Abstract:
A method including forming a first portion of a build-up carrier on at least one first die, the at least one first die; coupling at least one second die to the first portion of the build-up carrier, the at least one second die separated from the first die by the at least one layer of conductive material disposed between layers of dielectric material; and after coupling the at least one second die to the first portion of the build-up carrier, forming a second portion of the build-up carrier on the at least one second die. An apparatus including a build-up carrier including including alternating layers of conductive material and dielectric material and at least two dice therein in different planes of the build-up carrier.

Description:
BACKGROUND 
       [0001]    1. Field 
         [0002]    Packaging for microelectronic devices. 
         [0003]    2. Description of Related Art 
         [0004]    Microelectronic packaging technology, including methods to mechanically and electrically attach a silicon die (e.g., a microprocessor) to a substrate or other carrier continues to be refined and improved. Bumpless Build-Up Layer (BBUL) technology is one approach to a packaging architecture. Among its advantages, BBUL eliminates the need for assembly, eliminates prior solder ball interconnections (e.g., flip-chip interconnections), reduces stress on low-k interlayer dielectric of dies due to die-to-substrate coefficient of thermal expansion (CTE mismatch), and reduces package inductance through elimination of core and flip-chip interconnect for improved input/output (I/O) and power delivery performance. 
         [0005]    With shrinking electronic device sizes and increasing functionality, integrated circuit packages will need to occupy less space. One way to conserve space is to combine a device or package on top of a package. Current ways of integrating second devices (e.g., secondary dice) vertically to, for example, a system on chip (SOC) package is either package on package (POP) or through silicon via (TSV) integration. Both of these integration techniques require additional processing to attach the secondary die/module on top of the SOC package. The additional processing eventually creates assembly challenges. For example, in the case of a customer-owned POP (COPOP), the SOC package must be formed flat enough during the surface mount technology (SMT) reflow for the POP package to be properly soldered to the pad which drives process/material stackup characterization needed to achieve the desired outcome and also typically the size of the package is limited to small package sizes (e.g., a package size 8×8 square millimeter (mm 2 ) to 12×12 mm 2 ). While in the TSV scenario, it generally requires a thermal compression bonding (TCB) process which is not a very mature technology resulting in a slow throughput and assembly and reliability challenges. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  shows a cross-sectional view one embodiment of a portion of a microelectronic package including a primary die and two secondary dice in a build-up carrier. 
           [0007]      FIG. 2  shows a cross-sectional exploded side view of a sacrificial substrate with sacrificial copper foils attached to opposite sides thereof. 
           [0008]      FIG. 3  shows the structure of  FIG. 2  following the introduction of secondary dice on a surface of a copper foil and a dielectric layer over the secondary dice in a process of forming a build-up carrier. 
           [0009]      FIG. 4  shows the structure of  FIG. 3  following the patterning of electrically conductive vias to contact points and a first electrically conductive layer or line on the dielectric layer. 
           [0010]      FIG. 5  shows the structure of  FIG. 4  following the introduction of a dielectric layer on the first conductive layer and electrically conductive vias to the first conductive layer and contact lands on the dielectric layer. 
           [0011]      FIG. 6  shows the structure of  FIG. 5  following the patterning of conductive lands on the dielectric layer. 
           [0012]      FIG. 7  shows the structure of  FIG. 6  following the attachment of a primary die on the dielectric layer. 
           [0013]      FIG. 8  shows the structure of  FIG. 7  following the introduction of a dielectric layer over the primary die. 
           [0014]      FIG. 9  shows the structure of  FIG. 8  following the formation of openings in the dielectric layer to contact points on the die and the contact lands. 
           [0015]      FIG. 10  shows the structure of  FIG. 9  following the introduction of an electrically conductive material in the vias and the patterning of an electrically conductive layer or line on the dielectric as well as the introduction of a dielectric layer on the electrically conductive layer and the formation of openings therein. 
           [0016]      FIG. 11  shows the isolation of one package from the sacrificial substrate, the package including patterned contacts for a surface mount application. 
           [0017]      FIG. 12  illustrates a schematic illustration of a computing device. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]      FIG. 1  shows a cross-sectional view of a microelectronic package according to one embodiment. As illustrated in  FIG. 1 , microelectronic package  100  utilizes bumpless build-up layer (BBUL) technology. Microelectronic package  100  includes carrier  120 . For explanatory purposes, carrier  120  will be described with reference to two portions, portion  1200 A and portion  1200 B. It is appreciate that together portion  1200 A and portion  1200 B form a single integrated carrier. 
         [0019]    Referring to  FIG. 1 , portion  1200 A of carrier  120  includes primary die  110 , such as a microprocessor die or a system on chip (SOC) die, embedded in portion  1200 A device side up (as viewed). In one embodiment, die  110  is a silicon die or the like having a thickness of approximately 150 micrometers (μm). In another example, die  110  can be a silicon die or the like that has a thickness less than 150 μm such as 50 μm to 150 μm. It is appreciated that other thicknesses for die  110  are possible. 
         [0020]      FIG. 1  shows that portion  1200 A of carrier  120  includes multiple build-up layers including dielectric layers  130  of, for example, ABF and one or more electrically conductive layers or lines  140  (one shown) of, for example, copper or a copper alloy (connected with conductive vias or the like) that provide connectivity to die  110  (power, ground, input/output, etc.) through contacts  145  such as, for example, contacts suitable for a surface mount packaging implementation (e.g., a ball grid array). Die  110  and portion  1200 A of carrier  120  are in direct physical contact with each other (e.g., there are no solder bumps connecting die  110  to carrier  120 ). Die  110  is directly electronically connected to electrically conductive contacts or conductive vias of portion  1200 A of carrier  120 . As illustrated, at least one electrically conductive layer  140  is connected through electrically conductive vias to portion  1200 B. In  FIG. 1 , one of dielectric layers  130  surrounds the lateral side walls of die  110 . 
         [0021]    Underlying a back side of die  110  of microelectronic package  100  in  FIG. 1 , as viewed, is adhesive layer  150  of, for example, a die backside film (DBF) polymer, epoxy based adhesive with or without fillers. Underlying adhesive layer  150  is portion  1200 B of carrier  120 . Portion  1200 B includes additional build-up layers including dielectric layers  160  and one or more electrically conductive layers or lines  170 . Dielectric layers  160  (e.g., two or more) may be of a material similar to a material for dielectric layers  130  (e.g., ABF) or a different material. Conductive layers  170  (one shown) are, for example, a copper or copper alloy material. In this embodiment, conductive layers  170  are connected with electrically conductive vias or the like to one or more conductive layers  140  of portion  1200 A of carrier  120 . 
         [0022]    In the embodiment shown in  FIG. 1 , package  100  also includes two secondary dice, die  125 A and die  125 B embedded in portion  1200 B of carrier  120 . In one embodiment, secondary dice are dice having a desired electrical configuration that may or may not be electrically connected to die  110 . In the embodiment, shown in  FIG. 1 , secondary die  125 A and secondary die  125 B are electrically connected to die  100  through routing layers in carrier  120 . Examples of secondary dice include but are not limited to a digital logic device, such as a dynamic random access memory (DRAM) device, a static random access memory (SRAM) device, a flash memory device, a microprocessor device, a digital signal processor (DSP) device, a graphics processor device, a crypto processor device, and an application specific integrated circuit (ASIC) device. In this embodiment, die  125 A and die  125 B are positioned device side up (as viewed). Die  125 A and die  125 B each contain electrical contact points (contacts) on a device side which are connected through electrically conductive vias to conductive layer  170 . 
         [0023]      FIG. 1  also shows contact lands  180  in portion  1200 B or carrier  120  at the interface of first portion  1200 A and second portion  1200 B. Contact lands  180  are connected to electrically conductive layers of carrier  120 , e.g., conductive layers of portion  1200 A of carrier  120  through electrically conductive vias. Contact lands  180  in connection with electrically conductive layer  170 , in this embodiment, provide a redistribution layer and together with electrically conductive vias to electrically conductive layer  140  an electrical connection between die  110  and dice  125 A and  125 B. Contact lands  180  may also allow additional interconnect points for the package (e.g., power, ground, input/output) between contacts  145  and secondary die  125 A and/or secondary die  125 B. 
         [0024]      FIG. 1  shows primary die  110  in portion  1200 A of carrier  120  and secondary dice  125 A and  125 B in portion  1200 B. In another embodiment, such positions are reversed.  FIG. 1  also shows two secondary dice. In another embodiment, a microelectronic package includes one secondary die. In a further embodiment, a microelectronic package includes more than two secondary dice. In a still further embodiment, a microelectronic package includes more than one primary die. 
         [0025]      FIGS. 2-9  describe one embodiment for forming a microelectronic package, such as microelectronic package  100  ( FIG. 1 ). Referring to  FIG. 2 ,  FIG. 2  shows an exploded cross-sectional side view of a portion of sacrificial substrate  210  of, for example, a prepeg material including opposing layers of copper foils  215 A and  215 B that are separated from sacrificial substrate  310  by shorter copper foil layers  220 A and  220 B, respectively. Copper foils  215 A and  215 B tend to stick to the shorter foils based on vacuum. One technique of forming build-up packages is to form two separate packages on a sacrificial substrate, one on a top surface sacrificial substrate  210  and one on a bottom surface (as viewed) and at some point during the formation process, each are separated from the sacrificial substrate. In the following description, a formation process will only be described and illustrated for a microelectronic package on the top surface. It is appreciated that a similar formation process may be followed on the bottom surface simultaneously. 
         [0026]      FIG. 3  shows the structure of  FIG. 2  following the introduction of secondary die  225 A and secondary die  225 B which are similar to secondary die  125 A and secondary die  125 B in  FIG. 1 . Secondary die  125 A and secondary die  125 B are attached to copper foil  215 A device side up by, for example, adhesive  250  of, for example, DBF. In addition to secondary die  225 A and secondary die  225 B on copper foil  215 A, contacts may optionally be introduced on copper foil  215 A that might be used to electrical connect the ultimately formed package to an external device or devices suitable contacts include two layer contacts of a gold-nickel alloy and a copper or copper alloy formed by deposition (plating, sputtering). 
         [0027]    Following the attachment of secondary die  225 A and secondary die  225 B and optional contacts, dielectric layer  260  of, for example, an ABF material possibly including a filler is introduced. One method of introduction of an ABF material is as a film that is laid on the secondary dice, the optional contacts and copper foil  215 A. 
         [0028]      FIG. 4  shows the structure of  FIG. 3  following the patterning of vias through dielectric layer  260  to contacts  227  on secondary die  225 A and secondary die  225 B and the formation of conductive vias and conductive layer  270  or line on each of dielectric layer  260 . In one embodiment, die  225 A and die  225 B may include electrically conductive pillars  228  on contacts  227 . Such pillars  228  may be added at the die fabrication stage. With regard to patterning vias in a material such as ABF, such patterning may be done by, for example, a drilling process. Once the vias are formed, electrical conductor (e.g., copper metal) patterning may be done in order to fill the vias and pattern electrically conductive layer or line  270  on dielectric layer  260 , for example, using an electroless seed layer followed by a dry film resist (DFR) patterning and plating. The DFR may then be stripped followed by a flash etch to remove any unwanted electroless seed layer. It is appreciated that other methods are also suitable.  FIG. 4  shows vias  235  filled with conductive material and represented as conductive vias including conductive vias to contacts  227  of respective secondary die  225 A and secondary die  225 B. 
         [0029]      FIG. 5  shows the structure of  FIG. 4  following the introduction of a dielectric layer.  FIG. 5  shows dielectric layer  275  of, for example, an ABF material introduced as a film.  FIG. 5  also shows the patterning of electrically conductive vias  265  formed through dielectric layer  275  to electrically conductive layer  270 . A suitable material for electrically conductive vias  265  is copper deposited, for example, by an electroless process. 
         [0030]      FIG. 6  shows the structure of  FIG. 5  following the patterning of contact lands on conductive vias  265 . Contact lands  268  are, for example, a copper or copper alloy deposited, for example, using an electroless seed layer followed by a DFR patterning and plating. 
         [0031]      FIG. 7  shows the structure of  FIG. 6  following the mounting of die  340  on dielectric layer  275  (on a top surface of dielectric layer  275  as viewed). In this embodiment, die  340  is connected by adhesive  350 . A suitable adhesive material is DBF. In this embodiment, die  340  is positioned device side up (device side facing away from copper foil). Die  340  may include electrically conductive pillars  348  on contacts  347  (contact points). Such pillars  348  may be added at the die fabrication stage. In another embodiment, die  340  may have through substrate vias from a device side to a back side of the die. In such an embodiment, conductive vias  265  and optionally contact lands  268  could be patterned to conductive layer  270  in an area directly below die  340  to connect directly to the through substrate vias of die  340 . 
         [0032]      FIG. 8  shows the structure of  FIG. 7  following the introduction of a dielectric layer.  FIG. 8  shows dielectric layer  360  of, for example, an ABF material introduced as a film. Dielectric layer  360  encompasses or encapsulates die  340 . 
         [0033]      FIG. 9  shows the structure of  FIG. 8  following the formation of openings  365  to contact lands  268  and to contact points on a device side of die  340  (openings to pillars  348 ). One way to form openings  365  through a dielectric material such as ABF is by a drilling process. 
         [0034]      FIG. 10  shows the structure of  FIG. 9  following the introduction of an electrical conductor (e.g., copper metal) in openings  365  and patterning of the conductor material into electrically conductive layer or line  370 . One method includes using an electroless seed layer followed by a dry film resist (DFR) patterning and plating. The DFR may then be stripped followed by a flash etch to remove any unwanted electroless seed layer. It is appreciated that other methods are also suitable. 
         [0035]    Once electrically conductive layer  370  is introduced and patterned, a dielectric layer is introduced on the structure.  FIG. 10  shows the structure of  FIG. 9  following the introduction of dielectric layer  380  on the structure and encapsulating electrically conductive layer  370 . Patterning of additional levels of conductive lines (e.g., three additional levels separated from one another by dielectric layers (e.g., ABF film)) may follow. A typical BBUL package may have four to six levels of conductive lines or traces connected to one another or die  340  by conductive vias. 
         [0036]      FIG. 11  shows the structure of  FIG. 10  following the formation of openings through dielectric layer  380  to electrically conductive layer  370  and the introduction of an electrical conductor (e.g., copper metal) in the openings to form conductive vias  390  to which, for example, solder balls may be attached for a surface mount implementation.  FIG. 11  also shows the structure following the separation of the structure from sacrificial substrate  210  and copper foil  215 A. By removing the individual packages from sacrificial substrate  210  and copper foil  215 A,  FIG. 11  shows a free standing microelectronic package that has a primary die and secondary dice  225 A and  225 B therein. 
         [0037]      FIG. 12  illustrates a computing device  400  in accordance with one implementation. Computing device  400  houses board  402 . Board  402  may include a number of components, including but not limited to processor  404  and at least one communication chip  406 . Processor  404  is physically and electrically coupled to board  402 . In some implementations the at least one communication chip  406  is also physically and electrically coupled to board  402 . In further implementations, communication chip  406  is part of processor  404 . 
         [0038]    Depending on its applications, computing device  400  may include other components that may or may not be physically and electrically coupled to board  402 . These other components include, but are not limited to, volatile memory (e.g., DRAM), non-volatile memory (e.g., ROM), flash memory, a graphics processor, a digital signal processor, a crypto processor, a chipset, an antenna, a display, a touchscreen display, a touchscreen controller, a battery, an audio codec, a video codec, a power amplifier, a global positioning system (GPS) device, a compass, an accelerometer, a gyroscope, a speaker, a camera, and a mass storage device (such as hard disk drive, compact disk (CD), digital versatile disk (DVD), and so forth). 
         [0039]    Communication chip  406  enables wireless communications for the transfer of data to and from computing device  400 . The term “wireless” and its derivatives may be used to describe circuits, devices, systems, methods, techniques, communications channels, etc., that may communicate data through the use of modulated electromagnetic radiation through a non-solid medium. The term does not imply that the associated devices do not contain any wires, although in some embodiments they might not. Communication chip  406  may implement any of a number of wireless standards or protocols, including but not limited to Wi-Fi (IEEE 802.11 family), WiMAX (IEEE 802.16 family), IEEE 802.20, long term evolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM, GPRS, CDMA, TDMA, DECT, Bluetooth, derivatives thereof, as well as any other wireless protocols that are designated as 3G, 4G, 5G, and beyond. Computing device  400  may include a plurality of communication chips  406 . For instance, a first communication chip  406  may be dedicated to shorter range wireless communications such as Wi-Fi and Bluetooth and a second communication chip  406  may be dedicated to longer range wireless communications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, and others. 
         [0040]    Processor  404  of computing device  400  includes an integrated circuit die packaged within processor  404 . In some implementations, the package formed in accordance with embodiment described above utilizes BBUL technology with a carrier includes a primary die (e.g., microprocessor or SOC die) and one or more secondary dice (e.g., memory die or dice). The term “processor” may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into other electronic data that may be stored in registers and/or memory. 
         [0041]    Communication chip  406  also includes an integrated circuit die packaged within communication chip  406 . In accordance with another implementation, package is based on BBUL technology with a carrier includes a primary die (e.g., microprocessor or SOC die) and one or more secondary dice (e.g., memory die or dice). Such packaging will enable integration in a single package various devices, including but not limited to, a microprocessor chip (die) with a memory die with a graphics die with a chip set with GPS. 
         [0042]    In further implementations, another component housed within computing device  400  may contain a microelectronic package based on BBUL technology with a carrier includes a primary die (e.g., microprocessor or SOC die) and one or more secondary dice (e.g., memory die or dice). 
         [0043]    In various implementations, computing device  400  may be a laptop, a netbook, a notebook, an ultrabook, a smartphone, a tablet, a personal digital assistant (PDA), an ultra mobile PC, a mobile phone, a desktop computer, a server, a printer, a scanner, a monitor, a set-top box, an entertainment control unit, a digital camera, a portable music player, or a digital video recorder. In further implementations, computing device  400  may be any other electronic device that processes data. 
         [0044]    In the description above, for the purposes of explanation, numerous specific details have been set forth in order to provide a thorough understanding of the embodiments. It will be apparent however, to one skilled in the art, that one or more other embodiments may be practiced without some of these specific details. The particular embodiments described are not provided to limit the invention but to illustrate it. The scope of the invention is not to be determined by the specific examples provided above but only by the claims below. In other instances, well-known structures, devices, and operations have been shown in block diagram form or without detail in order to avoid obscuring the understanding of the description. Where considered appropriate, reference numerals or terminal portions of reference numerals have been repeated among the figures to indicate corresponding or analogous elements, which may optionally have similar characteristics. 
         [0045]    It should also be appreciated that reference throughout this specification to “one embodiment”, “an embodiment”, “one or more embodiments”, or “different embodiments”, for example, means that a particular feature may be included in the practice of the invention. Similarly, it should be appreciated that in the description various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects may lie in less than all features of a single disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of the invention.