Abstract:
A semiconductor chip package is formed by a first semiconductor chip and a second semiconductor chip, which have electrodes for wiring at surfaces thereof, being integrated and mounted in a state in which reverse surfaces thereof oppose one another. Therefore, two semiconductor chips can be freely combined and mounted regardless of chip sizes thereof, and lengths of wires can be shortened. Thus, a wire-bonding yield can be improved, and a semiconductor package having excellent electric characteristics can be obtained.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a semiconductor chip package in which two semiconductor chips are integrated and mounted.  
         [0003]     2. Description of the Related Art  
         [0004]     Various conventional semiconductor chip packages in which two semiconductor chips are integrated and mounted have been proposed. One example thereof is the BGA (ball grid array) type semiconductor chip package whose cross-sectional structure is illustrated in  FIG. 10 .  
         [0005]     In the case of the semiconductor package structure shown in  FIG. 10 , electrodes  58  for wiring are aligned on the center of the surface of an upper chip  52 . An example of a structure using such an arrangement is a memory LSI. On the other hand, as shown in  FIG. 12 , electrodes  56  for wiring are aligned in vicinities of each side on the surface of a lower chip  50 . An example of a structure using such an arrangement is a logic LSI such as a microcomputer or the like.  
         [0006]     The upper chip  52  and the lower chip  50  have been diced and separated into desired sizes. The lower chip  50  is fixed onto a chip mounting position of an interposer  54  formed from a material such as tape or glass epoxy by an adhesive  66  such as an epoxy resin. The upper chip  52  is similarly fixed onto the lower chip  50  by an adhesive  18 .  FIG. 13  is a schematic plan view showing a state in which the upper and lower chips have been mounted.  
         [0007]     Thereafter, the electrodes  58 ,  56  for wiring of the upper chip  52  and the lower chip  50 , respectively, are wire bonded to inner leads  64  on the interposer  54  by wire materials  62 ,  60  such as metal wires or the like. Then, the structure is resin sealed by a resin sealing material  68  formed from an epoxy resin or the like by a transfer molding method or the like. Finally, solder balls  70  are mounted at outer lead portions of the reverse surface of the interposer, and packaging is completed.  
         [0008]     However, this semiconductor chip package, in which two semiconductor chips are integrated and mounted, has the following problems. (1) As can be understood from  FIGS. 10 and 13 , when the upper chip is integrated on the lower chip, the electrodes for wiring of the lower chip are completely exposed. Further, the present structure cannot be used if the upper chip is not small enough to expose a portion of the surface of the lower chip of a surface area sufficient for carrying out wire bonding by wire materials. (2) The electrodes for wiring can be disposed either in the center of the upper chip or in the vicinities of the respective sides of the upper chip. However, at the lower chip, which must be larger than the upper chip, the electrodes for wiring must be aligned at vicinities of the respective sides, and cannot be aligned in the center. (3) When the electrodes for wiring of the upper chip are aligned in the center of the chip, the wires become long. Thus, problems arise in that there is the concern that short circuits may arise between the wires, and in that the yield is low.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention overcomes all of the aforementioned problems of the conventional art, and has as objects the following. Namely, a first object of the present invention is to provide a semiconductor chip package in which it is possible to mount two semiconductor chips freely in combination without the chip sizes being restricted. A second object of the present invention is to provide a semiconductor chip package which can be designed such that the lengths of wires are short, and thus has a stable wire bonding yield and has excellent electric characteristics.  
         [0010]     The above objects are achieved by the following means.  
         [0011]     Namely, the semiconductor chip package of the present invention comprises: a first semiconductor chip on whose surface an electrode for wiring is formed; and a second semiconductor chip on whose surface an electrode for wiring is formed, and which is integrated and mounted with the first semiconductor chip, wherein the first semiconductor chip and the second semiconductor chip are integrated and mounted with respective reverse surfaces of the first semiconductor chip and the second semiconductor chip opposing one another.  
         [0012]     In the semiconductor chip package of the present invention, because the first semiconductor chip and the second semiconductor chip are integrated and mounted with the reverse surfaces thereof facing each other, the surfaces of the first semiconductor chip and the second semiconductor chip, at which surfaces the electrodes for wiring are provided, exist at respectively different surfaces. Therefore, two semiconductor chips, whose chip sizes, positions of electrodes for wiring, and the like are different or the same can be freely combined and mounted. Namely, there are no limitations on the types of the upper and lower chips. Further, at both of the upper and lower chips, the electrodes for wiring can be disposed at the chip edge peripheries. Even if the electrodes for wiring are aligned on the center of the chip, designing can be carried out such that the lengths of wires are short. Therefore, a stable wire-bonding yield can be obtained, and further, there are advantages with regard to the electrical characteristics, such as high speed signal transmission and the like.  
         [0013]     In the semiconductor chip package of the present invention, specifically, the structures described in following &lt;1&gt; through &lt;3&gt; are suited for the structure in which the first semiconductor chip and the second semiconductor chip are integrated and mounted with the reverse surfaces thereof facing each other.  
         [0014]     &lt;1&gt; A semiconductor chip package further comprising: an interposer in which a through hole is formed at a position corresponding to the electrode for wiring on the second semiconductor chip, wherein the second semiconductor chip is fixed to a surface of the interposer at a portion of the surface of the second semiconductor chip, and the reverse surface of the first semiconductor chip is fixed to the reverse surface of the second semiconductor chip, and the electrode for wiring on the second semiconductor chip is exposed at a reverse surface side of the interposer via the through hole.  
         [0015]     &lt;2&gt; A semiconductor chip package further comprising: an interposer in which is formed a through hole which is larger than chip sizes of the first semiconductor chip and the second semiconductor chip; and an adhesive sheet which is a sheet-shaped adhesive material provided on a surface of the interposer so as to cover the through hole, wherein the reverse surface of the second semiconductor chip is fixed to a reverse surface of the adhesive sheet which is exposed via the through hole at an interposer reverse surface side, and the reverse surface of the first semiconductor chip is fixed to a surface of the adhesive sheet so as to oppose the reverse surface of the second semiconductor chip at a position at which the second semiconductor chip is fixed.  
         [0016]     &lt;3&gt; A semiconductor chip package further comprising: an interposer in which is formed a through hole which is smaller than a chip size of the first semiconductor chip and larger than a chip size of the second semiconductor chip, wherein the first semiconductor chip is fixed to a surface of the interposer at a portion of the reverse surface of the first semiconductor chip, such that the through hole is covered, and the reverse surface of the second semiconductor chip is fixed to the reverse surface of the first semiconductor chip which is exposed at a reverse surface side of the interposer via the through hole.  
         [0017]     In the semiconductor chip package of the present invention, it is suitable that the interposer has, at a reverse surface side thereof, a region which is sunken-in, and the through hole is provided at the sunken-in region. Because the reverse surface side of the interposer is sunken-in and the through hole is provided at the sunken-in region, in a case in which the through hole and the periphery thereof at the reverse surface of the interposer are sealed with a sealing resin material or the like, the sealing resin material is embedded in the sunken-in region, and the size of the projecting portion of the sealing portion which is exposed can be held in check. Therefore, for example, the sealing portion can be kept lower than the solder balls provided at the outer lead portions of the reverse surface of the interposer. Further, in a case in which the solder balls are provided, the mounting pitches thereof can be made small, and the diameters of the solder balls can be made small. Note that the sealing portion being low means that the portion projecting out with respect to the reverse surface of the interposer is low.  
         [0018]     In the present invention, the size of the through hole of the interposer with respect to the chip sizes of the semiconductor chips (the first semiconductor chip and the second semiconductor chip) means the size of the opening of the through hole of the interposer with respect to the opposing surface of the semiconductor chip. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]      FIG. 1  is a schematic sectional view which illustrates a semiconductor chip package of a first embodiment.  
         [0020]      FIG. 2  is a schematic plan view which illustrates an interposer of the semiconductor chip package of the first embodiment.  
         [0021]      FIG. 3  is a schematic plan view which illustrates a lower chip of the semiconductor chip package of the first embodiment.  
         [0022]      FIG. 4  is a schematic plan view which illustrates a fixed state of the lower chip of the semiconductor chip package of the first embodiment.  
         [0023]      FIG. 5  is a schematic plan view which illustrates a suitable fixed state of the lower chip of the semiconductor chip package of the first embodiment.  
         [0024]      FIG. 6  is a schematic sectional view which illustrates a semiconductor chip package of a second embodiment.  
         [0025]      FIG. 7  is a schematic sectional view which illustrates a semiconductor chip package of a third embodiment.  
         [0026]      FIG. 8  is a schematic sectional view which illustrates a semiconductor chip package of a fourth embodiment.  
         [0027]      FIG. 9  is a schematic sectional view which illustrates a semiconductor chip package of a fifth embodiment.  
         [0028]      FIG. 10  is a schematic sectional view which illustrates a conventional semiconductor chip package.  
         [0029]      FIG. 11  is a schematic plan view which illustrates an upper chip of the conventional semiconductor chip package.  
         [0030]      FIG. 12  is a schematic plan view which illustrates a lower chip of the conventional semiconductor chip package.  
         [0031]      FIG. 13  is a schematic plan view which illustrates a state in which the upper and lower chips are mounted in the conventional semiconductor chip package. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0032]     Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that structures having substantially the same functions are described by being denoted by the same numerals throughout all of the drawings.  
         [0000]     (First Embodiment)  
         [0033]     A first embodiment will be described with reference to  FIG. 1  through  FIG. 5 . Hereinafter, the structure of the semiconductor chip package illustrated in  FIG. 1  will be described in accordance with the fabrication process thereof. In the semiconductor chip package illustrated in  FIG. 1 , a through hole  16  is formed in the center of an interposer  14  which is formed from a material such as tape, glass epoxy, or the like. The through hole  16  corresponds to electrodes  24  for wiring which are aligned at the center of the surface of a lower chip  10  (a second semiconductor chip). A semiconductor chip, which is diced and separated into a desired size and in which the electrodes  24  for wiring are aligned at the at the center of the surface thereof, is fixed, as the lower chip  10  (the second semiconductor chip), onto a chip mounting position of the surface of the interposer  14  in a state in which a desired portion of the surface of the lower chip  10  is adhered to the surface of the interposer  14  by an adhesive  18  such as epoxy resin or the like. At this time, the electrodes  24  for wiring formed on the surface of the lower chip  10  are exposed at the reverse surface side of the interposer  14  via the through hole.  
         [0034]     Thereafter, the electrodes  24  for wiring of the lower chip  10  are wire-bonded to inner leads  32  which exist at the reverse surface of the interposer  14  by wiring members  20  such as metal wires or the like. Further, the respective members at the reverse surface side of the interposer  14  are resin-sealed with a resin sealing material  28  such as an epoxy resin or the like by a potting method or the like. Here, a case is described in which the sealing resin is exposed and projects out at the reverse surface of the interposer  14 . However, the amount of projection of the sealing resin can be kept sufficiently lower than the solder balls and presents no problems.  
         [0035]     Next, a semiconductor chip, which is diced and separated into a desired size and at which electrodes  26  for wiring are provided at the chip edge periphery of the surface thereof, is fixed, as an upper chip  12  (first semiconductor chip), on the lower chip  10  by the reverse surface of the upper chip  12  being adhered to the reverse surface of the lower chip  10  by the adhesive  18  such as epoxy resin or the like. Thereafter, electrodes  26  for wiring of the upper chip  12  are wire-bonded to inner leads  34 , which exist on the interposer  14 , by wiring members  22  such as metal wires or the like. Further, the respective members at the surface of the interposer  14  are resin-sealed by a resin sealing material  30  such as an epoxy resin or the like by a transfer molding method or the like. Finally, solder balls  36  are mounted on outer lead portions of the reverse surface of the interposer  14 , and the semiconductor chip package is completed.  
         [0036]     In the first embodiment, as shown in  FIG. 2 , the through hole  16  is provided at a position, at the center of the interposer  14 , which position corresponds to the electrodes  24  for wiring aligned at the center of the lower chip  10 . Here, as shown in  FIG. 3 , usually, a distance A from the electrodes  24  for wiring aligned at the center of the lower chip  10  to a chip edge is extremely short, for example, about 100 μm. In this case, in order to ensure to a certain extent the distance between the edge of the through hole  16  of the interposer  14  and the electrodes  24  for wiring, as shown in  FIG. 4 , the lower chip  10  is fixed onto a chip mounting position at the surface of the interposer  14  by the adhesive  18  (the range of application of the adhesive is shown by the hatched portion in  FIG. 4 ), with a space B being provided such that the lower chip  10  does not completely cover the through hole  16 . If the respective members at the reverse surface of the interposer  14  are resin-sealed by the resin sealing material  28  in this state, there is a problem in that resin leaks out from the space B.  
         [0037]     Thus, as shown in  FIG. 5 , preferably, the sheet-shaped adhesive  18  has the property that, due to heating, both surfaces thereof become viscous (such as a thermoplastic resin), and can fix (adhere) an object to be adhered. Further, the sheet-shaped adhesive  18  is preferably a size larger than the chip size of the lower chip  10 , and is a size which covers the space between the lower chip  10  and the through hole  16 . (Preferably, the sheet-shaped adhesive  18  is of a size which, at the long diameter direction of the through hole  16 , is about 100 μm longer at each side than the other direction.) Preferably, a portion of the surface of the lower chip  10  is temporarily adhered to the sheet-shaped adhesive  18 , and then, the surface of the lower chip  10  is fixed to the chip mounting position of the surface of the interposer  14  by the sheet-shaped adhesive  18 . A small hole, which corresponds to the electrodes  24  for wiring at the surface of the lower chip  10  and which is smaller than the chip size of the lower chip  10 , is provided in the sheet-shaped adhesive  18 . In this way, the through hole  16  of the interposer  14  can be completely covered by the lower chip  10  and the sheet-shaped adhesive  18 , and leakage of resin at the time of resin sealing can be prevented.  
         [0038]     In the first embodiment, a desired portion of the surface of the lower chip  10  is fixed onto the chip mounting position of the surface of the interposer  14  by the adhesive  18 , and the reverse surface of the upper chip  12  is fixed onto the reverse surface of the lower chip  10  by the adhesive  18 . Namely, the electrodes  26 ,  24  for wiring, which are provided at the upper chip  12  and the lower chip  10  respectively, exist at opposite surfaces of the structure formed by the upper chip and the lower chip. Therefore, the upper chip  12 , which is the same size as the lower chip  10  or is larger than the chip size of the lower chip  10 , can be mounted.  
         [0039]     In the first embodiment, the through hole  16  is provided in the interposer  14 , and the lower chip  10  and the inner leads  32  at the reverse surface of the interposer  14  are wire-bonded through the through hole  16 . Further, the upper chip  12 , at which the electrodes  26  for wiring are disposed at the chip edge periphery, can be used. Therefore, the lengths of the wiring members (wires) can be shortened. Therefore, a stable wire-bonding yield can be obtained, and further, there are advantages with regard to the electrical characteristics, such as high speed signal transmission and the like.  
         [0000]     (Second Embodiment)  
         [0040]     A second embodiment will be described with reference to  FIG. 6 . Hereinafter, the structure of the semiconductor chip package shown in  FIG. 6  will be described in accordance with the fabrication process thereof. In the semiconductor chip package shown in  FIG. 6 , the through hole  16 , which is a size larger (preferably, about 0.2 mm larger at one side) than the chip size of the upper chip  12  (the first semiconductor chip) and the lower chip  10  (the second semiconductor chip), is provided at the center of the interposer  14  which is formed by a material such as tape or glass epoxy or the like. The sheet-shaped adhesive  18 , which has the property such as that of a thermoplastic resin that when the adhesive  18  is heated, both surfaces thereof become viscous and can be adhered, is temporarily adhered to the surface of the interposer  14 . At this time, if the sheet-shaped adhesive  18  is designed as to be larger than the through hole  16  by about 100 μm at each side thereof, the through hole  16  is completely covered, and therefore, resin leakage can be prevented at the time of sealing.  
         [0041]     The semiconductor chip, which is diced and separated into a desired size and at which the electrodes  24  for wiring are provided at the chip edge periphery of the surface thereof, serves as the lower chip  10 , and the surface of the lower chip  10  is fixed to the reverse surface of the sheet-shaped adhesive  18  at which the reverse surface of the lower chip  10  is exposed from the through hole  16  so as to oppose the reverse surface side of the interposer  14 . Thereafter, the electrodes  24  for wiring of the lower chip  10  are wire-bonded with the inner leads  32  which exist at the reverse surface of the interposer  14  by the wiring members  20  which are metal wires or the like. Then, the respective members of the reverse surface of the interposer  14  are resin-sealed by the resin sealing material  28  such as an epoxy resin or the like by the transfer molding method or the like.  
         [0042]     A semiconductor chip, which is diced and separated into a desired size and at which the electrodes  26  for wiring are provided at the center of the surface thereof, serves as the upper chip  12 , and the reverse surface of the upper chip  12  is fixed to the surface of the sheet-shaped adhesive  18  so as to face the mounting position of the lower chip  10 . Thereafter, the electrodes  26  for wiring of the upper chip  12  are wire-bonded to the inner leads  34  which exist at the surface of the interposer  14  by the wiring members  22  which are metal wires or the like. Then, the respective members of the surface of the interposer  14  are resin-sealed by the resin sealing material  30  such as a epoxy resin or the like by the transfer molding method or the like. Finally, the solder balls  36  are mounted to outer lead portions at the reverse surface of the interposer  14 , and the semiconductor chip package is completed.  
         [0043]     In the second embodiment, the surface of the lower chip  10  is fixed to the reverse surface of the sheet-shaped adhesive  18  such that the reverse surface of the lower chip  10  is exposed from the through hole  16  so as to oppose the reverse surface side of the interposer  14 . The reverse surface of the upper chip  12  is fixed to the surface of the sheet-shaped adhesive  18  so as to oppose the position at which the lower chip  10  is fixed. Namely, the surfaces of the upper chip  12  and the lower chip  10 , at which the electrodes  26 ,  24  for wiring are provided respectively, exist at the surfaces at opposite sides of the structure formed by the upper chip and the lower chip. Therefore, the upper chip  12 , which is the same chip size or a greater chip size than the lower chip  10 , can be mounted.  
         [0044]     In the second embodiment, the lower chip  10  is provided within the through hole  16  provided at the interposer  14 , and the electrodes  24  for wiring of the lower chip  10  and the inner leads  32  at the reverse surface of the interposer  14  are wire-bonded. Further, because the lower chip  10  is provided within the through hole  16  provided at the interposer  14 , the height at which the upper chip  12  is disposed with respect to the interposer  14  can be kept low. Therefore, the lengths of the wiring members (wires) can be shortened. Accordingly, a stable wire-bonding yield can be obtained, and further, there are advantages with regard to the electrical characteristics, such as high speed signal transmission and the like.  
         [0000]     (Third Embodiment)  
         [0045]     A third embodiment will be described with reference to  FIG. 7 . Hereinafter, the structure of the semiconductor chip package shown in  FIG. 7  will be described in accordance with the fabrication process thereof. In the semiconductor chip package shown in  FIG. 7 , a metal substrate of aluminum or the like is used as the interposer  14 , and the reverse side thereof is sunken-in by drawing or the like, such that the through hole  16  is provided at a sunken-in region  38 . Other than this structure, the present third embodiment is the same as the above-described second embodiment, and therefore, description thereof will be omitted.  
         [0046]     In the third embodiment, the semiconductor chip package includes the interposer  14  whose reverse surface side is sunken-in, and the through hole  16  is provided at the sunken-in region  38 . Usually, in the case of a structure such as that of the above-described third embodiment, if the chip thickness of the lower chip  10  is large, because the portion sealed by the sealing resin projects out at the reverse surface of the interposer  14 , it is difficult for a sealed portion  40  to be kept sufficiently lower than the solder balls  36 . More concretely, if the number of pins increases, the mounting pitches of the solder balls  36  are small, and in order to address this, the diameters of the solder balls  36  must be of necessity be made small. Accordingly, the height of the solder ball  36  is made low. On the other hand, if the chip thickness of the lower chip  10  is sufficiently low (for example, about 100 μm), the height of the sealed portion can be kept sufficiently lower than the height of the solder balls  36 . However, in a case in which the height of the solder balls  36  is low (generally, about 300 μm or less), the above-described third embodiment cannot be utilized. Therefore, by structuring the interposer  14  as described above, even if the through hole and the periphery thereof (the periphery of the respective members at the surface of the interposer  14 ) are sealed by a sealing resin material or the like, because the sealing resin material is embedded in the depressed region  38  of the interposer  14 , the projecting of the sealed portion can be kept sufficiently lower than the height of the solder balls  36 . Further, if the mounting pitches of the solder balls  36  are small, the diameters of the solder balls can be kept small.  
         [0000]     (Fourth Embodiment)  
         [0047]     A fourth embodiment will be described with reference to  FIG. 8 . Hereinafter, the structure of the semiconductor chip package shown in  FIG. 8  will be described in accordance with the fabrication process thereof. In the semiconductor chip package shown in  FIG. 8 , the through hole, which is a size smaller than the chip size of the upper chip  12  (the first semiconductor chip) mounted on the surface of the interposer  14  and which is larger than the chip size of the lower chip  10  (the second semiconductor chip), is provided at the center of the interposer  14  which is formed by tape, glass epoxy, or the like. Further, a semiconductor chip, which is diced and separated to a desired size and at which the electrodes  26  for wiring are provided at the center of the surface, serves as the upper chip  12 . The sheet-shaped adhesive  18 , such as a thermoplastic resin, which has the property that, when heated, both sides thereof become viscous and can adhere, is temporarily adhered to the reverse surface of the upper chip  12 . Portions of the reverse surface of the upper chip  12  are fixed to overhanging regions of the interposer  14  at the periphery of the through hole  16  by the sheet-shaped adhesive  18  which is temporarily adhered in advance to the reverse surface of the upper chip  12 . Thereafter, the electrodes  26  for wiring of the upper chip  12  are wire-bonded with the inner leads  34  which exist on the surface of the interposer  14  by the wiring members  20  such as metal wires or the like. Then, the respective members at the surface of the interposer  14  are resin-sealed with the resin sealing material  30  such as an epoxy resin or the like by the transfer molding method or the like. At this time, if the upper chip  12  is designed to be larger than the through hole  16 , for example, the respective sides of the upper chip  12  are each about 0.2 μm longer than the sides of the through hole  16 , the through hole  16  can be completely covered, and thus, resin leakage can be prevented at the time of sealing.  
         [0048]     The semiconductor chip, which is diced and separated to a desired size and at which the electrodes  24  for wiring are provided at the chip edge periphery of the surface, serves as the lower chip  10 . Next, the reverse surface of the lower chip  10  is fixed by the adhesive  18  to the reverse surface of the upper chip  12  at which the reverse surface of the lower chip  10  is exposed from the through hole  16  so as to oppose the reverse surface side of the interposer  14 . Thereafter, the electrodes  24  for wiring of the lower chip  10  are wire-bonded to the inner leads  32  which exist at the reverse surface of the interposer  14  by the wiring members  20  such as metal wires or the like. Then, the respective members at the reverse surface of the interposer  14  are resin-sealed by the resin sealing material  28  such as epoxy resin or the like by the transfer molding method or the like. Finally, the solder balls  36  are mounted to the outer lead portions at the reverse surface of the interposer  14 , and the semiconductor chip package is completed.  
         [0049]     In the fourth embodiment, the upper chip  12  is fixed such that a portion of the reverse surface thereof covers the through hole  16  at the surface of the interposer  14 , and the surface of the lower chip  10  is fixed to the reverse surface of the upper chip  12  which is exposed from the through hole  16  at the reverse surface side of the interposer  14 . Namely, the surfaces of the upper chip  12  and the lower chip  10 , at which the electrodes  26 ,  24  for wiring are provided respectively, exist at opposite sides of the structure formed by the upper chip and the lower chip. In accordance with this structure, the upper chip  12 , whose chip size is larger than that of the lower chip  10 , can be mounted.  
         [0050]     In the fourth embodiment, the lower chip  10  is provided within the through hole  16  provided in the interposer  14 , and the electrodes  24  for wiring of the lower chip  10  and the inner leads  32  at the reverse surface of the interposer  14  are wire-bonded. Further, because the lower chip  10  is provided within the through hole  16  of the interposer  14 , the amount of projection of the upper chip  12  with respect to the interposer  14  can be kept low. Therefore, the lengths of the wiring members (wires) can be shortened. Accordingly, a stable wire-bonding yield can be obtained, and there are advantages with regard to the electrical characteristics, such as high speed signal transmission and the like.  
         [0000]     (Fifth Embodiment)  
         [0051]     A fifth embodiment will be described with reference to  FIG. 9 . The structure of the semiconductor chip package shown in  FIG. 9  will be described in accordance with the fabrication process thereof. In the semiconductor chip package shown in  FIG. 9 , the interposer  14  is a structure which uses a metal substrate of aluminum or the like, and whose reverse surface side is sunken-in by drawing or the like, and the through hole  16  is provided at the depressed region  38 . Except for this structure, the fifth embodiment is the same as the above-described fourth embodiment, and description will be omitted.  
         [0052]     In the fifth embodiment, the semiconductor chip package includes the interposer  14  whose reverse surface side is sunken-in, and the through hole  16  is provided at the depressed region. Thus, as in the above-described third embodiment, the projecting of the sealed portion can be kept sufficiently lower than the height of the solder balls  36 . Further, the mounting pitches of the solder balls  36  can be made to be small, and the diameters of the solder balls  36  can be made to be small.  
         [0053]     In above-described first through fifth embodiments, the structures are described in accordance with the fabrication processes thereof, but it is needless to say that the present invention is not limited to these fabrication processes. Further, in the above-described first through fifth embodiments, the terms “upper” and “lower” of the upper chip and the lower chip mean upper and lower in so far as their positions with respect to surfaces of the interposer.  
         [0054]     In the first through fifth embodiments which are described above, cases in which the positions of the electrodes for wiring on the upper chip and the lower chip are at the center or at the periphery of the chip edge are described. However, in the present invention, the positions of the electrodes for wiring are not particularly limited to these positions, and semiconductor chips in which electrodes for wiring are provided at any positions can be mounted.  
         [0055]     In the above-described first through third embodiments, cases in which the chip sizes of the upper chip and the lower chip are the same are described. However, the chip sizes of the upper chip and the lower chip can be freely changed, and the chips can be mounted with any combinations of chip sizes.  
         [0056]     The semiconductor chip packages of the present invention relating to the above-described embodiments are not to be interpreted as limiting, and can be realized within a scope satisfying the structural conditions of the present invention.