductor chip  13  is mounted on the island portion  12  of the lead frame  11  by using a conductive adhesive agent such as solder. 
     In step S 2 , the heat dissipation connector  18  is mounted on the first electrode  131  of the semiconductor chip  13  and on the first terminal portion  111  of the lead frame  11  by using a conductive adhesive agent. As described above, the heat dissipation portion  181  and the connecting portion  182  in the first embodiment are integrated with each other and formed into one heat dissipation connector  18 . Accordingly, if the heat dissipation connector  18  can be located on the semiconductor chip  13  and the lead frame  11  so as to electrically connect the first electrode  131  and the first terminal portion  111 , the heat dissipation portion  181  does not become displaced from the connecting portion  182 . In addition, since the step ST is provided on the side face  482  of the heat dissipation connector  18  as described above, the excessive conductive adhesive agent can be retained in a space formed with the step ST when the heat dissipation connector  18  is stacked on the semiconductor chip  13  by using the conductive adhesive agent. 
     In step S 3 , the connector  16  is mounted on the second electrode  132  and the second terminal portion  112  by using a conductive adhesive agent. 
     In step S 4 , the lead frame  11 , the semiconductor chip  13 , the connector  16 , and the heat dissipation connector  18  are sealed up with the molding resin  19 . At this time, these components are sealed up so as to expose the upper face  681  of the heat dissipation portion  181  out of the molding resin  19 , thereby making it possible to discharge the heat from the semiconductor chip  13  out of the semiconductor device  10  via the upper face  681 . In addition, the excessive molding resin  19  is removed. 
     In step S 5 , portions of the island portion  12  and the first and second terminal portions  111  and  112  which are exposed out of the molding resin  19  are metal-plated. 
     In step S 6 , a plurality of semiconductor devices  10  coupled by the lead frame  11  are cut apart (divided into individual pieces). 
     Consequently, the respective semiconductor devices  10  are completed. 
     According to the first embodiment, the heat dissipation portion  181  and the connecting portion  182  are integrated with each other to configure one heat dissipation connector  18 . For this reason, when the heat dissipation connector  18  is mounted on the semiconductor chip  13  and the lead frame  11 , it is sufficient to arrange the heat dissipation connector  18  so that the connecting portion  182  electrically connects the first electrode  131  and the first terminal portion  111 , and it is not necessary to align the heat dissipation portion  181  with the connecting portion  182 . It is therefore possible to improve the manufacturing yield of the semiconductor device  10 . 
     In addition, according to the first embodiment, the step ST is provided on the side face  482  of the heat dissipation connector  18 . Therefore, the excessive conductive adhesive agent can be retained in a space formed by the step ST when the heat dissipation connector  18  is stacked on the semiconductor chip  13 . Accordingly, possible malfunctions can be prevented even if the conductive adhesive agent is oversupplied. 
     (3) Semiconductor Manufacturing Apparatus 
       FIG. 5  is a schematic view of a semiconductor manufacturing apparatus  80  of the first embodiment. The semiconductor manufacturing apparatus  80  is used to mount the heat dissipation connector  18  on the semiconductor chip  13  and the lead frame  11  in step S 2  discussed above. 
     The semiconductor manufacturing apparatus  80  includes a stage  81  for holding the lead frame  11  mounted with the semiconductor chip  13 , and a transfer module  82  for adsorbing the heat dissipation connector  18  to transfer the heat dissipation connector  18  onto the semiconductor chip  13 . 
     The transfer module  82  has an adsorbing surface  821  for adsorbing the heat dissipation connector  18 . A plurality of guides  84  for guiding the heat dissipation connector  18  to a predetermined position on the adsorbing surface  821  are arranged on the adsorbing surface  821 . The plurality of guides  84  are configured to guide the heat dissipation portion  181  of the heat dissipation connector  18  to the adsorbing surface  821 , and the adsorbing surface  821  adsorbs the heat dissipation portion  181  guided by the plurality of guides  84 . In this way, the transfer module  82  can hold the heat dissipation connector  18  in the predetermined position on the adsorbing surface  821 . 
     In addition, since the heat dissipation connector  18  can be held in the predetermined position, the transfer module  82  can precisely mount the heat dissipation connector  18  on the semiconductor chip  13  and the lead frame  11  which are placed on the stage  81 . That is, the transfer module  82  can locate the heat dissipation connector  18  on the semiconductor chip  13  and the lead frame  11  so that the connecting portion  182  electrically connects the first electrode  131  and the first terminal portion  111 . 
     In this way, the heat dissipation connector  18  can be precisely mounted on the semiconductor chip  13  and the lead frame  11  by using the semiconductor device  80 . Consequently, the heat dissipation portion  181  can be located in a desired position. It is therefore possible to improve the manufacturing yield of the semiconductor device  10 . 
     (4) Modified Example 
       FIGS. 6A and 6B  are drawings of a heat dissipation connector  48  of a modified example of the first embodiment. 
       FIG. 6A  illustrates a cross section of the heat dissipation connector  48  as the modified example of the first embodiment, and  FIG. 6B  illustrates the upper face of the heat dissipation connector  48 . 
     The connecting portion  882  of the heat dissipation connector  48  is a sheet-like portion extending from the side face  781  of the heat dissipation portion  881 . Unlike the connecting portion in the first embodiment, the connecting portion  882  is a flat, belt-like sheet having no bent portion. The connecting portion  882  of the modified example can be formed by simultaneously pressing a metal sheet from its upper and lower faces and thereby thinning a part of the metal sheet. 
     The connecting portion  182  of the first embodiment is formed by bending a part of the metal sheet  40  (see  FIGS. 2 and 3 ). Since it is difficult to precisely bend the metal sheet  40  so as to form a step having a small difference of elevation, a step having a large difference of elevation is formed in the connecting portion  182  of the first embodiment. Accordingly, the upper face of the connecting portion  182  is elevated with respect to the lower face of the heat dissipation connector  18 . That is, it is difficult in the first embodiment to suppress the elevation of the upper face of the connecting portion  182 . 
     In contrast, the connecting portion  882  in the modified example is formed by not bending but thinning the part of the connecting portion  882 . Accordingly, the upper face  981  of the connecting portion  882  is not significantly elevated with respect to the lower face of the heat dissipation connector  48  as compared with the first embodiment. Consequently, it is possible to suppress the elevation of the upper face  981  of the connecting portion  882 . 
     A decrease in height of the upper face  981  of the connecting portion  882  results in a reduction in height variation of the upper face  981  of the connecting portion  882 . Consequently, it is possible to precisely form the heat dissipation connector  48  having a desired shape of the connecting portion  882 . 
     Second Embodiment 
       FIGS. 7A and 7B  are drawings of a heat dissipation connector  28  of a second embodiment. 
       FIG. 7A  illustrates a cross section of the heat dissipation connector  28  of the second embodiment, and  FIG. 7B  illustrates the upper face of the heat dissipation connector  28  of the second embodiment. 
     The heat dissipation connector  28  of the second embodiment differs from the heat dissipation connector of the first embodiment. The heat dissipation connector  28  is made of two different components, i.e., a metal sheet  50  and a metal-plated layer  51 . In the second embodiment, the metal-plated layer  51  is formed by means of metal plating. Metal plating allows the thickness of the metal-plated layer  51  to be varied easily. Accordingly, it is possible to form the metal-plated layer  51  having an appropriate thickness on a product-by-product basis. The rest of the configuration of the second embodiment may be the same as the corresponding configuration of the first embodiment. 
     In addition, the metal sheet  50  and the metal-plated layer  51  are formed of the same metal (for example, copper). In this way, bondability between the metal sheet  50  and the metal-plated layer  51  is enhanced by forming the metal sheet  50  and the metal-plated layer  51  of the same metal. It is therefore possible to efficiently transfer heat from the metal sheet  50  to the metal-plated layer  51 . Accordingly, the heat dissipation efficiency of the heat dissipation connector  28  is maintained satisfactorily, even though the heat dissipation connector  28  is made of two components. 
     (1) Method of Manufacturing Heat Dissipation Connector 
       FIGS. 8A to 8C  are drawings for describing a method of manufacturing the heat dissipation connector  28  of the second embodiment. 
       FIGS. 8A to 8C  are cross-sectional views in respective steps of the method of manufacturing the heat dissipation connector  28 . 
     First, a mask for covering regions which serve as connecting portions  282  and exposing regions which serve as heat dissipation portions  281  is formed on a metal sheet  50 . Next, metal plating is selectively performed, by using the mask, on the regions which serve as the heat dissipation portions  281  of the metal sheet  50  to form metal-plated layers  51 . The mask is then removed, so that the structure illustrated in  FIG. 8A  can be obtained. 
     Parts of the metal sheet  50  are then pressed to form continuous heat dissipation connectors  28  as illustrated in  FIG. 8B . 
     As illustrated in  FIG. 8C , the heat dissipation connectors  28  are then cut apart. The heat dissipation connector  28  of the second embodiment can be obtained in this way. 
     According to the second embodiment, the metal-plated layer  51  of the heat dissipation connector  28  is formed by means of metal plating. Consequently, it is possible to easily form the metal-plated layer  51  having an appropriate thickness on a product-by-product basis. In addition, according to the second embodiment, the metal sheet  50  and the metal-plated layer  51  are formed of the same metal. Consequently, bondability between the metal sheet  50  and the metal-plated layer  51  is enhanced to maintain excellent thermal conduction from the metal sheet  50  to the metal-plated layer  51 . 
     According to the second embodiment, the heat dissipation portion  281  and the connecting portion  282  are integrated with each other to configure one heat dissipation connector  28 , as similar to the first embodiment. It is therefore possible to obtain the same effects as those of the first embodiment. 
     (2) Modified Example 
       FIGS. 9A and 913  are drawings of a heat dissipation connector  38  of a modified example of the second embodiment. 
       FIG. 9A  illustrates a cross section of the heat dissipation connector  38  as the modified example of the second embodiment, and  FIG. 9B  illustrates the upper face of the heat dissipation connector  38 . 
     In the heat dissipation connector  38 , a metal-plated layer  61  is also formed on a portion serving as a connecting portion  382 . Accordingly, the connecting portion  382  is formed to be thicker than the connecting portion  282  of the second embodiment. The connecting portion  382  of the modified example is wider in cross-sectional area than the connecting portion  282  of the second embodiment and has excellent conductive properties. Consequently, according to the modified example, the connecting portion  382  allows the first electrode  131  and the first terminal  111  to be electrically connected with low resistance. 
     The heat dissipation connector  38  of the modified example can be formed by metal-plating the entire surface of the metal sheet  50  once, and then forming a mask on it to metal-plate again in the manufacturing method of the second embodiment. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel connectors, methods, devices and apparatuses described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the connectors, methods, devices and apparatuses described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.