Abstract:
Disclosed herein is a semiconductor device that includes: a first circuit formed on a chip having a main surface; first to n th  penetration electrodes penetrating through the chip, where n is an integer more than 1; first to n th  main terminals arranged on the main surface of the chip and vertically aligned with the first to n th  penetration electrodes, respectively, each of k th  main terminal being electrically connected to k+1 th  penetration electrode, where k is an integer more than 0 and smaller than n, and the n th  main terminal being electrically connected to the first penetration electrode; a sub-terminal arranged on the main surface of the chip; and a selection circuit electrically connected to predetermined one of the first to n th  main terminals, the sub-terminal, and the first circuit, wherein the selection circuit connects the first circuit to one of the predetermined main terminal and the sub-terminal.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a semiconductor device, and particularly relates to a semiconductor device having a plurality of stacked semiconductor chips electrically connected to one another by penetration electrodes that penetrating through the semiconductor chips. 
         [0003]    2. Description of Related Art 
         [0004]    The storage capacity required for a semiconductor memory device such as a DRAM (Dynamic Random Access Memory) is increasing in recent years. To meet this demand, there is recently proposed a memory device called “multi-chip package” in which a plurality of memory chips are stacked. However, because of the need to provide wires connecting the respective memory chips to a package substrate, it is difficult to stack many memory chips in the multi-chip package. 
         [0005]    On the other hand, there is recently proposed a semiconductor device of such a type that a plurality of memory chips each provided with penetration electrodes are stacked. The penetration electrodes may be referred to as through silicon vias. In the semiconductor device of this type, the through silicon vias provided in each of the memory chips are connected to those provided in upper and lower memory chips. Accordingly, the number of through silicon vias connected to the package substrate does not increase even if the number of stacks increases. Therefore, it is possible to stack more memory chips (see Japanese Patent Application Laid-open Nos. 2006-313607 and 2007-158237, and International Publication No. WO2007/032184). 
         [0006]    In the stacked semiconductor device, the through silicon vias provided at the same plane position as viewed from a stacking direction, are basically short-circuited. However, as described in Japanese Patent Application Laid-open No. 2006-313607, a part of the through silicon vias are not short-circuited and those arranged at different plane positions, as viewed from the stacking direction, are often connected to one another. Such through silicon vias are used to apply different signals to the respective semiconductor chips. 
         [0007]    On the other hand, because many through silicon vias are provided in the semiconductor chips, a part of the through silicon vias often becomes defective and the defective through silicon vias need to be relieved by being replaced by auxiliary through silicon vias. Specifically, as described in Japanese Patent Application Laid-open No. 2007-158237, there is proposed a method of connecting a plurality of through silicon vias in parallel in advance or making regular through silicon vias replaceable by auxiliary through silicon vias. Furthermore, International Publication No. WO2007/032184 describes a method of commonly allocating an auxiliary through silicon via to a plurality of through silicon vias. 
         [0008]    With the method of connecting the through silicon vias in parallel, if any of the through silicon vias has a non-conductive defect, it is possible to relieve the through silicon via. However, it is impossible to relieve the through silicon via if the through silicon via has a short-circuit defect (short-circuit to a power supply line or another through silicon via). Furthermore, the large increase in the number of necessary through silicon vias causes not only the increase in an occupation area of the through silicon vias on each of the chips but also the increase in the load of the through silicon vias as a result of the parallel connection of the through silicon vias. Therefore, there is a problem that it is required to improve the capability of a driver for driving these through silicon vias. 
         [0009]    With the method of replacing the regular through silicon via by the auxiliary through silicon via, it is necessary for each through silicon via to include a switching circuit, which results in the increase in the occupation area of the through silicon vias on each chip. Particularly on a signal path on which the through silicon vias that are arranged at the different plane positions, as viewed from the stacking direction, are short-circuited, each through silicon via is used only to supply signals to one corresponding semiconductor chip and does not contribute to supplying signals to the other semiconductor chips. Therefore, it is inefficient to provide the switching circuits in all of these through silicon vias, respectively. 
       SUMMARY 
       [0010]    In one embodiment, there is provided a semiconductor device that includes: a first circuit formed on a first chip having a main surface; first to n th  penetration electrodes penetrating through the first chip, where n is an integer more than 1; first to n th  main terminals arranged on the main surface of the first chip and vertically aligned with the first to n th  penetration electrodes, respectively, each of k th  main terminal being electrically connected to k+1 th  penetration electrode, where k is an integer more than 0 and smaller than n, and the n th  main terminal being electrically connected to the first penetration electrode; a sub-terminal arranged on the main surface of the first chip; and a selection circuit electrically connected to predetermined one of the first to n th  main terminals, the sub-terminal, and the first circuit, wherein the selection circuit connects the first circuit to one of the predetermined main terminal and the sub-terminal. 
         [0011]    In another embodiment, there is provided a semiconductor device that includes: a third semiconductor chip stacked on the second semiconductor chips such that the second semiconductor chips are sandwiched between the first and third semiconductor chips; and a third signal path connecting the first semiconductor chip to the third semiconductor chip, the third signal path being formed by respective ones of the first penetration electrodes. The second signal path connects the first semiconductor chip to the second and third semiconductor chips in common. The switching circuit replaces one of the first and third signal paths by the second signal path. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a schematic cross-sectional view for explaining a structure of a semiconductor device  10  according to a proffered first embodiment of the present invention; 
           [0013]      FIGS. 2A to 2C  are diagrams indicative of an embodiment of various types of through silicon via TSV provided in a core chip; 
           [0014]      FIG. 3  is a cross-sectional view indicative of an embodiment of a structure of the through silicon via TSV 1  of the type shown in  FIG. 2A ; 
           [0015]      FIG. 4  is a cross-sectional view indicative of an embodiment of a structure of the through silicon via TSV 2  of the type shown in  FIG. 2B ; 
           [0016]      FIG. 5  is a cross-sectional view indicative of an embodiment of a structure of the through silicon via TSV 3  of the type shown in  FIG. 2C ; 
           [0017]      FIG. 6  is a schematic diagram for explaining a connection relation between through silicon vias TSV 3  in respective core chips; 
           [0018]      FIG. 7  is a schematic diagram for explaining the means for relieving the semiconductor device  10  from a defect occurring in one of the first signal paths, and shows elements related to transmission of signals from the interface IF to the core chips CC 0  to CC 7 ; 
           [0019]      FIG. 8  is a circuit diagram indicative of an embodiment of a switching circuit  110 ; 
           [0020]      FIG. 9  is a circuit diagram indicative of an embodiment of a selection circuit  120 ; 
           [0021]      FIG. 10  is a schematic diagram for explaining means for relieving the semiconductor device  10  from a defect occurring in one of the first signal paths, and shows elements related to the transmission of signals from the core chips CC 0  to CC 7  to the interface chip IF; 
           [0022]      FIG. 11  is a circuit diagram of indicative of an embodiment of the selection circuit  140 ; 
           [0023]      FIG. 12  is a circuit diagram of indicative of an embodiment of the switching circuit  150 ; 
           [0024]      FIG. 13  is a circuit diagram of indicative of an embodiment of the test circuits R 1  and R 2 ; 
           [0025]      FIG. 14  is a cross-sectional pattern diagram for explaining a semiconductor device  10   a  according to a second embodiment of the present invention; 
           [0026]      FIG. 15  is a circuit diagram indicative of an embodiment of a switching circuit  110   a ; and 
           [0027]      FIG. 12  is a circuit diagram of indicative of an embodiment of the switching circuit  150   a.    
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0028]    Preferred embodiments of the present invention will be explained below in detail with reference to the accompanying drawings. 
         [0029]    Referring now to  FIG. 1 , the semiconductor device  10  according to this embodiment has the structure where eight core chips (memory chips) CC 0  to CC 7  and an interface chip IF are stacked on an interposer IP. The core chips CC 0  to CC 7  have the same function and structure as one another. It is worth noting that the uppermost core chip CC 0  may have a different structure from the other core chips CC 1  to CC 7 . For example, the uppermost core chip CC 0  may be thicker than the remaining core chips CC 1  to CC 7 . The core chips CC 0  to CC 7  are manufactured using the same manufacture mask whereas the interface chip IF is manufactured using a manufacture mask different from that of the core chips CC 0  to CC 7 . The core chips CC 0  to CC 7  and the interface chip IF are semiconductor chips using a silicon substrate and are electrically connected to adjacent chips in a vertical direction through plural Through Silicon Vias (TSV) penetrating the silicon substrate. The through silicon via may be referred to as a penetration electrode. The uppermost core chip CC 0  may not have the through silicon via TSV. Meanwhile, the interposer IP is a circuit board that is made of a resin, and plural external terminals (solder balls) SB are formed in a back surface IPb of the interposer IP. 
         [0030]    The core chips CC 0  to CC 7  are semiconductor chips from which a so-called front-end portion, which performs an interface with an outside, of circuit blocks included in a normal stand-alone SDRAM (Synchronous Dynamic Random Access Memory), is removed. That is, each of the core chips CC 0  to CC 7  is a memory chip where only the circuit blocks belonging to the back end unit are integrated in principle. As the circuit blocks that are included in the front end unit, a parallel-serial converting circuit that performs parallel/serial conversion on input/output data between a memory cell array and a data input/output terminal and a DLL (Delay Locked Loop) circuit that controls input/output timing of data are exemplified, which will be described in detail below. 
         [0031]    On the other hand, the interface chip IF is a semiconductor chip on which only the front-end portion of the circuit blocks included in the normal stand-alone SDRAM is integrated. The interface chip IF functions as a front-end portion common to 8 core chips CC 0  to CC 7 . Accordingly, all of the external accesses are made through the interface chip IF, and data input and data output are made through the interface chip IF. 
         [0032]    In this embodiment, the interface chip IF is disposed between the interposer IP and the core chips CC 0  to CC 7 . However, the position of the interface chip IF is not restricted in particular, and the interface chip IF may be disposed on the core chips CC 0  to CC 7  and may be disposed on the back surface IPb of the interposer IP. When the interface chip IF is disposed on the core chips CC 0  to CC 7  in a face-down manner or is disposed on the back surface IPb of the interposer IP in a face-up manner, the through silicon via TSV does not need to be provided in the interface chip IF. The interface chip IF may be disposed to be interposed between the two interposers IP. 
         [0033]    The interposer IP functions as a rewiring substrate to increase an electrode pitch and secures mechanical strength of the semiconductor device  10 . That is, an electrode  91  that is formed on a top surface IPa of the interposer IP is drawn to the back surface IPb via a through-hole electrode  92  and the pitch of the external terminals SB is enlarged by the rewiring layer  93  provided on the back surface IPb. In  FIG. 1 , only the two external terminals SB are shown. In actuality, however, three or more external terminals are provided. The layout of the external terminals SB is the same as that of the DDR3-type SDRAM that is determined by the regulation. Accordingly, the semiconductor memory device can be treated as one DDR3-type SDRAM from the external controller. 
         [0034]    As shown in  FIG. 1 , a top surface of the uppermost core chip CC 0  is covered by an NCF (Non-Conductive Film)  94  and a lead frame  95 . Gaps between the core chips CC 0  to CC 7  and the interface chip IF are filled with an underfill  96  and surrounding portions of the gaps are covered by a sealing resin  97 . Thereby, the individual chips are physically protected. 
         [0035]    When most of the through silicon vias TSV provided in the core chips CC 0  to CC 7  are two-dimensionally viewed from a lamination direction, that is, viewed from an arrow A shown in  FIG. 1 , the through silicon vias TSV are short-circuited from the through silicon vias TSV of other layers provided at the same position. That is, as shown in  FIG. 2A , the vertically disposed through silicon vias TSV 1  that are provided at the same position in plain view are short-circuited, and one wiring line is configured by the through silicon via TSV 1 . The through silicon via TSV 1  that are provided in the core chips CC 0  to CC 7  are connected to internal circuits  4  in the core chips, respectively. Accordingly, input signals (command signal, address signal, etc.) that are supplied from the interface chip IF to the through silicon vias TSV 1  shown in  FIG. 2A  are commonly input to the internal circuits  4  of the core chips CC 0  to CC 7 . Output signals (data etc.) that are supplied from the core chips CC 0  to CC 7  to the through silicon via TSV 1  are wired-ORed and input to the interface chip IF. 
         [0036]    Meanwhile, as shown in  FIG. 2B , the a part of the through silicon vias TSV are not directly connected to the through silicon via TSV 2  of other layers provided at the same position in plain view but are connected to the through silicon via TSV 2  of other layers through the internal circuits  5  provided in the core chips CC 0  to CC 7 . That is, the internal circuits that are provided in the core chips CC 0  to CC 7  are cascade-connected through the through silicon via TSV 2 . This kind of through silicon via TSV 2  is used to sequentially transmit predetermined information to the internal circuits  5  provided in the core chips CC 0  to CC 7 . As this information, chip address information. 
         [0037]    Another part of the through silicon vias TSV is short-circuited from the through silicon vias TSV of other layer provided at the different position in plan view, as shown in  FIG. 2C . With respect to this kind of through silicon vias TSV group  3 , internal circuits  6  of the core chips CC 0  to CC 7  are connected to the through silicon via TSV 3   a  provided at the predetermined position P in plain view. Thereby, information can be selectively input to the internal circuits  6  provided in the core chips. As this information, defective chip information to be described below is exemplified. By using the through silicon vias TSV 3 , it is also possible to supply information individually from each of the core chips CC 0  to CC 7  to the interface chip IF. 
         [0038]    As such, as types of the through silicon vias TSV provided in the core chips CC 0  to CC 7 , three types (TSV 1  to TSV 3 ) shown in  FIGS. 2A to 2C  exist. As described above, most of the through silicon vias TSV are of a type shown in  FIG. 2A , and an address signal and a command signal, and the like are supplied from the interface chip IF to the core chips CC 0  to CC 7 , through the through silicon via TSV 1  of the type shown in  FIG. 2A . Read data and write data are input to and output from the interface chip IF through the through silicon via TSV 1  of the type shown in  FIG. 2A . Meanwhile, the through silicon vias TSV 2  and TSV 3  of the types shown in  FIGS. 2B and 2C  are used to provide individual information to the core chips CC 0  to CC 7  having the same structure. 
         [0039]    Turning to  FIG. 3 , the through silicon via TSV 1  is provided to penetrate a silicon substrate  80  and an interlayer insulating film  81  provided on a surface of the silicon substrate  80 . Around the through silicon via TSV 1 , an insulating ring  82  is provided. Thereby, the through silicon via TSV 1  and a transistor region are insulated from each other. In an example shown in  FIG. 3 , the insulating ring  82  is provided double. Thereby, capacitance between the through silicon via TSV 1  and the silicon substrate  80  is reduced. 
         [0040]    An end  83  of the through silicon via TSV 1  at the back surface of the silicon substrate  80  is covered by a back surface bump  84 . The back surface bump  84  is an electrode that contacts a surface bump  85  provided in a core chip of a lower layer. The surface bump  85  is connected to an end  86  of the through silicon via TSV 1 , through plural pads P 0  to P 3  provided in wiring layers L 0  to L 3  and plural through-hole electrodes TH 1  to TH 3  connecting the pads to each other. Thereby, the surface bump  85  and the back surface bump  84  that are provided at the same position in plain view are short-circuited. Connection with internal circuits (not shown in the drawings) is performed through internal wiring lines (not shown in the drawings) drawn from the pads P 0  to P 3  provided in the wiring layers L 0  to L 3 . 
         [0041]    Turning to  FIG. 4 , the through silicon via TSV 2  is different from the through silicon via TSV 1  shown in  FIG. 3  in that the through hole electrodes TH 2  that directly connect the pads P 1  and P 2  located at the same plan position to each other are deleted. The pad P 1  is connected to, for example, an output node of the internal circuit  5  shown in  FIG. 2 , and the pad P 2  is connected to, for example, an input node of the internal circuit  5  shown in  FIG. 2 . This causes the respective internal circuits  5  provided in the core chips CC 0  to CC 7  to be cascaded through the through silicon vias TSV 2 . 
         [0042]    Turning to  FIG. 5 , in the through silicon vias TSV 3 , not the pads P 1  and P 2  located at the same plan position but the pads P 1  and P 2  located at different plan positions are connected by the though hole electrodes TH 2 . Although only three through silicon vias TSV 3  are shown in  FIG. 5 , the through silicon vias TSV 3  are provided in each of the core chips CC 0  to CC 7  by the number of core chips per signal (that is, eight). The eight through silicon vias TSV 3  are connected cyclically as shown in  FIG. 6 . In  FIG. 6 , the front bumps  85  are shown by solid lines and the back bumps  84  are shown by broken lines. When the through silicon vias TSV 3  are connected cyclically as shown in  FIG. 6 , different information can be supplied to each of the core chips CC 0  to CC 7  from the interface chip IF while the core chips CC 0  to CC 7  have the same circuit configuration. For example, when the internal circuit  6  is connected at the position of the back bump  84 - 7 , signals supplied from the interface chip IF to the back bumps  84 - 0  to  84 - 7  of the lowermost core chip CC 7  are selectively supplied to the internal circuits  6  of the core chips CC 0  to CC 7 , respectively. 
         [0043]    In this way, a signal path that is formed by cyclically connecting the through silicon vias TSV 3  of the type shown in  FIG. 2C  is often referred to as “first signal path” in the present invention. In the first embodiment, eight first signal paths are formed and those first signal paths are allocated to the corresponding core chips CC 0  to CC 7 , respectively. On the other hand, a signal path that is formed by the through silicon vias TSV 1  of the type shown in  FIG. 2A  is often referred to as “second signal path”. The second signal path is a signal path common to the core chips CC 0  to CC 7 . Means for relieving the semiconductor device  10  from a defect occurring in one of the first signal paths are described in more detail. 
         [0044]    Turning to  FIG. 7 , the hatched elements shown on lower sides of the respective core chips CC 0  to CC 7  correspond to the through silicon vias TSV provided to penetrate through the core chips CC 0  to CC 7 . Among these through silicon vias, eight through silicon vias  101  to  108  shown on the right of  FIG. 7  and provided in each of the core chips CC 0  to CC 7  are the through silicon vias TSV 3  of the type shown in  FIG. 2C . One through silicon via  109  shown on the left of the through silicon vias  101  to  108  and provided in each of the core chips CC 0  to CC 7  is the through silicon via TSV 1  of the type shown in  FIG. 2A . 
         [0045]    As shown in  FIG. 7 , the through silicon vias  101  to  108  provided in each of the core chips CC 0  to CC 7  are connected to the through silicon vias  108  and  101  to  107  provided in the upper core chip, respectively, and connected to the through silicon vias  102  to  108  and  101  provided in the lower core chip, respectively. The eight first signal paths described above are thereby formed. The through silicon vias  101  provided in the core chips CC 0  to CC 7  are connected to selection circuits  120  within the respective core chips CC 0  to CC 7 . That is, the through silicon vias  101  correspond to the through silicon vias TSV 3   a  shown in  FIG. 2C , and are arranged on the same plane position as viewed from a stacking direction. With this configuration, output signals output from buffers  201  to  208  included in the interface chip IF are supplied to the selection circuits  120  included in the core chips CC 0  to CC 7  via the eight first signal paths allocated to the core chips CC 0  to CC 7 , respectively. 
         [0046]    Meanwhile, as shown in  FIG. 7 , the through silicon vias  109  provided in the core chips CC 0  to CC 7  match one another in plane position as viewed from the stacking direction. As described above, because the through silicon vias  109  correspond to the through silicon vias TSV 1  of the type shown in  FIG. 2A , the through silicon vias  109  provided in the respective core chips CC 0  to CC 7  are short-circuited to one another. As a result, the through silicon vias  109  constitute the second signal path common to the core chips CC 0  to CC 7 . 
         [0047]    The second signal path constituted by the through silicon vias  109  is a signal path that replaces one first signal path constituted by the through silicon vias  101  to  108 . A switching circuit  110  provided in the interface chip IF and the selection circuits  120  provided in the respective core chips CC 0  to CC 7  perform a replacing operation. 
         [0048]    The switching circuit  110  is a circuit that selects one of the signals output from the buffers  201  to  208  and that switches whether the selected signal is output to the second signal path. The switching circuit  110  selects one of the signals output from the buffers  201  to  208  in response to a selection signal TAF, and switches whether the selected signal is output to the second signal path in response to a test signal TEST. 
         [0049]    Turning to  FIG. 8 , the switching circuit  110  is configured to include a decoder circuit DEC 1  and tri-state inverters  111  to  119 . The decoder circuit DEC 1  decodes signals TAF 1  to TAF 3  of three bits that constitute the selection signal TAF, and thereby activates one of the eight tri-state inverters  111  to  118 . Signals IN 11  to IN 18  output from the buffers  201  to  208  are supplied to input nodes of the tri-state inverters  111  to  118 , respectively. Output nodes of the tri-state inverters  111  to  118  are short-circuited and connected to an input node of the tri-state inverter  119 . An output node of the tri-state inverter  119  is connected to the second signal path, and changes into a high impedance state when the test signal TEST is activated to a high level. 
         [0050]    With the above configuration, when the test signal TEST is deactivated to a low level, one of the signals IN 11  to IN 18  is output to the second signal path. A state in which the test signal TEST is deactivated to a low level represents a state during a normal operation. The selection signal TAF is held in a fuse circuit (not shown) included in the interface chip IF and supplied from the fuse circuit in response to the power being turned on. 
         [0051]    On the other hand, the selection circuit  120  provided in each of the core chips CC 0  to CC 7  is the circuit that selects one of the first signal path allocated to the core chip and the second signal path as a signal path via which signals are input to the core chip. The selection circuit  120  selects the first or second signal path in response to the corresponding selection signals S 1  to S 8 . Only one of the selection signals S 1  to S 8  is activated at the most and the activation of the two or more selection signals is prohibited. Note that the selection signals S 1  to S 8  are equivalent to a decoding result of decoding the selection signal TAF. 
         [0052]    Turning to  FIG. 9 , the selection circuit  120  is configured to include two tri-state inverters  121  and  122 . As for these tri-state inverters  121  and  122 , a signal IN 1  from the first signal path is supplied to an input node of the tri-state inverter  121 , and a signal IN 2  from the second signal path is supplied to an input node of the tri-state inverter  122 . Output nodes of the tri-state inverters  121  and  122  are short-circuited, and a signal OUT output from a short-circuited node is supplied to an internal circuit  130  shown in  FIG. 7 . Because one of these tri-state inverters  121  and  122  is activated in response to the corresponding selection signals S 1  to S 8 , one of the signal IN 1  supplied via the first signal path and the signal IN 2  supplied via the second signal path is supplied to the internal circuit  130 . 
         [0053]    The selection signals S 1  to S 8  are held in a fuse circuit (not shown) included in the interface chip IF, and transferred to the respective core chips CC 0  to CC 7  via the other through silicon vias TSV (not shown) from the fuse circuit in response to the power being turned on. As described above, the selection signals S 1  to S 8  match the decoding result of decoding the selection signal TAF. Therefore, a common fuse circuit can be used to hold both the selection signal TAF and the selection signals S 1  to S 8 . 
         [0054]    As described above, even if one of the first signal paths is defective, specific signals to be supplied to the corresponding core chip can be correctly supplied to the core chip by replacing the defective first signal path by the second signal path. As an example, when a through silicon via  108   x  shown in  FIG. 7  is defective, the first signal path allocated to the core chip CC 0  is defective. In this case, in the interface chip IF, the tri-state inverter  111  is selected, thereby supplying the signal IN 11  output from the buffer  201  to the second signal path. In the core chip CC 0 , the selection signal S 1  is activated to a high level, thereby selecting the second signal path. The specific signals to be supplied from the interface chip IF to the core chip CC 0  are supplied to the core chip CC 0  not via the first signal path but via the second signal path. 
         [0055]    In  FIG. 10 , like elements as those shown in  FIG. 7  are denoted by like reference characters and redundant explanations thereof will be omitted. As shown in  FIG. 10 , selection circuits  140  provided in the respective core chips CC 0  to CC 7  and a switching circuit  150  and selection circuits  161  to  168  provided in the interface chip IF perform a replacing operation for replacing one of the first signal paths by the second signal path. 
         [0056]    The selection circuit  140  provided in each of the core chips CC 0  to CC 7  is the circuit that selects one of the first signal path allocated to the core chip and the second signal path as a signal path via which signals are output from the core chip. The selection circuit  140  selects the first or second signal path in response to the corresponding selection signals S 1  to S 8 . 
         [0057]    Turning to  FIG. 11 , the selection circuit  140  is configured to include two tri-state inverters  141  and  142 . A signal IN supplied from the internal circuit  130  is commonly supplied to input nodes of the tri-state inverters  141  and  142 . One of the tri-state inverters  141  and  142  is activated in response to the corresponding selection signals S 1  to S 8 , and both of the tri-state inverters  141  and  142  are deactivated when the test signal TEST is activated to a high level. An output node of the tri-state inverter  141  is connected to the first signal path, and an output node of the tri-state inverter  142  is connected to the second signal path. 
         [0058]    With this configuration, when the test signal TEST is deactivated to a low level, the signal IN supplied from the internal circuit  130  is output to one of the first and second signal paths based on a logic level of the corresponding selection signals S 1  to S 8 . On the other hand, when the test signal TEST is activated to a high level, an output from the selection circuit  140  changes into a high impedance state. 
         [0059]    Meanwhile, the switching circuit  150  is the circuit that selects one of the selection circuits  161  to  168  that is connected to the first signal path to be replaced by the second signal path. The switching circuit  150  selects one of the selection circuits  161  to  168  in response to the selection signal TAF. 
         [0060]    Turning to  FIG. 12 , the switching circuit  150  is configured to include a decoding circuit DEC 2  that decodes the selection signal TAF, and a transistor  151  that applies a ground potential VSS to the through silicon via  109 . The decoder circuit DEC 2  decodes the signals TAF 1  to TAF 3  of three bits that constitute the selection signal TAF, and thereby activates one of eight switching signals SEL 1  to SEL 8  to a high level. These switching signals SEL 1  to SEL 8  are supplied to the eight selection circuits  161  to  168  shown in  FIG. 10 , respectively. The selection circuits  161  to  168  are identical in circuit configuration to the selection circuit  120  shown in  FIG. 9 . Each of the selection circuits  161  to  168  selects one of two input signals and outputs the selected signal. Each of the selection circuits  161  to  168  determines which signal is to be selected based on the corresponding switching signals SEL 1  to SEL 8 . 
         [0061]    The transistor  151  is connected between the through silicon via  109  that constitutes the second signal path and a ground wire, and an enable signal EN is supplied to a gate electrode of the transistor  151 . The enable signal EN is a signal that becomes a high level when the first path is replaced by the second signal path, and that becomes a low level when the first path is not replaced by the second signal path. As a result, the transistor  151  is turned off when the first path is replaced by the second signal path, and is turned on when the first path is not replaced by the second signal path. This configuration can prevent the through silicon via  109  that constitutes the second signal path from changing into a floating state when the first path is not replaced by the second signal path. 
         [0062]    With the above configuration, even if one of the first signal paths is defective, the specific signals output from each core chip can be correctly supplied to the interface chip IF by replacing this defective first signal path by the second signal path. As an example, when the through silicon via  108   x  shown in  FIG. 10  is defective, the first signal path allocated to the core chip CC 0  is defective. In this case, in the core chip CC 0 , the selection signal S 1  is activated to a high level, thereby selecting the second signal path. In the interface chip IF, the switching signal SEL 1  is activated to a high level, whereby the selection circuit  161  selects the second signal path. The specific signals to be supplied from the core chip CC 0  to the interface chip IF are thereby supplied to the interface chip IF not via the first signal path but via the second signal path. 
         [0063]    In  FIGS. 7 and 10 , elements denoted by reference characters R 1  and R 2  are test circuits for the through silicon vias  101  to  108 . That is, after the semiconductor device  10  is manufactured, the through silicon vias  101  to  108  are tested using the test circuits R 1  and R 2 . As a result, when a defect is found in any one of the through silicon vias  101  to  108 , the corresponding first signal path is replaced by the second signal path, thereby relieving the semiconductor device  10 . 
         [0064]    Turning to  FIG. 13 , each test circuit R 1  is provided in each of the core chips CC 0  to CC 7  and each test circuit R 2  is provided in the interface chip IF. The test circuit R 1  is the circuit that supplies a test potential to the corresponding through silicon vias  101  to  108 , and the test circuit R 2  is the circuit that detects the test potential via the corresponding through silicon vias  101  to  108 . However, each test circuit R 1  can be provided in the interface chip IF and that each test circuit R 2  can be provided in each of the core chips CC 0  to CC 7  conversely to the example shown in  FIG. 13 . 
         [0065]    The test circuit R 1  is configured to include a transistor  301  that is connected between a power supply wire and the through silicon vias  101  to  108 , and a transistor  302  that is connected between a ground wire and the through silicon vias  101  to  108 . Test signals TEST 1  and TEST 2  are supplied to gate electrodes of the transistors  301  and  302 , respectively. Accordingly, when the test signal TEST 1  is activated to a high level, a power supply potential VDD is applied to the corresponding through silicon vias  101  to  108  as the test potential. When the test signal TEST 2  is activated to a high level, the ground potential VSS is applied to the corresponding through silicon vias  101  to  108  as the test potential. During a normal operation, the test signals TEST 1  and TEST 2  are both at a low level, whereby the test circuit R 1  is in a high impedance state as viewed from the through silicon vias  101  to  108 . As a result, the test circuit R 1  has no influence on a buffer circuit  210  during the normal operation. 
         [0066]    The test circuit R 2  is configured to include a transfer gate  303  that is connected between a monitor terminal MONI and the through silicon vias  101  to  108 . When the test signal TEST is activated to a high level, the transfer gate  303  becomes conductive to connect the monitor terminal MONI to the through silicon vias  101  to  108 . Furthermore, the test signal TEST is also supplied to a tri-state inverter  220  that is used during a normal operation. During a test operation during which this test signal TEST is at a high level, an output node of the tri-state inverter  220  is in a high impedance state. Because of this high impedance state, during the test operation, the tri-state inverter  220  has no influence on the test circuit R 2 . On the other hand, during the normal operation, the transfer gate  303  has no influence on the test circuit R 2  because the transfer gate  303  is in the high impedance state. 
         [0067]    During the test operation, the test signals TEST 1  and TEST 2  are sequentially activated to a high level in a state of activating the test signal TEST to a high level. For example, when the test signals TEST 1  and TEST 2  are activated in this order, the power supply potential VDD and the ground potential VSS are supposed to appear on the monitor terminal MONI in this order unless a defect occurs in any of the corresponding through silicon vias. On the other hand, if levels that appear on the monitor terminal MONI differ from those described above, there is a probability that a non-conductive defect or a short-circuit defect (short-circuit to the power supply line or the other through silicon via) occurs in any of the corresponding through silicon vias. 
         [0068]    When such a defect is found, information on the defect is programmed in the fuse circuit included in the interface chip IF so as to replace the first signal path constituted by the through silicon vias that include the defective through silicon via by the second signal path. Accordingly, when the semiconductor device  10  is actually used, the selection signal TAF and the selection signals S 1  to S 8  are output from the fuse circuit in response to the power being turned on, and the first signal path including the defect is correctly replaced by the second signal path. 
         [0069]    As described above, according to the first embodiment, even if one of the first signal paths is defective, the semiconductor device  10  can be relieved by replacing this defective first signal path by the second signal path. It is also possible to improve the production yield because the semiconductor device  10  can be relieved whether the defect is a non-conductive defect or a short-circuit defect. Furthermore, in the first embodiment, it suffices to use a small number of through silicon vias  109  necessary for the relief and there is no need to provide a switching circuit to correspond to each through silicon via, and thus it is possible to suppress the increase in an occupation area of the through silicon vias on each of chips. 
         [0070]    Turning to  FIG. 14 , the semiconductor device  10   a  according to the second embodiment is constituted to stack the four core chips CC 0  to CC 3  including identical functions and manufactured by the use of the same manufacturing mask, one interface chip IF manufactured by the use of a manufacturing mask different from the manufacturing mask for the core chips CC 0  to CC 3 , and one interposer IP. The core chips CC 0  to CC 3  and the interface chip IF are semiconductor chips using the silicon substrate, and stacked on the interposer IP in a face-down manner. The face-down manner is a manner of mounting semiconductor chips so that principal surfaces of the semiconductor chips on which electronic circuits such as transistors are formed face down, that is, so that the principal surfaces face the interposer IP. 
         [0071]    However, the semiconductor device according to the present invention is not limited to the face down manner but the respective semiconductor chips can be stacked in a face-up manner. The face-up manner is a manner of mounting semiconductor chips so that the principal surfaces of the semiconductor chips on which electronic circuits such as transistors are formed face up, that is, so that the principal surfaces face a side opposite to the interposer IP. Alternatively, a mixture of semiconductor chips stacked in the face-down manner and those stacked in the face-up manner can be mounted. 
         [0072]    Among these semiconductor chips, many through silicon vias TSV that penetrate through the silicon substrate are provided in the core chips CC 1  to CC 3  and the interface chip IF but not provided in the core chip CC 0  located on an uppermost layer. The surface bumps  85  are provided on the principal surface of each chip at a position at which the front surface bumps  85  overlap the through silicon vias TSV in a plan view as viewed from the stacking direction, and the rear surface bumps  84  are provided on the rear surface of the chip. The rear surface bumps  84  of the semiconductor chip located on a lower layer contact the front surface bumps  85  of the semiconductor chip located on an upper layer. The semiconductor chips adjacent vertically are thereby electrically connected to one another. 
         [0073]    In the second embodiment, the through silicon vias TSV are not provided in the core chip CC 0  on the uppermost layer because the chips are stacked in the face-down manner, and therefore it is unnecessary to form bump electrodes on the rear surface of the core chip CC 0 . If the through silicon vias TSV are not provided in the core chip CC 0  on the uppermost layer as described above, the core chip CC 0  on the uppermost layer can be made thicker than the other core chips CC 1  to CC 3 . Accordingly, this configuration can reduce warpage of the chip that tends to occur on the uppermost layer and can intensify mechanical strength. Furthermore, this configuration can simplify a step of making the core chip CC 0  thin. However, in the present invention, the through silicon vias TSV can be provided in the core chip CC 0  on the uppermost layer. In this case, it is possible to manufacture all of the core chips CC 0  to CC 3  in the same steps. 
         [0074]    Also in the second embodiment, the through silicon vias TSV 1  and TSV 3  having the structures shown in  FIGS. 2A and 2C  are provided in the core chips CC 1  to CC 3 . Although no through silicon vias are provided in the core chip CC 0 , each of the front surface bumps  85  of the core chip CC 0  provided at the same position as those of the through silicon vias TSV 3  of the core chips CC 1  to CC 3  in the plan view is connected to the pads P 0  and P 1  provided at the different positions in the plan view, similarly to the structure shown in  FIG. 5 . Signal paths SP shown in  FIG. 14  thereby function to independently connect the core chips CC 0  to CC 3  to the interface chip IF by the cyclical connection, respectively, similarly to the first signal paths (the through silicon vias  101  to  108 ) shown in  FIGS. 7 and 10 . On the other hand, each of the front surface bumps  85  of the core chip CC 0  provided at the same position as those of the through silicon vias TSV 1  of the core chips CC 1  to CC 3  in the plan view is connected to the pads P 0  to P 3  provided at the different positions in the plan view, similarly to the structure shown in  FIG. 3 . A signal path RD shown in  FIG. 14  thereby functions similarly to the second signal path (the through silicon via  109 ) shown in  FIGS. 7 and 10 . 
         [0075]    Therefore, in the second embodiment, similarly to the first embodiment described above, even if a defect occurs in a part of the signal paths SP, the defective signal path SP can be replaced by the signal path RD. In the second embodiment, the signals TAF 1  and TAF 2  of two bits constitute the selection signal TAF for selecting one of the core chips CC 0  to CC 3  because the number of the core chips is four, that is, the core chips are CC 0  to CC 3 . Furthermore, differently from the first embodiment, the four buffers  201  to  204  are used in place of the eight buffers  201  to  208  shown in  FIG. 7 . Furthermore, the four selection circuits  161  to  164  are used in place of the eight selection circuits  161  to  164  shown in  FIG. 10 . The second embodiment is described in more detail below. 
         [0076]    Turning to  FIG. 15 , the switching circuit  110   a  used in the second embodiment is configured to include a decoder circuit DEC 3  and tri-state inverters  111  to  114 . The decoder circuit DEC 3  decodes signals TAF 1  and TAF 2  of two bits that constitute the selection signal TAF, and thereby activates one of the four tri-state inverters  111  to  114 . Signals IN 11  to IN 14  output from the buffers  201  to  204  are supplied to input nodes of the tri-state inverters  111  to  114 , respectively. Output nodes of the tri-state inverters  111  to  114  are short-circuited and connected to an input node of the tri-state inverter  119 . An output node of the tri-state inverter  119  is connected to the signal path RD, and changes into a high impedance state when the test signal TEST is activated to a high level. With this configuration, the switching circuit  110   a  performs the same operation as the switching circuit  110  shown in  FIG. 8 . 
         [0077]    Similar circuits to the circuits shown in  FIGS. 9 and 11  can be used as the selection circuits  120  and  140 , respectively, except for using the selection signals S 1  to S 4  instead of the selection signal S 1  to S 8 . 
         [0078]    Turning to  FIG. 16 , the switching circuit  150   a  used in the second embodiment is configured to include a decoding circuit DEC 4  that decodes the selection signal TAF, and a transistor  151  that applies a ground potential VSS to the front surface bumps  85  of the core chip CC 3 . An enable signal EN is supplied to the gate electrode of the transistor  151 . The decoder circuit DEC 4  decodes the signals TAF 1  and TAF 2  of two bits that constitute the selection signal TAF, and thereby activates one of four switching signals SEL 1  to SEL 4  to a high level. 
         [0079]    As described above, even if one of the first signal paths SP is defective, specific signals to be supplied to the corresponding core chip can be correctly supplied to the core chip by replacing the defective signal path SP by the signal path RD. Further, even if one of the first signal paths SP is defective, specific signals to be output from the corresponding core chip can be correctly supplied to the interface chip IF by replacing the defective signal path SP by the signal path RD. 
         [0080]    It is apparent that the present invention is not limited to the above embodiments, but may be modified and changed without departing from the scope and spirit of the invention. 
         [0081]    For instance, in the above embodiments, the semiconductor device  10  or  10   a  constituted to stack the interface chip IF and the core chips CC 0  to CC 7  or CC 0  to CC 3  has been described as an example. However, the present invention is also applicable to any semiconductor device as long as the semiconductor device is configured to include a first semiconductor chip and a plurality of stacked second semiconductor chips. That is, in the above embodiments, the interface chip IF corresponds to the first semiconductor chip and the core chips CC 0  to CC 7  or CC 0  to CC 3  correspond to the second semiconductor chips, respectively. 
         [0082]    Furthermore, in the embodiments described above, the eight core chips CC 0  to CC 7  or the four core chips CC 0  to CC 3  are stacked on the interface chip IF. However, the number of stacked second semiconductor chips is not limited to thereto. If the number of stacked second semiconductor chips increases, the number of through silicon vias that constitute the first signal path increases. Therefore, the effects of the present invention are more significant when the number of stacked second semiconductor chips is larger.