PATENT DOCUMENT

Publication Number: US-9754924-B2
Application Number: US-201615164296-A
Country: US
Kind Code: B2

Title: Fan-out pop stacking process

Abstract:
Package on package structures and manners of formation are described. In an embodiment, an array of trenches is formed partially through a fan-out substrate. In an embodiment, a plurality of laterally separate locations thermal interface material is dispensed onto an array of embedded bottom die. In an embodiment a thermal compression tool including an array of cavities corresponding to an array of top packages is brought into contact with the array of top packages and underlying fan-out substrate during PoP joint formation. The fan-out substrate may be secured to a vacuum chuck during several processing operations.

Claims:
What is claimed is: 
     
       1. A method of forming a semiconductor device package comprising:
 forming an array of trenches partially through an active side of a fan-out substrate, wherein a second side of the fan-out substrate opposite the active side is supported by a carrier substrate during forming the array of trenches, and the fan-out substrate further comprises:
 a plurality of embedded bottom die on the carrier substrate and embedded within a polymer-based molding compound; and 
 a redistribution layer spanning over the polymer-based molding compound and the plurality of embedded bottom die, wherein the redistribution layer includes a plurality of conductive lines that fan-out electrical connections with the plurality of embedded bottom die; 
 
 removing the carrier substrate after forming the array of trenches partially through the active side of the fan-out substrate; and 
 placing an array of top packages onto the second side the fan-out substrate after removing the carrier substrate. 
 
     
     
       2. The method of  claim 1 , wherein the array of top packages are placed onto the second side of the fan-out substrate directly over the array of embedded bottom die. 
     
     
       3. The method of  claim 1 , wherein the trenches do not extend completely through the polymer-based molding compound. 
     
     
       4. The method of  claim 1 , further comprising prior to removing the carrier substrate from the fan-out substrate, mounting the active side of the fan-out substrate to a temporary adhesive layer. 
     
     
       5. The method of  claim 1 , wherein placing the array of top packages onto the fan-out substrate comprises bringing a thermal compression tool into contact with the array of top packages and the fan-out substrate to thermally join the array of top packages and the fan-out substrate, wherein the thermal compression tool includes a plurality of spacers structures that define an array of cavities that receive the array of top packages. 
     
     
       6. The method of  claim 5 , further comprising holding the fan-out substrate on a vacuum chuck while bringing the thermal compression tool into contact with the array of top packages and the fan-out substrate to thermally join the array of top packages and the fan-out substrate. 
     
     
       7. The method of  claim 1 , wherein the fan-out substrate further includes an array of through interconnects that extend through the polymer-based molding compound to provide electrical connections from the redistribution layer to the second side of the fan out substrate. 
     
     
       8. The method of  claim 7 , wherein placing an array of top packages onto the second side the fan-out substrate comprises connecting the array of top packages to the array of through interconnects with conductive bumps. 
     
     
       9. The method of  claim 8 , further comprising applying an underfill material to the array of top packages after placing an array of top packages onto the second side the fan-out substrate. 
     
     
       10. The method of  claim 8 , further comprising singulating multiple package structures, each package structure including an embedded bottom die and a plurality of the through interconnects. 
     
     
       11. The method of  claim 10 , wherein singulating the multiple package structures comprises cutting though the array of trenches. 
     
     
       12. The method of  claim 1 , wherein the redistribution layer comprises multiple layers of conductive lines. 
     
     
       13. The method of  claim 1 , wherein the polymer-based molding compound comprises epoxy. 
     
     
       14. The method of  claim 1 , wherein each embedded bottom die comprises a system on chip die. 
     
     
       15. The method of  claim 14 , wherein each top package comprises a memory package. 
     
     
       16. The method of  claim 1 , wherein each embedded bottom die comprises a memory die. 
     
     
       17. The method of  claim 16 , wherein each top package comprises a memory package.

Description:
RELATED APPLICATIONS 
     The present application is a continuation of co-pending U.S. patent application Ser. No. 14/494,253 filed Sep. 23, 2014, which claims the benefit of priority from U.S. Provisional Patent Application Ser. No. 62/030,029 filed on Jul. 28, 2014, both of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Field 
     Embodiments described herein relate to semiconductor packaging. More particularly embodiments relate to package on package (PoP) structures and manners of fabrication. 
     Background Information 
     Package on package (PoP) applications have become increasingly popular as the demand for higher component density continues in devices, such as mobile phones, personal digital assistants (PDAs) and digital cameras. In one implementation, PoP structures include multiple memory packages stacked onto on one another. In another implementation, PoP structures include mixed logic-memory package stacks, such as system on chip (SoC) packages with memory packages. In such an implementation, the bottom package is typically the SoC package since the logic requires more I/O terminals and the top package is a memory package. 
     SUMMARY 
     Package on package structures and manners of formation that may address warpage are described. In an embodiment, an array of trenches is formed partially through a fan-out substrate prior to bonding an array of top packages to the fan-out substrate. For example, the array of trenches may be formed in an active side of the fan-out substrate, followed by mounting the active side of the fan-out substrate to a temporary adhesive layer, and removal of a carrier substrate from the fan-out substrate. The array of top packages may then be bonded to a surface of the fan-out substrate opposite the active side of the fan-out substrate. In an embodiment, at a plurality of laterally separate locations thermal interface material is dispensed onto an array of embedded bottom die of a fan-out substrate prior to bonding an array of top packages to the fan-out substrate. In an embodiment a thermal compression tool including an array of cavities corresponding to an array of top packages is brought into contact with the array of top packages and underlying fan-out substrate during PoP joint formation. In an embodiment, the fan-out substrate is held on a vacuum chuck while thermally bonding the array of top packages and the fan-out substrate. The fan-out substrate may be secured to a vacuum chuck during several processing operations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional side view illustration of a fan-out substrate including multiple embedded bottom die in accordance with an embodiment. 
         FIG. 2  is a cross-sectional side view illustration of trenches formed partially through a fan-out substrate in accordance with an embodiment. 
         FIGS. 3A-3B  are schematic top view illustrations of arrangements of trenches formed partially through a fan-out substrate including embedded bottom die in accordance with embodiments. 
         FIG. 4  is a cross-sectional side view illustration of a fan-out substrate with a cut overmold bonded to a temporary adhesive layer in accordance with an embodiment. 
         FIG. 5  is a cross-sectional side view illustration of a thermal interface material formed over embedded bottom die of a fan-out substrate while the fan-out substrate is constrained by a vacuum chuck in accordance with an embodiment. 
         FIG. 6  is a cross-sectional side view illustration of a plurality of top packages placed onto embedded bottom die of a fan-out substrate in accordance with an embodiment. 
         FIG. 7  is a cross-sectional side view illustration of a thermal compression tool bonding the top packages to a fan-out substrate while the fan-out substrate is constrained by a vacuum chuck in accordance with an embodiment. 
         FIG. 8  is a close-up cross-sectional side view illustration of a portion of a thermal compression tool over a top package in accordance with an embodiment. 
         FIGS. 9A-9C  are schematic top view illustrations of arrangements of thermal compression tool spacers and top packages in accordance with embodiments. 
         FIG. 10  is a cross-sectional side view illustration of an underfill material applied to the top packages in accordance with an embodiment. 
         FIG. 11  is a cross-sectional side view illustration of a singulated fan-out package on package structure in accordance with an embodiment. 
         FIG. 12  is a cross-sectional side view illustration of a singulated fan-out package on package structure in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments describe package on package (PoP) structures and manners of fabrication. In various embodiments, description is made with reference to figures. However, certain embodiments may be practiced without one or more of these specific details, or in combination with other known methods and configurations. In the following description, numerous specific details are set forth, such as specific configurations, dimensions and processes, etc., in order to provide a thorough understanding of the present invention. In other instances, well-known semiconductor processes and manufacturing techniques have not been described in particular detail in order to not unnecessarily obscure the present invention. Reference throughout this specification to “one embodiment” means that a particular feature, structure, configuration, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrase “in one embodiment” in various places throughout this specification are not necessarily referring to the same embodiment of the invention. Furthermore, the particular features, structures, configurations, or characteristics may be combined in any suitable manner in one or more embodiments. 
     The terms “over”, “to”, “between” and “on” as used herein may refer to a relative position of one layer with respect to other layers. One layer “over” or “on” another layer or bonded “to” or in “contact” with another layer may be directly in contact with the other layer or may have one or more intervening layers. One layer “between” layers may be directly in contact with the layers or may have one or more intervening layers. 
     Embodiments describe PoP structures and manners of fabrication which may address warping and thermal performance issues found in conventional PoP structures and fabrication processes. It has been observed that as the thickness and pitch in PoP packages is reduced there is a greater potential for warping of either the top or bottom packages, particularly after PoP joint formation (reflow of the conductive bumps attaching the two package structures). Warping can additionally occur at the large-scale across a fan-out substrate where the bottom package of a PoP structure is formed using a fan-out wafer level packaging (FOWLP) or fan-out panel level packaging process. Thus, warping can be at the local PoP structure level and at the wafer or panel level across multiple PoP structures prior to singulation. Warping may lead to failure or reduced performance of the resultant PoP structure and/or problems in reliability of devices incorporating the PoP structure. 
     In one aspect, embodiments describe a fan-out PoP fabrication manner in which a thickness of a fan-out substrate is partially cut to address warpage. For example, trenches may be cut into an overmold in which embedded bottom die are embedded. The cuts may reduce residual stress in the fan-out substrate (including the embedded bottom die, shared overmold and redistribution layers) during the remaining process sequence of forming the fan-out PoP structures. 
     In one aspect, embodiments describe a fan-out PoP fabrication manner in which the fan-out substrate is flattened/constrained when held by a vacuum chuck (or other suitable chucking mechanism) during certain processing sequences of forming the PoP structure in order to address warpage. For example, the fan-out substrate may be flatted/constrained by vacuum chucking during dispensing of a thermal interface material (TIM) on the embedded bottom die, placement of the top packages on the embedded bottom die, and during PoP joint formation. 
     In one aspect, embodiments describe fan-out PoP structures and manners of fabrication in which a thermal interface material (TIM) is provided at the embedded bottom die area of the fan-out substrate and beneath a corresponding top package. In this manner, the TIM may improve thermal properties of the fan-out PoP structure and add mechanical protection to the top packages. In an embodiment, the TIM may aid in securing the top packages, reduce x-y shifting of the top packages prior to and during PoP joint formation, and control z-height prior to and during PoP joint formation. 
     In one aspect, embodiments describe a fan-out PoP fabrication manner in which a thermal compression tooling constrains the top packages during PoP joint formation. In this manner, constraining the top packages may address warpage of the top packages, x-y shifting of the top packages, and z-height control of the PoP gap between the top and bottom packages. In addition, in embodiments employing a TIM, constraining the top packages with the thermal compression tooling may aid in achieving a uniform TIM bond-line thickness (BLT), which may improve thermal performance as well as warping. 
     In an embodiment, a thermal compression tooling is sized to fit over all of the top packages and simultaneously bond the top packages to the fan-out substrate for PoP joint formation. In an embodiment, the thermal compression tooling includes a rim spacer that fits around the top packages, and an array of package spacers. The rim spacer and package spacers may be characterized by a same height. The array of package spacers may define an array of cavities into which an array of top packages fit for PoP joint formation. Additionally, an arrangement of vents may be formed through a top surface of the thermal compression tooling to allow for the escape of volatile components during PoP joint formation. 
     In the following description, fan-out PoP fabrication manners and structures are described and illustrated which include structural features and processing techniques that may aid in addressing warpage of the top and bottom packages in a fan-out PoP structure. It is to be appreciated, that while the structures and processing techniques are described and illustrated cumulatively, that embodiments are not so limited, and embodiments may incorporate some and not all of the structural features and processing techniques. 
     Referring now to  FIG. 1 , a fan-out substrate is illustrated in accordance with an embodiment. As shown, a fan-out substrate  100  is supported by a carrier substrate  102  such as a wafer (e.g. silicon), glass, metal, or polymer. In the following description carrier substrate  102  is illustrated as circular. In an embodiment, carrier substrate is a 300 mm wafer. Carrier substrate  102  may also be rectangular or square, for example, as related to fan-out panel level packaging applications. A size and shape of the carrier substrate and fan-out substrate can be varied depending upon application. An array of embedded bottom die  106  is on the carrier substrate  102  and embedded within an overmold  110 . Each embedded bottom die  106  may be, for example, a silicon chip, an integrated circuit die, or a flip chip die. In an embodiment, embedded bottom die  106  is a logic die. For example, embedded bottom die  106  may be a system on chip (SoC). Overmold  110  may be an encapsulant material such as a polymer or mold compound, for example, epoxy. Through interconnects  104  may extend through the overmold  110  to provide an electrical connection therethrough from an active side  115  of the fan-out substrate  100  to an opposite surface  114  of the fan-out substrate  100  on the carrier substrate  102 . In an embodiment through interconnects  104  are formed of copper. 
     A redistribution layer  120  may be formed over the overmold  110 , through interconnects  104 , and embedded bottom die  106 . The redistribution layer  120  includes one or more layers of conductive lines  122 , such as copper, and passivation layers  124  to fan-out electrical connections with the embedded bottom die  106  and through interconnects  104 . Openings  126  are formed in a top passivation layer  124  to accommodate conductive bumps  130 , such as solder balls. Openings  128  may additionally be patterned in the redistribution layer  120  on an active side  115  of the fan-out substrate at locations between or surrounding the embedded bottom die  106  and through interconnects  104  that will be included in each bottom package of the PoP structure to be formed. In this manner, the electrical fan-out will be separate for each bottom package. In an embodiment, openings  128  are not formed, and one or more top passivation layers  124  extend between each embedded bottom die  106 , while the conductive lines  122  are not formed in such regions, so that the electrical fan-out is separate for each bottom package. 
     Referring now to  FIG. 2 , trenches  140  are formed partially though the fan-out substrate  100  on the active side  115  using a suitable technique such as laser cutting or cutting with a mechanical saw. In this manner, the cut trenches  140  may release residual stress in the fan-out substrate, which can assist in flattening the fan-out substrate  100  and reducing warpage, for example when fan-out substrate  100  is heated. In an embodiment, the trenches  140  are cut to a distance d below a top surface of the fan-out substrate, where d is less than t, with t being a thickness of the fan-out substrate. In the particular embodiment illustrated, the trenches  140  are formed through existing openings  128  in the redistribution layer  120 . As shown, trenches  140  extend partially through the overmold  110  and do not reach the carrier substrate  102 . While the fan-out substrate  100  has been described and illustrated using particular structural features, embodiments are not limited to the particular fan-out substrate structure described and illustrated. For example, a variety of additional layers can be included, such as a bottom redistribution layer, or an alternative through interconnect structure, while trenches  140  may still be formed partially through a fan-out substrate including an array of embedded bottom die without extending completely through the fan-out substrate. 
       FIG. 3A  is a schematic top view illustration of an arrangement of trenches  140  formed partially through a fan-out substrate including embedded bottom die  106  in accordance with an embodiment. In the particular embodiment shown, trenches  140  extend at right angles between each embedded bottom die  106 , and surround each embedded bottom die  106 . In other embodiments alternative configurations are envisioned. In an embodiment, trenches  140  are arranged between multiple rows or columns of embedded bottom die  106 . In an embodiment, trenches  140  do not extend entirely across (laterally, or vertically) the entire arrangement of embedded bottom die  106 , and instead trenches  140  extend across sections of the arrangement of embedded bottom die and laterally between the embedded bottom die  106 . In an embodiment, trenches  140  are approximately 30 μm-100 μm wide. Trenches  140  may be formed along areas of largest stress in the fan-out substrate  100 . In an embodiment illustrated in  FIG. 3B , trenches  140  are formed around a periphery of fan-out substrate  100 . In the particular embodiment illustrated, trenches  140  are formed around a portion of the embedded bottom die  106  near edges of the fan-out substrate  100 , where stress may be higher. In this manner, there is a higher concentration or density of trenches  140  near a periphery of the fan-out substrate  100  than a center of the fan-out substrate. 
     Following the formation of trenches  140 , the active side  115  of the fan-out substrate  100  is mounted onto a temporary adhesive layer  150 , and the carrier substrate  102  is removed, exposing surface  114  of the fan-out substrate  100 , as illustrated in  FIG. 4 . As illustrated, the trenches  140  do not extend to surface  114 . In the particular embodiment illustrated, surface  114  exposes the overmold  110 , through interconnects  104 , and embedded bottom die  106 . As previously described above, fan-out substrate  100  may include additional layers, such as a redistribution layer at surface  114 . 
     Referring now to  FIG. 5 , in an embodiment a plurality of laterally separate locations of a thermal interface material (TIM)  154  are dispensed over the embedded bottom die  106 . In an embodiment, TIM  154  may then be at least partially cured or dried after PoP joint formation. In the embodiment illustrated, the fan-out substrate  100  is secured with a vacuum chuck  152  (or other suitable chucking mechanism) to flatten the fan-out substrate during application of TIM  154 . Suitable dispensing techniques include, but are not limited to, ink jet printing or screen printing. A variety of materials may be used as the TIM in accordance with embodiments. For example, the TIM may be an adhesive, thermal grease (e.g. a thermally conductive filler dispersed in a silicone or hydrocarbon oil to form a paste), or gel. In application, the TIM may be used as an underfill and may improve thermal performance of the completed PoP structure. In addition, a TIM may be easily deformed by small contact pressures with minimal leakage, or flow. In this manner, the TIM may be selectively located and not flow away from the area it was applied. In addition, the TIM may add mechanical protection to the top packages, secure the top packages to the fan-out substrate, reduce x-y shifting of the top packages, and provide z-height control. In an embodiment, the TIM is a silicone-based thermal grease. In an embodiment, rather than applying a TIM, a more traditional underfill material  155  is applied. Underfill material  155  may be an encapsulant material (e.g. a polymer or mold compound, for example, epoxy) or a non-conductive paste (e.g. elastomeric paste with thermally conductive particles). Such an embodiment is described in more detail with regard to  FIG. 12 . 
     Referring now to  FIG. 6 , in an embodiment top packages  160  are picked and placed onto the fan-out substrate directly over the embedded bottom die  106 . In an embodiment, the top packages  160  are separated by a pitch of 100-300 μm across the fan-out substrate, though these pitches are exemplary, and can be varied depending upon application. Likewise, a size and shape of the fan-out substrate can be varied depending upon application. Flux or conductive paste can be applied to conductive bumps  162  using a suitable technique such as dipping, dispensing or jetting. In an embodiment, conductive bumps  162  (e.g. solder balls, printed conductor, or plated conductor) can be pre-formed on the top packages  160 . In an embodiment, conductive bumps  162  are formed on the fan-out substrate prior to picking and placing the top packages  160 . As illustrated in  FIG. 6 , conductive bumps  162  electrically connect the top packages  160  with the through interconnects  104  and redistribution layer  120 . 
     The TIM  154  may add mechanical protection to the top package  160 . For example, the TIM  154  can aid in securing and controlling z-height of the top package  160  at this stage, and additionally aid against x-y shift in the top packages  160  prior to being permanently joined. In the embodiment illustrated in  FIG. 6 , the conductive bumps  162  of a top package  160  laterally surround a corresponding laterally separate location of conductive paste  154  underneath the top package  160 . In an embodiment, the TIM  154  does not contaminate the conductive bumps  162  or spill out from underneath the top package  160  at this stage, or during subsequent PoP joint formation. 
     PoP joint formation may then be accomplished by bringing a thermal compression tool  170  into contact with the array of top packages  160  and the fan-out substrate to thermally join the array of top packages  160  and the fan-out substrate, as illustrated in  FIG. 7 . In an embodiment, the thermal compression tool  170  includes a base  178 , a rim spacer  172  extending from the base  178 , and an array of package spacers  174  extending from the base  178 , in which the array of package spacers define an array of cavities  175 . The rim spacer  172  may laterally surround the package spacers  174  and the top packages  160  on the fan-out substrate. As illustrated, the array of cavities  175  receives the array of top packages  160 . In an embodiment, the array of cavities  175  receives all of the top packages  160  that have been placed onto the fan-out substrate. 
       FIG. 8  is a close-up cross-sectional side view illustration of a portion of a thermal compression tool over a top package in accordance with an embodiment. In the particular embodiments illustrated, the rim spacers  172  and package spacers  174  have the same height extending from the base  178 , and make contact with the surface  114  of the fan-out substrate. In an embodiment, each cavity  175  receives a single top package  160 . In an embodiment, spacers  172 ,  174  have a height of approximately 350 μm-400 μm, though the height is exemplary and may vary depending upon application. The amount of open space in cavities  175  between sidewalls of the package spacers  174  and top packages  160  may be designed to define a maximum tolerance of x-y shift of the top packages  160 , and accommodate a vent hole  176  extending entirely through the base  178  to allow volatiles to escape during joint formation with the conductive bumps  162 , particularly where a flux is used. In an embodiment, there is approximately 40 μm-100 μm of space around the top packages  160  within each cavity  175 . The upper surface of the cavity  175  corresponding to the base  178  along with height of the spacers  172 ,  174  may control z-height of the PoP gap between the top and bottom packages during PoP joint formation. In an embodiment, at least one vent hole is located in each cavity  175 . 
     In an embodiment, the fan-out substrate is held by a vacuum chuck  152  during PoP joint formation, while thermal compression tool  170  contacts the array of top packages  160  and the fan-out substrate to thermally joint the array of top packages to the fan-out substrate. In this manner, the vacuum chuck can address warpage of the fan-out substrate while the thermal compression tool  170 , and optionally the TIM  154  address warpage of the top packages  160 . In this manner, mechanisms are in place during thermal compression to simultaneously address warpage of the resultant top and bottom packages of the PoP structure, and across substrate level (such as wafer-level or panel-level). In the particular embodiment illustrated incorporating a TIM  154 , use of the thermal compression tool  170  may aid in achieving a uniform TIM  154  bond-line thickness (BLT), which may improve thermal performance as well as warping. 
     Referring now to  FIGS. 9A-9C , different schematic top view illustrations are provided to illustrate exemplary arrangements of the rim spacer  172  and package spacers  174 . In the embodiment illustrated in  FIG. 9A , the package spacers  174  are arranged in a grid configuration of rows and columns extending between opposite sides of the rim spacer  172 . In the embodiment illustrated in  FIG. 9B , the package spacers  174  are arranged in a rectangular corner configuration. For example, the package spacers  174  may have an X-shape, though others are contemplated. In the embodiment illustrated in  FIG. 9C , a rim spacer  172  is present, with no package spacers. In an embodiment the thermal compression tool of  FIG. 9C  is used in combination with a TIM  154 , in which the TIM aids in securing x-y shift of the top packages  160 , while rim spacer controls z-height during PoP joint formation. In the embodiments illustrated in  FIGS. 9A-9C , rim spacer  172  has been illustrated as circular. Rim spacer  172  may also be rectangular or square, depending upon application. 
     Following PoP joint formation, in an embodiment an underfill material  180  is applied to the array of top packages, as illustrated in  FIG. 10 . Underfill material  180  may be an encapsulant material such as a polymer or mold compound, for example, epoxy. As illustrated, the underfill material  180  is applied between packages  160  and flows underneath packages  160  to surround the PoP joints (e.g. conductive bumps  162  that join the top package  160  to the bottom package) and is then cured. In this manner, the underfill material  180  can provide mechanical and chemical protection to the PoP joints. As illustrated, the underfill material  180  additionally surrounds the TIM  154  underneath each top package  160 . In an embodiment, the underfill material  180  is characterized by a lower thermal conductivity than the TIM  154 . For example, the TIM  154  may have a thermal conductivity k value of approximately 3-10 W per meter per Kelvin (W·m −1 ·K −1 ), for example, when formed of a silicone-based material, while an epoxy containing underfill material  180  may have a thermal conductivity k value of approximately 0.5-3 W per meter per Kelvin (W·m −1 ·K −1 ). Both the TIM  154  and underfill material  180  may have approximately the same thickness between the top package  160  and the fan-out substrate, or bottom package to be formed as illustrated in  FIGS. 11-12 . 
     Following the application and curing of the underfill material  180 , an array of PoP structures  200  is singulated from the fan-out substrate and array of top packages  160 , with each separate PoP structure including a bottom package  202  (including an embedded bottom die  106 ) and a top package  160  on the bottom package. For example, singulation may be performed using a wafer saw. In an embodiment, the wafer saw has a cut width of approximately 60 um-300 μm. In an embodiment, the wafer saw cuts above the existing trenches  140  and removes any artifact of trenches  140 . In an embodiment, the remaining redistribution layer  120  is not as wide as the overmold  110  layer as a result of the openings  128  being wider than the cuts formed during singulation. In an embodiment, openings  128  are also removed as a result of singulating. 
       FIG. 11  is a cross-sectional side view illustration of a singulated fan-out PoP structure in accordance with an embodiment. As illustrated, the PoP structure  200  includes a thermal interface material  154  and cured underfill material  180  as described above. The remaining redistribution layer  120  is not as wide as the overmold  110  layer as a result of the openings  128  being wider than the cuts formed during singulation. Alternatively, they may have the same width. As illustrated, the underfill material  180  additionally spreads along lateral sidewalls of the top package  160 . 
       FIG. 12  is a cross-sectional side view illustration of a singulated fan-out PoP structure in accordance with an embodiment. As described above with regard to  FIG. 5 , in an embodiment, rather than dispensing a TIM  154 , laterally separate locations of underfill material  155  are dispensed over the array of embedded bottom die  106 . Underfill material  155  may be an encapsulant material (e.g. a polymer or mold compound, for example, epoxy) or a non-conductive paste (e.g. elastomeric paste with thermally conductive particles). In such an embodiment, the underfill material  155  spreads out and surrounds the conductive bumps  162  used to form the PoP joints. Accordingly, in such an embodiment, the underfill material  155  is pre-applied prior to PoP joint formation, for example with thermal compression tool  170 . 
     In utilizing the various aspects of the embodiments, it would become apparent to one skilled in the art that combinations or variations of the above embodiments are possible for forming a PoP structure. Although the embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that the appended claims are not necessarily limited to the specific features or acts described. The specific features and acts disclosed are instead to be understood as embodiments of the claims useful for illustration.

Metadata:
Filing Date: 20160525
Publication Date: 20170905
Grant Date: 20170905
Priority Date: 20140728
Inventors: CHUNG CHIH-MING
Assignee: APPLE INC
CPC Classifications: [{"code": "H01L25/50", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01L23/49838", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L24/81", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L2924/1431", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/12105", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/73151", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2225/1082", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2225/1088", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2221/68327", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2225/06548", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/81203", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2924/10253", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/49173", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/32225", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2225/1058", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/41171", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/16146", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/751", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L23/562", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L24/96", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L24/73", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L24/97", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L21/563", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/04105", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2225/06589", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/73267", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L24/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L2924/14", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/40108", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/48108", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/7555", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2225/1035", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L24/75", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L25/0657", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01L2924/15311", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L21/561", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/49171", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/26", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L23/5389", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L25/50", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L23/49811", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L2224/75981", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2225/06568", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L21/6835", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L24/92", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L2924/15172", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2225/06513", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2924/3511", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/753", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L24/19", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L2225/1094", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/8136", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/18", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L25/105", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L21/78", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L2924/15172", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2924/1431", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2924/14", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2225/1094", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2225/1088", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2225/1082", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2225/1035", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/73151", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/49173", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/49171", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/48108", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/41171", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/40108", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2221/68327", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L24/92", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L24/73", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L24/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L23/562", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L23/5389", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L21/6835", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L21/563", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2924/15311", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2924/10253", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/73267", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/32225", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L21/561", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2225/1058", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L25/105", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L23/49811", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L2224/04105", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L24/97", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L24/19", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L2924/15311", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2924/1431", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2924/14", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2924/10253", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2225/1094", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2225/1088", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2225/1082", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2225/1035", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/73267", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2224/73151", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2221/68327", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L24/92", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L24/73", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L24/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L23/562", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L23/5389", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L21/6835", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L23/49811", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L2224/32225", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2225/1058", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L25/105", "inventive": true, "first": false, "tree": "[]"}, {"c
Family ID: 55167334