Abstract:
A semiconductor chip is provided. The semiconductor chip includes a semiconductor substrate, a circuit on the substrate, an insulating layer formed on the circuit, and a plurality of electrically floating conductor lines formed on the insulating layer, at a major surface of the semiconductor chip.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
     This application is a Divisional of and claims the benefit of priority to U.S. patent application Ser. No. 12/968,592 filed on Dec. 15, 2010, now U.S. Pat. No. 8,217,519, which claims the benefit of priority and is a Divisional of U.S. patent application Ser. No. 12/032,430 filed on Feb. 15, 2008, now U.S. Pat. No. 7,888,806, which claims the priority of Korean Patent Application No. 2007-0073476, filed on Jul. 23, 2007, in the Korean Intellectual Property Office, the disclosure of each of which is incorporated herein in its entirety by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to multichip modules and more particularly to the manner in which electrical connections are made to the module or between chips in the module. 
     2. Description of the Related Art 
     As electronic products move to smaller size and higher density and performance, semiconductors have correspondingly become smaller with their components and connections becoming denser. This in turn has lead to the development of multichip package (MCPs) in which a plurality of semiconductor chips are stacked on a substrate such as a printed circuit board. This creates a high density, high performance package that is nonetheless small in size. 
     As density increases and size decreases, however, problems may develop with multichip modules. For example, in  FIG. 1 , an MCP includes a first semiconductor chip  10  mounted on a substrate  12 . A second semiconductor chip  14  is mounted on semiconductor chip  10  thereby forming an MCP comprising semiconductor chips  10 ,  14 . Chip  10 , which is larger than chip  14 , includes terminals such as terminals  16 ,  18 . Chip  14  also includes terminals, like terminals  20 ,  22 . As can be seen, the terminals on chip  14  are spaced much more closely together than those on chip  10 . The terminals on both chips are electrically connected to conductive pads, like pads  24 ,  26 , formed on substrate  12  via wire bonds, such as wire bonds  28 ,  30 . 
     The terminals on chip  14 , like terminals  20 ,  22 , are further away and higher from substrate  12  than the terminals, like terminals  16 ,  18 , on chip  10 . As a result, the wire bonds connecting the terminals on chip  14  to substrate  12  are longer and form a greater angle relative to the substrate than the wire bonds that connect the terminals on chip  10  to the substrate pads. And the terminals on chip  14  are much closer together. All these factors may combine to produce wire sweeping, in which the wire bonds connecting the terminals on chip  14  to the substrate pads electrically short against one another. Also, the longer each wire bond, the more likely the wire will be broken during manufacturing, e.g., when the wires are encapsulated. 
     In addition to these problems, when the terminals are close together as on chip  14 , there is a limit to how many adjacent terminals can be wire bonded to the substrate. As seen in  FIG. 1 , there is a gap indicated generally at  31  that must be included because the density and length of the bonds limit the number of adjacent wire bond connections. 
     It would be desirable to provide wire bonds or other electrical connections on the upper chip of an MCP that are shorter and have a smaller bonding angle relative to the substrate. One approach uses a redistribution network, but it cannot be employed in some types of chips because the chip design must include certain electrical characteristics, and this complicates chip design. 
     Another approach uses an interposer, but this increases fabrication cost and does not completely resolve the problems associated with long wires, terminals at a high elevation relative to the substrate, and large bonding angles. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an enlarged partial view of a prior art MCP. 
         FIG. 2  is a top plan view of a semiconductor chip constructed in accordance with the present invention. 
         FIG. 3  is an enlarged cross sectional view taken along line  3 - 3  in  FIG. 2 . 
         FIG. 4  is a second embodiment of the present invention depicted in a view similar to  FIG. 3 . 
         FIG. 5  is a top plan view of a third embodiment of the present invention. 
         FIG. 6  is a top plan view of a fourth embodiment of the present invention. 
         FIG. 7  is a fifth embodiment of the present invention depicted in a view similar to  FIGS. 3 and 4 . 
         FIG. 8  is a top plan view of a sixth embodiment of the present invention. 
         FIG. 9  is a perspective, somewhat schematic view of a first MCP constructed in accordance with the present invention. 
         FIG. 10  is a perspective, somewhat schematic view of a second MCP constructed in accordance with the present invention. 
         FIG. 11  is a perspective, somewhat schematic view of a third MCP constructed in accordance with the present invention. 
         FIG. 12  is a perspective, somewhat schematic view of a fourth MCP constructed in accordance with the present invention. 
         FIG. 13  is a perspective, somewhat schematic view of a fifth MCP constructed in accordance with the present invention. 
         FIG. 14  is a cross sectional view of the fifth embodiment of the present invention. 
         FIG. 15  is a perspective, somewhat schematic view of a sixth MCP constructed in accordance with the present invention. 
         FIG. 16  is a cross sectional view of the sixth embodiment of the present invention. 
         FIG. 17  is a perspective, somewhat schematic view of a seventh MCP constructed in accordance with the present invention. 
         FIG. 18  is a top, plan, somewhat schematic view of a eighth MCP constructed in accordance with the present invention. 
         FIG. 19  is a schematic diagram of a card constructed in accordance with the present invention. 
         FIG. 20  is a schematic diagram of a system constructed in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Turning again to the drawings,  FIGS. 2-8  illustrate a variety of semiconductor chips that may be placed on top of another chip in an MCP.  FIGS. 9-18  illustrate semiconductor chips, including chips like those depicted in  FIGS. 2-8 , in MCPs. 
     With reference first to  FIGS. 2 and 3 , indicated generally at  32  is a semiconductor device. Device  32  includes a plurality of conductive lines, like conductive lines  34 ,  36 . The conductive lines are formed on the surface  38  of a dielectric layer  40 , which in turn is formed on a semiconductor substrate  42 . The conductive lines can form a pattern of alternating lines and spaces, as shown. An internal circuit region  44  is formed in dielectric layer  40 . Conductive chip pads, like pads  46 ,  48 , are formed on dielectric layer  40  and connect to internal circuit portions (not depicted) of semiconductor device  32 . A passivation layer  50  is formed on dielectric layer  40 . 
     Openings, like openings  52 ,  54 , are formed in passivation layer  50  with opening  52  exposing a portion of chip pad  46  and opening  54  exposing a portion of conductive line  34 . Each of the chip pads, like chip pads  46 ,  48 , include a corresponding opening to expose the chip pads for connection to external circuitry. Additional openings, like opening  54 , are formed over at least some of the metal lines in a manner that will be described more fully herein. 
     The chip pads, like chip pads  46 ,  48 , may be formed in the same process step, or in a different step, as formation of the conductive lines, like lines  34 ,  36 . The conductive lines are electrically isolated from the chip pads. Conductive lines that provide power or ground connections in an MCP may be wider than other conductive lines. 
     In  FIG. 4 , indicated generally at  56  is another semiconductor chip according to the invention. Structure that corresponds to previously identified structure is either unnumbered or carries the same identifying number. In chip  56 , the conductive lines, like conductive lines  34 ,  36 , are formed on top of passivation layer  50  rather than on top of dielectric layer  40  as in  FIG. 3 . A resin layer  58  is formed on top of passivation layer  50  and includes openings, like openings  60 ,  62 , to expose the chip pads and parts of the conductive lines in the same manner as openings  52 ,  54  in  FIG. 3 . Resin layer  58  comprises a polymer layer including polyimide. 
     In chip  56 , the chip pads and conductive lines can be formed in different planes and in different process steps. To increase wire bonding efficiency and to prevent difficulties during wire bonding caused by the difference in height between the chip pads and the conductive lines, the height of the chip pads, like chip pad  46 , may be extended in a further process step to the level of dashed line  64  thereby bringing the upper surfaces of both the conductive lines and the chip pads to substantially the same plane. 
     The extension of the chip pads, like chip pad  46 , to the level of dashed line  64  may be accomplished in the same process step in which the conductive lines are formed thereby bringing the upper surfaces of both the conductive lines and the chip pads to substantially the same plane. For example, after the formation of the opening  52  as shown in  FIG. 3 , a blanket conductive layer (not shown) can be formed on passivation layer  50  and chip pad  46 . The conductive lines and an extended portion (not shown) of chip pad  46  can be formed by a conventional patterning process of the blanket conductive layer. The resin layer  58  is formed on top of passivation layer  50  and includes the openings, like opening  62  and upper portion of opening  60 , to expose the extended portion of the chip pads and parts of the conductive lines in the same manner as openings  52 ,  54  in  FIG. 3 . 
     In  FIG. 5 , indicated generally at  66  is another semiconductor chip according to the invention. Structure that corresponds to previously identified structure is either unnumbered or carries the same identifying number. In chip  66 , the conductive lines, like conductive lines  34 ,  36 , are at an angle relative to the generally rectangular shape of chip  66 . Lines  34 ,  36  may be placed at any angle, and may not even necessarily be linear—for example, one or more lines could be curved—so long as the lines are electrically isolated from the chip pads, like pads  46 ,  48 . 
     In  FIG. 6 , indicated generally at  68  is another semiconductor chip according to the invention. Structure that corresponds to previously identified structure is either unnumbered or carries the same identifying number. In chip  68 , the conductive lines, like conductive lines  34 ,  36 , are separated into two groups  70 ,  72 , with the groups being separated by a space indicated generally at  74 . As a result, lines  34 ,  36  are electrically isolated from collinear lines  76 ,  78 , respectively. As will be seen, this permits lines in each group, like lines  34 ,  36 , to propagate different signals because they are electrically isolated from one another. 
     In  FIG. 7 , indicated generally at  80  is another semiconductor chip according to the invention. Structure that corresponds to previously identified structure is either unnumbered or carries the same identifying number. In chip  80 , at least one of conductive lines, like  82 , and chip pad  46  are each connected to a conductive through-silicon via (TSV)  83 ,  84 , respectively, as are several other of the conductive lines and chip pads, although the chip pad connections are not visible in  FIG. 7 . Each conductive TSV is connected to a conductive pad, like pads  86 ,  88 . 
     The TSVs are each formed through dielectric layer  40  and semiconductor substrate  42  and thereby carry signals from the metal lines and chip pads to the conductive pads, like pads  86 ,  88 , on the underside of semiconductor chip  80 . As will be seen, this arrangement facilitates connections in an MCP. This approach could also be used in the embodiment of  FIG. 4 . 
     In  FIG. 8 , indicated generally at  90  is another semiconductor chip according to the invention. Structure that corresponds to previously identified structure is either unnumbered or carries the same identifying number. Semiconductor chip  90  has conductive lines laid out in a manner similar to semiconductor chip  68  in  FIG. 6 . Chip  90 , however, includes center chip pads, like chip pads  92 ,  94 . As the chip pads in the other embodiments do, the chip pads in chip  90  make electrical connections with circuitry internal to chip  90 . Unlike the other embodiments, however, each of the chip pads on chip  90  are electrically connected to a single corresponding conductive line, like chip pads  92 ,  94  are connected to lines  76 ,  34 , respectively. As can be seen, there are additional conductive lines that are not connected to chip pads. These additional unconnected lines are electrically isolated from the internal chip circuitry and from the chip pads. This arrangement provides for redistribution of the signals on the chip pads via the conductive line to which each pad is connected, as will be further described in connection with  FIG. 18 . 
     Indicated generally at  96  in  FIG. 9  is an MCP. The MCP includes a first semiconductor chip  98  and a second semiconductor chip  100 . Structure that corresponds to previously identified structure is either unnumbered or carries the same identifying number. Chip  98  is constructed similarly to chip  32  in  FIGS. 2 and 3 . Chip  100  is mounted on chip  98  via adhesive, and chip  98  is mounted on a substrate  102 , also using adhesive. A first side (not visible) of chip  98  is mounted on substrate  102 . Chip  100  is mounted on the second side  99  of chip  98 . 
     Chip  100  includes conductive pads as shown that are connected via wire bonds, like wire bond  104 , to conductive line  34 . A portion of conductive line  34  is exposed by an opening  106  etched into passivation layer  50  in the manner shown in  FIG. 3 . This permits wire bond  104  to be electrically connected to the conductive line by a bonding process. As a result, internal circuitry of chip  100  is electrically connected to conductive line  34  via a chip pad on chip  100  and wire bond  104 . This redistributes the connection point for the internal circuitry of chip  100 . 
     Another opening  108  over conductive line  34  provides access to the conductive line for bonding one end of another wire  110  to conductive line  34 . The other end of wire  110  is bonded to a terminal  112  on substrate  102 . Other terminals on chip  100  are bonded to other conductive lines via wire bonds, like wire bond  104 , as shown, and these other conductive lines are in turn bonded to terminals, like terminal  112  on substrate  102 , via wire bonds like wire bond  110 . In this manner, the connections to circuitry in chip  100  are redistributed to facilitate wire bonding in a manner that obviates problems associated with the length, height, and bonding angles of the conventional approach. Chip pads, or terminals, on first semiconductor chip  98  are connected to terminals, like terminal  114  on substrate  102 , via wire bonds like wire bond  225 . The terminals such as terminal  114  are also referred to herein as electrical contacts. 
     This approach provides for electrically connecting chip  100  and substrate  102  with wire bonds that have a length, height, and bonding angle similar to the wire bonds that connect the pads on chip  98  to the substrate. 
     Indicated generally at  118  in  FIG. 10  is an MCP. The MCP includes a first semiconductor chip  120 , a second semiconductor chip  122 , and a third semiconductor chip  124 . Structure that corresponds to previously identified structure is either unnumbered or carries the same identifying number. Chip  120  is constructed similarly to chip  98  in  FIG. 9 . And chips  122 ,  124  are mounted on chip  120  similarly to the way chip  100  is mounted on chip  98  in  FIG. 9 . 
     Chip  124  includes pads that are connected to metal lines in a manner similar to how the pads on chip  122  are connected to metal lines. For example, on chip  122  a wire bond  104  connects one of the pads on chip  122  to a conductive line  128 . Another wire bond  130  is connected to conductive line  128  through an etched opening  132 . The other end of wire bond  130  is connected to one of the terminals on substrate  102 . 
     Because each conductive line is isolated from every other conductive line, and from internal semiconductor circuitry, adjacent conductive lines, like lines  34 ,  128 , may be used to route connections from the pads on chips  122 ,  124 , respectively. In MCP  118 , every other conductive line is associated with connections from one of chips  122 ,  124 . In other words, if the conductive lines are consecutively numbered, the odd ones are connected to pads on one of the chips and the even ones are connected to pads on the other chip. 
     Indicated generally at  134  in  FIG. 11  is an MCP. The MCP includes a first semiconductor chip  136  and a second semiconductor chip  138 . Structure that corresponds to previously identified structure is either unnumbered or carries the same identifying number. Chip  136  is constructed similarly to chip  68  in  FIG. 6 . And chip  138  is mounted on chip  136  similarly to the way chip  100  is mounted on chip  98  in  FIG. 9 . 
     As can be seen, pads on one side of chip  138  are connected via wire bonds as previously described to adjacent lines in line group  70 , and the pads on the other side are connected via wire bonds to adjacent lines in line group  72 . Each of the lines to which a pad on chip  138  is connected is in turn connected via another wire bond to a terminal on substrate  102 . As a result, the pitch of the pads or, the number of pads along the edges of the second chip, may be increased because at least two sides of chip  136  may be used as signal paths via the metal line groups  70 ,  72 . 
     Indicated generally at  140  in  FIG. 12  is an MCP. The MCP includes a first semiconductor chip  142 , a second semiconductor chip  144 , and a third semiconductor chip  146 . Structure that corresponds to previously identified structure is either unnumbered or carries the same identifying number. Chip  142  is constructed similarly to chip  136  in  FIG. 11 . And chips  144  and  146  are mounted on chip  142  similarly to the way previously described chips are mounted on the first semiconductor chip. 
     In MCP  140  the pads on chip  144  are connected via wire bonds to conductive lines in group  70  in the manner previously described, and the pads on chip  146  are connected to the conductive lines in group  72 . The two groups of conductive lines are in turn connected via wire bonds to terminals on substrate  102 , also as previously described. This approach provides for a high density MCP. 
     Indicated generally at  148  in  FIG. 13  is an MCP. The MCP includes a first semiconductor chip  150  and a second semiconductor chip  152 . Structure that corresponds to previously identified structure is either unnumbered or carries the same identifying number. Chip  150  is constructed similarly to chip  98  in  FIG. 9 . Chip  152  is mounted on chip  150  using solder bumps  154 ,  156 , best seen in  FIG. 14 . Solder bump  154  is mounted on a chip pad  158  that is connected to internal circuitry of chip  152 . But bump  156  provides only structural support for chip  152 ; it is not connected to any internal chip circuitry. Both bumps  154 ,  156  are supported on metal line  34 , which carries whatever voltage appears on pad  158 . The pitch of the bumps on chip  152  is substantially the same as the pitch of the conductive lines, like conductive line  34 , on chip  150 . This approach facilitates use of flip chip bonding with the bumps being formed on chip  152 . As a result, there are no wire bonds connected to the second chip, thus eliminating disadvantages associated with use of wire bonds. 
     In an alternative approach (not shown) conducting bump  154  may be received completely within the opening in the passivation layer over conductive line  34  with the underside of chip  152  being supported on passivation layer  50 . This may require a thicker passivation layer than depicted in  FIG. 14 , but eliminates the need for a support bump, like bump  156 , because the chip is resting on and supported by passivation layer  50 . 
     In another alternative approach, the first semiconductor chip  150  can be mounted on the substrate  102  with its active surface, which includes chip pads, facing substrate  102 . In that structure, an insulating layer (not shown) can be formed on the surface opposite the active surface of the first semiconductor chip  150 , namely the exposed surface of the semiconductor substrate  42 . The conductive lines can be formed on the insulating layer (not shown). The first semiconductor chip  150  can be coupled to substrate  102  by flip chip bonding and the conductive lines can be used to form electrical connections between the second semiconductor chip  152  and the substrate  102 . The second semiconductor chip may be connected to the conductive lines in any manner described herein. 
     Indicated generally at  159  in  FIGS. 15 and 16  is an MCP. The MCP includes a first semiconductor chip  160  mounted on the substrate  102  with an adhesive layer  163  and a second semiconductor chip  162 . Structure that corresponds to previously identified structure is either unnumbered or carries the same identifying number. Both chips are constructed similarly to chip  80  in  FIG. 7  in that each has conductive TSVs, like TSV  166  in chip  160  and TSV  164  in chip  162 . 
     One end of TSV  164  is connected to a conductive pad  168  formed on chip  162 . Pad  168  is connected to internal circuitry of chip  162 . The other end of TSV  164  is connected to a redistributed pad  170 , which is in turn mounted on conductive line  34 . Alternatively, TSV  164  may be directly connected to conductive line  34  without the need for redistributed pad  170 . 
     The upper end of a TSV  166  (in chip  160 ) is connected to the underside of conductive line  34  with the lower end being connected to a terminal  172  formed on substrate  102 . As a result, an internal circuit connection in chip  162  is redistributed via pad  168 , TSV  164 , conductive line  34 , and TSV  166  to terminal  172  on substrate  102 . This approach obviates the need for any wire bonding. In other words, it provides an MCP without any wire bonds. The first semiconductor chip  160  is secured to substrate  102  with an adhesive layer  163 . 
     Indicated generally at  174  in  FIG. 17  is an MCP. The MCP includes a first semiconductor chip  176 , a second semiconductor chip  178 , and a third semiconductor chip  180 . Structure that corresponds to previously identified structure is either unnumbered or carries the same identifying number. Chips  176 ,  178  are constructed similarly to chip  98  in  FIG. 9 . Chips  176 ,  178  are substantially identical to one another and may comprise, e.g., memory chips. As can be seen, chip  178  is mounted on chip  176  with the centers of both chips offset from one another. This results in two sides of chip  178  lapping over two edges of chip  176  with substantial portions of the other two sides  182 ,  184  of chip  178  being set back from the other two edges of chip  176 . As a result, wire bond connections, like wire bond  110 , may be made between the conductive lines on chip  176  and the terminals on substrate  102 , like terminal  112 , and further wire bond connections, like wire bond  186 , may be made between the conductive lines on chip  178  and the conductive lines on chip  176 . It is of course possible to stack chips of different sizes with the larger chip preferably being beneath a smaller chip. 
     Chip  180 , which may be, e.g., an LSI circuit such as a processor, is mounted on chip  178  using adhesive. The pads on chip  180  are connected to conductive lines on chip  178  using wire bonds, like wire bond  188 . As a result, circuitry internal to chip  180  may be connected via wire bonds, like wire bond  188 , to the conductive lines on chip  178 . These conductive lines are connected via wire bonds, like wire bond  186 , to conductive lines on chip  176 , which are in turn connected via wire bonds, like wire bond  110 , to terminals, like terminal  112  on substrate  102 . 
     The terminals on chips  176 ,  178  are connected via wire bonds, like wire bonds  190 ,  192 , respectively, to terminals on substrate  102 . In an alternative embodiment (not shown) TSVs, like those shown in  FIGS. 7 ,  15 , and  16 , may be used to provide some or even all of the connections shown as wire bonds in  FIG. 17 . 
     Indicated generally at  194  in  FIG. 18  is an MCP. The MCP includes a first semiconductor chip  196  and a second semiconductor chip  198 . Structure that corresponds to previously identified structure is either unnumbered or carries the same identifying number. Chip  196  is constructed similarly to chip  90  in  FIG. 8 . Chip  196  includes a plurality of conductive chip pads, like pads  92 ,  94  disposed on an upper surface of chip  196  beneath chip  198 . These pads on chip  196  are disposed in two substantially parallel rows beneath chip  198  with pad  92  being in one row and pad  94  in the other. 
     Every other conductive line in each of groups  70 ,  72  is connected to one of the pads, like pads  92 ,  94 . Every other conductive line in each of groups  70 ,  72  is connected to a conductive pad, like pads  206 ,  208 , on the upper surface of chip  198  via wire bonds, like wire bonds,  230   a ,  230   b , respectively. Put differently, every even conductive line is connected to pads, like pads  92 ,  94 , on the upper surface of chip  196 , and every odd conductive line is connected to pads, like pads  206 ,  208 , on the upper surface of chip  198 , with the latter connections being made with wire bonds, like wire bonds  230   a ,  230   b.    
     Further wire bonds, like wire bonds  225 ,  220 , connect the conductive lines to terminals, like terminals  218 ,  210 , respectively, on substrate  102 . In an alternative embodiment (not shown), a chip smaller than chip  198  is mounted on chip  196  between the two rows of pads on chip  196 . In other words, the second chip does not cover the pads on the first chip. 
     Turning now to  FIG. 19 , indicated generally at  222  is a schematic diagram of a card constructed in accordance with the present invention. Card  222  may be, e.g., a multimedia card (MMC) or a secure digital card (SD). Card  222  includes a controller  224  and a memory  226 , which could be a flash, PRAM, or another type of non-volatile memory. A communication channel, indicated generally at  228 , permits the controller to provide commands to the memory and to transfer data into and out of memory  226 . Controller  224  and memory  226  may comprise an MCP in accordance with any of the previously described embodiments. The card  222  can have a larger density than conventional type. In the present invention, it is possible to remove interposer chips, so that card thickness can be reduced with respect to the conventional card having interposer chips. Additionally, the present invention can reduce defects from card caused by wire broken, so that reliability of card can be increased. 
     Considering now  FIG. 20 , indicated generally at  230  is a system constructed in accordance with the present invention. System  230  may be, e.g., a computer system, a mobile phone, an MP3 player, a GPS navigation device, a solid state disk (SSD), a household appliance, etc. System  230  includes a processor  232 ; a memory  234 , which could be a DRAM, flash, PRAM, or another type of memory; and an Input/Output Device  236 . A communication channel  238  permits the processor to provide commands to the memory to transfer data into and out of memory  234  via channel  238 . Data and commands may be transferred to and from system  230  via Input/Output device  236 . Processor  232  and memory  234  may comprise an MCP in accordance with any of the previously described embodiments. The present invention can make the stable system because the present invention can reduce defects caused by a broken wire.