Patent Publication Number: US-7915084-B2

Title: Method for making a stacked package semiconductor module having packages stacked in a cavity in the module substrate

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a divisional of co-pending U.S. patent application Ser. No. 11/381,683 filed May 4, 2006, which claims priority from U.S. Provisional Patent Application Ser. No. 60/678,553 filed May 4, 2005, which is hereby incorporated by reference herein. 
    
    
     BACKGROUND 
     This invention relates to stacked chip (stacked die) packages. 
     Increasingly, the semiconductor industry requires that packages have greater functionality in increasingly thin, small and compact package structures. There has been rapid progress in increasing the density of semiconductor devices in packages. In one approach, stacked chip scale package (SCSP) have been developed. These packages include two chips (or usually more than two chips), stacked on a substrate which has a chip mount area on the front surface and a solder ball pad area on the back surface. The chips are mounted using adhesive materials, and are electrically connected with the substrate using wire bonds which connect bond pads on the chip and bond fingers in a circuit pattern on the front surface of the substrate. Solder balls are mounted on the ball pads on the back surface of the substrate, for interconnection of the package with, for example, a motherboard. The die (chips), the wires, and other features on the front side of the substrate are encapsulated with an encapsulation material. 
     These features of such a conventional SCSP are shown diagrammatically by way of example in  FIG. 1 , in sectional view. The package includes a package substrate having a die mount region on a front surface, and second level interconnect solder ball pads on a back surface. The illustrated package includes six die (semiconductor chips), including two bare silicon spacer die, stacked and mounted on the die mount region of the front surface of a substrate. 
     The die are electrically interconnected to the substrate by wire bonds connecting bond pads on the respective die (die pads) to bond sites on a circuit pattern on the front surface of the substrate. Solder balls are mounted on ball pads on the back surface of the substrate, for second level interconnection of the package with, for example, a motherboard. 
     The lowermost (first) active die in the stack is affixed on a die mount region of the front surface of the substrate using an adhesive material, which may be a die attach epoxy, for example, or an adhesive film. A second active die is affixed onto the first die, again using an adhesive. A first spacer is affixed onto the first die, using an adhesive; the spacer may be, for example, a “dummy” die, cut from a silicon wafer having no circuitry, or it may be a glass chip, for example. A third active die is stacked over the spacer, and affixed using an adhesive. The third active die is as wide as or wider than the second active die, and the spacer is employed between the second active die and the third active die, so that the marginal parts of the third active die overhang the wire loops connecting the second active die to the substrate. The spacer must have a footprint selected to prevent interference by the spacer with the connection of the wire loops with the die pads, and must have a thickness selected to provide relief for the wire loop height (plus some tolerance). A second spacer is affixed onto the third active die, using an adhesive; this spacer may also be, for example, a “dummy” die. A fourth active die is stacked over the second spacer, and affixed using an adhesive. The fourth active die in this example is wider than the third active die, and the second spacer is employed between the third active die and the fourth active die, so that the marginal parts of the third active die overhang the wire loops connecting the third active die to the substrate. As noted above, this package when complete includes six-stacked chip, all of which contribute to the overall thickness of the package, but only four of the die have an electrical function. Accordingly, in such a conventional package the electronic density of the package, and the thinness profile, are compromised. 
     SUMMARY 
     This invention is directed to a package structure having stacked chips in a unit package which has a chip-mount area on the front and back surfaces of the substrate. The packages according to the invention provide for increased chip capacity in a package having a thin profile. 
     According to the invention a stacked die chip scale package module includes a stacked die assembly mounted within a cavity in a module substrate. In some embodiments one or more of the die are stacked on a front side of a stacked die assembly substrate, and the stacked die assembly substrate is inverted in the cavity and the substrate is electrically interconnected to a front side of the module substrate; one or more die are stacked on the back side of the stacked die assembly substrate, and are interconnected by wire bonds to the front side of the module substrate. In some embodiments, the cavity is covered by a heat sink, and the stacked die assembly is mounted onto the heat sink. 
     In one general aspect, the invention features a multi-chip module including: a stacked die assembly including an assembly substrate having a front side and a back side and having at least a first die mounted onto and electrically connected to the front side constituting an assembly package, the stacked die assembly further including at least a first additional die mounted onto the back side of the assembly substrate; and a module substrate having a front side and a back side, the module substrate having an opening therethrough having a length and width at least sufficient to accommodate a length and width of the assembly package; wherein the stacked die assembly is situated so that at least part of the assembly package is within the opening. The first die in the assembly package may be wire bonded to the assembly substrate, or may be mounted by flip chip interconnect to the assembly package. The first additional die may be wire bonded to the module substrate, or may be mounted by flip chip interconnection to the stacked die assembly substrate. In some embodiments a second die is mounted (and in some embodiments two or more die are mounted) over the first die in the assembly package; in such embodiments the first die may be wire bonded to the stacked die assembly package, or mounted by flip chip interconnect. In some embodiments a second additional die is mounted (and in some embodiments two or more additional die are mounted) over the first additional die; in such embodiments the first additional die may be wire bonded to the stacked die assembly package, or mounted by flip chip interconnect to the stacked die assembly package. 
     In some embodiments the die and interconnects on the front side of the stacked die assembly substrate are encapsulated or molded. 
     In some embodiments a support spans the opening in the module substrate, and the inverted package is mounted onto the support. In some such embodiments the support constitutes a cover over the entire opening at the back side of the module substrate. 
     In another general aspect the invention features a semiconductor multi-chip module substrate, including a dielectric layer and at least one patterned metal layer and having a front side and a back side, the substrate having an opening therethrough, the opening having a length and width sufficient at least to accommodate a footprint of a selected semiconductor package. In some embodiments the substrate comprises a two-metal layer substrate. In some embodiments a support spans the opening at the back side, and in some such embodiments the support covers the opening. In some embodiments the support comprises a metal sheet; the metal sheet may assist in heat dissipation or, where the metal sheet is electrically conductive and where the sheet is connected to a reference electrical potential (“ground” potential) the metal sheet may serve as an electromagnetic shield. 
     In another general aspect, methods for making the module include: providing a stacked die assembly substrate; affixing at least a first die on a front side of the assembly substrate and electrically connecting the die to sites at the front side of the assembly substrate to form a package; providing a module substrate having a front side and a back side and an opening through, the opening having a length and width at least as great as the length and width of the package; reversibly affixing the module substrate onto a stage; inverting the package and situating the package at least partly within the opening; mounting at least a first additional die at the back side of the assembly substrate to form a stacked die assembly, and electrically connecting the additional die to sites at the front side of the module substrate; encapsulating the stacked die assembly and interconnections and the front side of the module substrate; removing the module from the stage; and attaching second-level interconnect solder balls at sites in the back side of the module substrate. 
     In some embodiments the step of situating the package includes removably affixing a top surface of the package to the stage within the opening. In some embodiments, the step of providing the substrate includes providing a support spanning the opening at the back side of the substrate; in some such embodiments the step of situating the package includes affixing a top surface of the package to the support within the opening. 
     Because the thickness of the die on the front side of the stacked die assembly substrate are accommodated at least in part within the cavity, the thickness of the module can be made less than if the die are stacked serially upon one surface of the substrate. Also, in some assemblies, the die can be stacked according to their relative sizes, so that the need for spacers between adjacent die can in some assemblies be avoided, further reducing the thickness of the module. 
     In embodiments in which the die on the front side of the stacked die assembly are encapsulated, the assembly package can be tested prior to assembly, and only assembly packages that test as “good” are used in making modules. This results in improved module yield. 
     In embodiments in which the stacked die assembly is mounted on a heat sink at the back side of the module, so that a surface of the heat sink is exposed there, improved heat dissipation from the die stack is provided according to the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagrammatic sketch in a sectional view showing a conventional stacked chip scale package structure. 
         FIG. 2  is a diagrammatic sketch in a sectional view showing a multi-chip module according to an embodiment of the invention. 
         FIG. 3A  is a diagrammatic sketch in a sectional view showing a substrate for a stacked die assembly for use in a multi-chip module as in  FIG. 2  according to an embodiment of the invention. 
         FIGS. 3B and 3C  are diagrammatic sketches in a plan view showing a substrate as in  FIG. 3A . 
         FIG. 4A  is a diagrammatic sketch in a sectional view showing a module substrate for use in a multi-chip module as in  FIG. 2  according to an embodiment of the invention. 
         FIG. 4B  is a diagrammatic sketch in a plan view showing a substrate as in  FIG. 4A . 
         FIG. 5  is a diagrammatic sketch in a sectional view showing a multi-chip module according to another embodiment of the invention. 
         FIG. 6  is a diagrammatic sketch in a sectional view showing a multi-chip module according to yet another embodiment of the invention. 
         FIGS. 7A-7E  are diagrammatic sketches in sectional view showing steps in assembly of a multi-chip module as in  FIG. 2  according to an embodiment of the invention. 
         FIG. 8  is a diagrammatic sketch in a sectional view showing a step in manufacture of a multi-chip module according to yet another embodiment of the invention. 
         FIG. 9  is a diagrammatic sketch in a sectional view showing a multi-chip module according to yet another embodiment of the invention. 
         FIG. 10  is a diagrammatic sketch in a sectional view showing a step in manufacture of a multi-chip module according to yet another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The invention will now be described in further detail by reference to the drawings, which illustrate alternative embodiments of the invention. The drawings are diagrammatic, showing features of the invention and their relation to other features and structures, and are not made to scale. For improved clarity of presentation, in the FIGs. illustrating embodiments of the invention, elements corresponding to elements shown in other drawings are not all particularly renumbered, although they are all readily identifiable in all the FIGs. 
       FIG. 1  shows a conventional stacked die chip package structure  101 , including four semiconductor die  112 ,  114 ,  116 ,  118  mounted in a stack over, and electrically connected by wire bonds  132 ,  134 ,  136 ,  138  to, a substrate  110 . The stacked die and the wire bond connections and the die mount side of the substrate are protected by an encapsulation  147 , and solder balls  148  are provided on the opposite side of the substrate for second-level connection of the package  101  to underlying circuitry such as, for example, a motherboard. The substrate  110  in this example is a laminate substrate having two patterned metal layers separated by a dielectric layer, and connected to one another by vias through the dielectric layer. Each patterned metal layer is covered by a dielectric solder mask, having openings that expose sites on the metal layer for electrical connection of wire bonds or solder balls or other features. In the example illustrated in  FIG. 1 , a first die  112  is affixed using a die attach adhesive  111  onto a die attach region of the die mount side of the substrate  110 . The active side of the die faces away from the substrate, and the die  112  is electrically connected to the substrate by wire bonds  132  running from interconnect pads on the active side of the die to bond pads in the metal layer at the die mount side of the substrate. A second die  114  is affixed using a die attach adhesive  113  onto a die attach region of the active side of the first die  112 , inboard from the die pads. The second die in this example has a smaller footprint (length and/or width) than the first die, so that the second die does not interfere with the wire bonds  132 . The active side of the first die typically has a passivation layer, and the adhesive  113  is a dielectric adhesive, so that the first and second die are electrically insulated from one another. The active side of the second die also faces away from the substrate, and the die  114  is electrically connected to the substrate by wire bonds  134  running from interconnect pads on the active side of the second die to bond pads in the metal layer at the die mount side of the substrate. A third die  116  is mounted over the second die; in this example the third die has a footprint the same as that of the second die and, accordingly, a first spacer is mounted between the second and third die to provide relief for the wire bonds  134 . The first spacer  122  in this example is a “dummy” die, and is affixed using a die attach adhesive  121  onto a die attach region of the active side of the second die  114 , inboard from the die pads. The first spacer in this example has a smaller footprint (length and/or width) than the second die, so that the third die does not interfere with the wire bonds  134 . The active side of the second die typically has a passivation layer, and the adhesive  121  is a dielectric adhesive, so that the second die and the first spacer are electrically insulated from one another. The third die  116  is affixed using an adhesive  123  onto the first spacer  122 . The active side of the third die also faces away from the substrate, and the die  116  is electrically connected to the substrate by wire bonds  136  running from interconnect pads on the active side of the second die to bond pads in the metal layer at the die mount side of the substrate. A fourth die  118  is mounted over the third die; in this example the fourth die has a larger footprint than the second die and, accordingly, a second spacer is mounted between the third die and the fourth die to provide relief for the wire bonds  136 . The second spacer  126  in this example is a “dummy” die, and is affixed using a die attach adhesive  123  onto a die attach region of the active side of the third die  116 , inboard from the die pads. The second spacer in this example has a smaller footprint (length and/or width) than the third die, so that the fourth die does not interfere with the wire bonds  136 . The active side of the third die typically has a passivation layer, and the adhesive  125  is a dielectric adhesive, so that the third die and the second spacer are electrically insulated from one another. The fourth die  118  is affixed using an adhesive  127  onto the second spacer  126 . The active side of the fourth die also faces away from the substrate, and the die  118  is electrically connected to the substrate by wire bonds  138  running from interconnect pads on the active side of the second die to bond pads in the metal layer at the die mount side of the substrate. 
     A conventional stacked die package structure as in  FIG. 1  is conventionally made by providing the substrate, mounting the first die on the substrate, mounting the second die on the first die, forming wire bonds to connect the first and second die to the substrate, mounting the first spacer on the second die, mounting the third die on the first spacer, forming wire bonds to connect the third die to the substrate, mounting the second spacer on the third die, mounting the fourth die on the second spacer, forming wire bonds to connect the fourth die to the substrate, forming the encapsulation, and affixing the second level interconnect solder balls. Testing of bare die is ordinarily not preferred, particularly where the die has a high i/o density and small die pads, as contact of the testing probes with the die pads can damage the pads. Additionally, testing of interconnected die on a substrate may be impractical unless the die and, particularly, the wire bonds, are protected by molding or encapsulation. Consequently, the die in a package as in  FIG. 1  cannot be tested until the package is complete at least through the encapsulation step. If any one of the four die is defective, then the package must be discarded even though the remaining die be acceptable. Considerable waste results, both of acceptable die in rejected packages, and of manufacturing resources. 
       FIG. 2  shows a module  201  according to an embodiment of the invention, in a diagrammatic sectional view. The construction of the module may be well understood by reference to  FIGS. 3A-3C , which show part of the stacked die assembly, which is defined as an assembly with one die attached directly on top of another die. The construction of the module may also be well understood by reference to  FIGS. 4A and 4B , which show the module substrate having a cavity to accommodate the stacked die assembly; and  FIGS. 7A-7E , which show steps in the construction of the module. 
     The module  201  in the example shown in  FIG. 2  includes a substrate  401  having an opening (cavity) and a support  460  spanning the opening (shown in greater detail in  FIG. 4A ); and a stacked die assembly mounted on the support  460  (including an inverted package  701  affixed using an adhesive  462  to the support, and additional die  416  and  418  stacked over the stacked die package). The package  701  is a stacked die package (shown in greater detail in  FIG. 7A ), having two die, one stacked over the other, and both die electrically connected to a package substrate (shown in greater detail in  FIG. 3A ). The package  701  is encapsulated, and is electrically connected with the module substrate  401  by wire bonds  232  connecting bond sites on the package substrate with bond pads on the assembly interconnect side (the “front” or “upper” side) of the module substrate. The first additional die  416  is affixed using an adhesive  435  to the land side of the package substrate, and the second additional die  418  is affixed using an adhesive  437  onto a die attach region of the active side of the first additional die  416 , inboard from the die pads. The additional die  416 ,  418  are electrically connected with the module substrate  401  by wire bonds  236 ,  238  connecting bond pads on the die with bond pads on the front side of the module substrate. The stacked die assembly, the wire bonds, and the assembly interconnect side (the “front” or “upper” side) of the substrate are protected by an encapsulation  247 . Solder balls  448  are provided on ball pads on the side of the module substrate  401 , opposite the front side (the “back” or “lower” side), for second-level interconnection to underlying circuitry (such as, for example, a printed circuit board such as a motherboard) in a device in which the module is used (such as, for example, a computer, a mobile computing or telecommunications device, or the like). 
     Referring now to  FIGS. 4A and 4B , a module substrate  301  according to an embodiment of the invention is shown in a plan view of the front side ( FIG. 4B ) and in a sectional view ( FIG. 4A ). The module substrate in this example is a laminate substrate having two metallizations or patterned metal layers  421  (at the front side of the substrate) and  423  (at the back side) separated by a dielectric layer  412  and connected by vias  422  through the dielectric layer. Solder masks  425 ,  427  covering the metal layers  421 ,  423  have openings exposing sites on the metal layers for electrical connection, including for example wire bond sites  432 ,  436 ,  438  for connection of wire bonds  232 ,  236 ,  238  on the front side and ball pads on the back side for attachment of second level interconnects such as solder balls  448 . The module substrate  401  according to this aspect of the invention has an opening  470  formed entirely through the upper (front side) metal layer and the dielectric, and the lower (back side) metal layer. A support  460  is in direct contact with the dielectric layer  412  outside of the opening and spans the opening at the back side, and is affixed, using an adhesive  462 , at a margin of the opening. In this example the support  460  is a heat dissipation member (heat sink), which may be a metal sheet, and in this example it covers the opening on the lower (back) side. The front side of the substrate  401 , viewed in plan as in  FIG. 4B , is provided with bond fingers  432 ,  436 ,  438  for electrical connection by wire bonds  232 ,  236 ,  238  with the various die and the package substrate in the stacked die assembly. 
       FIGS. 3A ,  3 B and  3 C show an example of a substrate  301  for the stacked die assembly. The stacked die assembly substrate in this example includes a dielectric layer  312 , with metallizations (patterned metal circuitry)  321 ,  323  at both a front side  302  and a back side  304 , as shown in a sectional view in  FIG. 3A , and in plan views in  FIGS. 3B and 3C . Solder masks  325 ,  327  covering the metal layers  421 ,  423  have openings exposing sites on bond fingers in the metal layers for electrical connection, including for example wire bond sites  332  on the front side for connection of wire bonds  736 ,  738  from the die  716 ,  718  and bond pads  334  on the back side for connection of wire bonds from the package substrate  301  to the module substrate  401 . 
     The module substrate is shown for purposes of illustration as being symmetrical in transverse sectional view; that is, the opening through the module substrate appears in the drawings to be centrally located in the substrate. This is not necessary; the opening can be formed toward a side or a corner of the substrate and, in embodiments where additional die have interconnect pads asymmetrically arranged, an asymmetrical arrangement of bond pads on the module substrate may be preferred and, accordingly, the opening may be situated so that there is a greater area of module substrate adjacent one or two sides of the opening for additional bond pads and circuitry. 
     The stacked die package  701  in the stacked die assembly as appears in  FIG. 2  is shown in detail in  FIG. 7A . The stacked die package  701  includes a substrate generally as described above, including a dielectric layer  312 , with patterned metal circuitry  321 ,  323  at both a front side  302  and a back side  304 , as shown in a sectional view in  FIG. 3A , and in plan views in  FIGS. 3B and 3C . Solder masks  325 ,  327  covering the metal layers  421 ,  423  have openings exposing sites on bond fingers in the metal layers for electrical connection, including for example wire bond sites  332  on the front side for connection of wire bonds  736 ,  738  from the die  716 ,  718  and bond pads  334  on the back side for connection of wire bonds from the package substrate  301  to the module substrate  401 . A first die  716  is affixed using an adhesive  715  to a die mount region of the front side of the substrate  301 , and is electrically connected to the substrate by wire bonds  736  from pads on the first die to wire bonds sites  332  at the front side of the substrate  301 . A second die  718  is affixed using an adhesive  717  to a die mount region of the active side of the substrate first die  716 , inboard of the die pads on the first die, and is electrically connected to the substrate by wire bonds  738  from pads on the second die to wire bonds sites  332  at the front side of the substrate  301 . The die and the wire bonds and the die mount side of the substrate are enclosed by an encapsulation  747 , which has a surface defining an upper side  746  of the package  701 . The package shown in these examples is saw- or punch-singulated; that is, the package is shown having been made as a strip or array of packages, all of which were covered with the encapsulant and then separated by cutting through the substrate and the encapsulation. Alternatively, the package could be molded. 
     Referring now to  FIGS. 7A-7E , a module as in  FIG. 2  is made by providing a stacked die assembly substrate as in  FIGS. 3A-3C , for example, and stacking die on a die mount region of the front surface, wire bonding the die to the front surface of the stacked die substrate, and encapsulating the stacked die and the wires, to make a stacked die chip scale package  701  as shown in  FIG. 7A . This may be provided as a standardized package. The packages can be tested prior to assembly in the module, and packages not meeting performance specifications can be discarded, so that only packages  701  testing as “good” are used in the assemblies. 
     Then, as shown in  FIG. 7B , a module substrate  401  having a cavity (as shown for example in  FIGS. 4A and 4B ) is provided, and is removably affixed to a stage represented at  402 . An adhesive material  732  is deposited on the support  460 , and the stacked die ship scale package as shown for example in  FIG. 7A  is inverted and inserted into the cavity and placed upon a surface  731  of the adhesive material  732 . The package  701  is said herein to be “inverted” in the sense that the die mount (front) side of the package substrate  301  faces in a direction opposite the assembly interconnect (front) side of the module substrate  401 . That is, the land side (back side) of the package substrate  301 —and, accordingly, the back side of the package  701 —faces away from the support  460 , and the surface of the encapsulation  747  (the “upper” side  746  of the package  701  as viewed in  FIG. 7A ) faces downward toward the support when inverted, and the upper side  746  contacts the surface  731  of the adhesive material  732 . The adhesive is then cured as may be appropriate, as shown at  462  in  FIG. 7C . Where a die mount adhesive is applied in a liquid or paste form, a fillet  733  is typically formed at the edges of the package surface  746  of the package molding. The package  701  is further depicted as mounted to and directly supported by the support  460  in  FIG. 7C . 
     Then the mounted package  701  is electrically connected to the module substrate  401  by wire bonds  232  connecting bond pads on the land side  304  of the package with bond pads  432  on the assembly interconnect side of the substrate  401 . Then a first additional die  416  is mounted using an adhesive  435  on the land side  304  of the package  701 , and the first additional die  416  is electrically connected to the module substrate  401  by wire bonds  236  connecting pads on the die  416  with bond pads  436  on the assembly interconnect side of the substrate; and a second additional die  418  is mounted using an adhesive  437  on the active side of the first additional die  416  inboard of the die pads, and the second additional die  418  is electrically connected to the module substrate  401  by wire bonds  428  connecting pads on the die  418  with bond pads  438  on the assembly interconnect side of the substrate 
     Then, one or more additional die (two, in this example) are mounted over a die attach region of the back side (upward-facing in  FIGS. 2 ,  7 C,  7 D,  7 E, for example) of the inverted stacked die assembly substrate  301 , and the die are interconnected by wire bonding to bond fingers on the front side of the module substrate. This completes the stacked die assembly, in situ in the module substrate cavity. Referring now to  FIG. 7D , the first additional die  416  is affixed using an adhesive  435  to the land side of the package substrate, and the second additional die  418  is affixed using an adhesive  437  to a die attach region of the active side of the first additional die  416 , inboard from the die pads. The additional die  416 ,  418  are electrically connected with the module substrate  401  by wire bonds  236 ,  238  connecting bond pads on the die with bond pads  436 ,  438  on the front side of the module substrate. The stacked die assembly, the wire bonds, and the assembly interconnect side (the “front” or “upper” side) of the substrate are protected by an encapsulation  247 . This results in the structure shown in  FIG. 7D . The module shown in these examples is saw- or punch-singulated; that is, the module is shown having been made as a strip or array of modules, all of which were covered with the encapsulant and then separated by cutting through the module substrate and the encapsulation. Alternatively, the package could be molded. This structure is removed from the stage  402 , and it can be tested, prior to attachment of solder balls  448  on ball pads  440  on the side of the module substrate  401 , opposite the front side (the “back” or “lower” side), as shown in  FIG. 7E , for second-level interconnection to underlying circuitry (such as, for example, a printed circuit board such as a motherboard) in a device in which the module is used (such as, for example, a computer, a mobile computing or telecommunications device, or the like). 
     In some embodiments of the invention, no support is provided spanning the cavity. The method for making modules according to such embodiments is similar to that described with reference to  FIGS. 7A-7E , except that, as shown in  FIG. 8 , the substrate is provided with an opening but without the support ( 460  in  FIG. 7B ). The substrate is mounted (removably affixed) on the stage  802 , and the assembly package  701  is mounted on the stage  802  within the opening. Following steps as described for example with reference to  FIGS. 7C and 7D , the assembly is removed from the stage  802 , and the structural integrity is maintained by the module encapsulation. 
     Various stacked die assembly configurations are possible according to the invention, and more than one stacked die substrate may be mounted within the cavity in the module substrate, as shown for example in  FIGS. 5 and 6 . 
       FIG. 5  shows a module according to the invention, having two stacked die assemblies  502 ,  504  mounted side-by-side on a support  460  in a cavity in a module substrate  401 . Each stacked die assembly  502 ,  504  includes an inverted stacked die package, constructed generally as described above with reference to  FIGS. 3A-3C  and  7 A, mounted using an adhesive  562 ,  564  onto the support  460 ; the stacked die assembly substrates are connected to one another by wire bonds  537 , and each package is electrically connected to the module substrate by wire bonds  532 ,  534  connecting bond pads  334  on the package substrates with bond pads  432  on the assembly interconnect side of the module substrate  401 . In this example an additional die  573 ,  574  is affixed using an adhesive  533 ,  544  onto the land side of the stacked die assembly substrate, and each additional die  573 ,  574  is electrically connected to the module substrate by wire bonds  536 ,  538  connecting pads on the die to bond sites on the assembly interconnect side of the module substrate  401 . The stacked die assemblies, the wire bonds, and the assembly interconnect side (the “front” or “upper” side) of the substrate are protected by an encapsulation  547 , and solder balls  448  are attached on ball pads  440  on the side of the module substrate  401 , opposite the front side (the “back” or “lower” side), for second-level interconnection to underlying circuitry (such as, for example, a printed circuit board such as a motherboard) in a device in which the module is used (such as, for example, a computer, a mobile computing or telecommunications device, or the like). 
       FIG. 6  shows a module according to the invention, having two inverted stacked die packages  602 ,  604  mounted side-by-side on a support  460  in a cavity in a module substrate  401 . Each stacked die package  502 ,  504 , constructed generally as described above with reference to  FIGS. 3A-3C  and  7 A, is mounted using an adhesive  662 ,  664  onto the support  460 ; and each package is electrically connected to the module substrate by wire bonds  532 ,  534  connecting bond pads  334  on the package substrates with bond pads  432  on the assembly interconnect side of the module substrate  401 . In this example, a first additional die  616 , having a large footprint, is mounted over both stacked die packages  602 ,  604  and is affixed onto the land sides of both stacked die packages using adhesives  635 ,  637 . The first additional die  616  is electrically connected to the module substrate by wire bonds  632 ,  636  connecting pads on the die to bond sites  436  on the assembly interconnect side of the module substrate  401 . A second additional die  618 , having a larger footprint than the first additional die  616 , is mounted using an adhesive  639  on the active side of the first additional die  616 . The second additional die  618  is electrically connected to the module substrate by wire bonds  634 ,  638  connecting pads on the die to bond sites  438  on the assembly interconnect side of the module substrate  401 . The stacked die packages, the additional die, the wire bonds, and the assembly interconnect side (the “front” or “upper” side) of the substrate are protected by an encapsulation  647 , and solder balls  448  are attached on ball pads  440  on the side of the module substrate  401 , opposite the front side (the “back” or “lower” side), for second-level interconnection to underlying circuitry (such as, for example, a printed circuit board such as a motherboard) in a device in which the module is used (such as, for example, a computer, a mobile computing or telecommunications device, or the like). 
     Other embodiments and variations are contemplated by the invention. 
     For example, other substrate types than the two-metal layer laminate substrates shown in the FIGs. can be employed according to the invention as the module substrate and/or as the stacked die package substrate or stacked die assembly substrate. Suitable substrates include tape substrates having one or two metal layers; laminate substrates having two, three or more metal layers; build-up substrates having two, four, or six or more metal layers; substrates having organic polymer dielectric layers or silicon dielectric layers; and others. 
     And, for example, one or more of the die may be mounted by flip-chip interconnection. Flip chip interconnection is well-known; generally, a flip chip is oriented with the active side of the die facing toward the mounting surface (rather than facing away from the mounting surface, as in wire bond interconnection), and electrical connection is made by balls or bumps (such as solder balls or bumps, or gold stud bumps) attached to pads on the die and to complementary sites on the electrical circuitry at the mounting surface. Particularly, for example, in the stacked die package according to the invention, a first die may be mounted onto the front side of the package substrate by flip chip interconnection, and a second (and subsequent) die in the stack may be attached using an adhesive to the backside of the first die, and electrically connected to the package substrate by wire bonding. And, for example, a first additional die may be mounted onto the land side (back side) of the package substrate by flip chip interconnection, and a second (and subsequent) additional die may be attached using an adhesive to the backside of the first additional die, and electrically connected to the module substrate by wire bonding. 
     Referring now to  FIG. 9 , for example, an assembly package  901  is similar to the assembly package  701 , except that in the assembly package  901  the first die is a flip chip die. In this example the stacked die assembly substrate is constructed generally as described with reference to  FIGS. 3A ,  3 B,  3 C. The first die  916  is oriented with the active side facing the substrate and is electrically connected to the front side of the assembly substrate by balls or bumps  936  attached to pads in the active side of the die and joined to interconnect sites on the patterned metal layer  321  at the front side of the substrate. In this example an underfill  915  protects the interconnections. The second die  918  is affixed to the backside of the first die using an adhesive  917 , with the active side of the second die facing away from the substrate, and the second die is connected to the substrate by wire bonds  938  connecting pads on the die with bond sites  332  on the front side of the substrate. An encapsulation  947  encloses the die, the sires, and the front side of the substrate, having a surface  946  defining a top surface of the package. 
     Referring now to  FIG. 10 , for example, an assembly is shown at a stage of manufacture of a module in which the first additional die on the stacked die assembly is a flip chip die. The module assembly with the assembly package  701  mounted on the support is generally as described with reference to  FIG. 7C . A first additional die  1016  is oriented with the active side facing the assembly substrate and is electrically connected to the front side of the assembly substrate by balls or bumps  1036  attached to pads in the active side of the die and joined to interconnect sites on the patterned metal layer  332  at the back side of the assembly substrate. In this example an underfill  1015  protects the interconnections. The second die  1018  is affixed to the backside of the first die using an adhesive  1017 , with the active side of the second die facing away from the assembly substrate, and the second die is connected to the module substrate  401  by wire bonds  1038  connecting bond sites  332  on the front side of the assembly substrate with bond pads  432  on the front side of the module substrate. 
     And, for example, where adjacent stacked die in a stacked die package or over the package substrate in a module according to the invention are wire bonded, a spacer may be provided between adjacent die, to prevent interference of a second die with wire bonds on a first die. 
     And, for example, the package that is mounted in the cavity according to the invention may have more than two stacked die (as shown in most of the FIGs.), or only one die. And there may be more than one additional die stacked over the package substrate; or there may be more than two additional die stacked over the package substrate. 
     Other embodiments are within the following claims.