Thin stacked interposer package

[0001] Not Applicable

[0002] Not Applicable

[0003] 1. Field of the Invention

[0004] The present invention relates generally to integrated circuit chip package technology and, more particularly, to a semiconductor package which is configured in a manner wherein two complimentary laminate substrate elements (i.e., a bottom element and a top element) are electrically connected to each other subsequent to one or both of the substrate elements being populated with various electronic components. Further in accordance with the present invention, there is provided a stacked wafer level chip scale package (WLCSP).

[0005] 2. Description of the Related Art

[0006] Semiconductor dies are conventionally enclosed in plastic packages that provide protection from hostile environments and enable electrical interconnection between the semiconductor die and an underlying substrate such as a printed circuit board (PCB) or motherboard. The elements of such a package include a metal leadframe, an integrated circuit or semiconductor die, bonding material to attach the semiconductor die to the leadframe, bond wires which electrically connect pads on the semiconductor die to individual leads of the leadframe, and a hard plastic encapsulant material which covers the other components and forms the exterior of the semiconductor package commonly referred to as the package body.

[0007] The leadframe is the central supporting structure of such a package, and is typically fabricated by chemically etching or mechanically stamping a metal strip. A portion of the leadframe is internal to the package, i.e., completely surrounded by the plastic encapsulant or package body. Portions of the leads of the leadframe extend externally from the package body or are partially exposed therein for use in electrically connecting the package to another component. In certain semiconductor packages, a portion of the die attach pad or die pad of the leadframe also remains exposed within the package body. In other semiconductor packages, the metal leadframe is substituted with a laminate substrate to which the semiconductor die is mounted and which includes pads or terminals for mimicking the functionality of the leads and establishing electrical communication with another device.

[0008] Once the semiconductor dies have been produced and encapsulated in the semiconductor packages described above, they may be used in a wide variety of electronic devices. The variety of electronic devices utilizing semiconductor packages has grown dramatically in recent years. These devices include cellular phones, portable computers, etc. Each of these devices typically includes a printed circuit board on which a significant number of such semiconductor packages are secured to provide multiple electronic functions. These electronic devices are typically manufactured in reduced sizes and at reduced costs, which results in increased consumer demand. Accordingly, not only are semiconductor dies highly integrated, but also semiconductor packages are highly miniaturized with an increased level of package mounting density.

[0009] Even though semiconductor packages have been miniaturized, space on a printed circuit board remains limited and precious. Thus, there is a need to find a semiconductor package design to maximize the number of semiconductor packages that may be integrated into an electronic device, yet minimize the space needed to accommodate these semiconductor packages. One method to minimize space needed to accommodate the semiconductor packages is to stack the semiconductor packages on top of each other, or to stack individual semiconductor devices or other devices within the package body of the semiconductor package. However, existing solutions for package stacking such as straddle mount laminate BGA or stacked die TSOP often do not meet form factor requirements. Therefore, a new solution is needed. The present invention is an extension of the stacking solution for space efficiency in that it is directed to, among other things, a semiconductor package which is configured in a manner wherein two complimentary laminate substrate elements (i.e., a bottom element and a top element) are electrically connected to each other subsequent to one or both of the substrate elements being populated with various electronic components. In this regard, the present invention provides a two-sided package architecture which allows topside routing (also known as a “lands-over-top” feature) while also enabling the embedding of multiple components, including but not limited to active, passive and prepackaged components. These, as well as other features and attributes of the present invention will be discussed in more detail below brief summary

[0010] In accordance with one embodiment of the present invention, there is provided a semiconductor package comprising a bottom semiconductor package substrate which is populated with one or more electronic components. The electronic component(s) of the bottom substrate are covered or encapsulated with a suitable mold compound which hardens into a package body of the semiconductor package. The package body is provided with one or more vias through the completion of lasering or similar drilling process, such via(s) providing access to one or more corresponding conductive contacts of the bottom substrate. These vias are either lined or at least partially filled with a conductive metal material. Subsequently, a top semiconductor package substrate (an interposer) which may optionally be populated with one or more electronic components is mounted to the package body and electrically connected to the conductive metal material within the via(s) of the package body.

[0011] In accordance with another embodiment of the present invention, there is provided a semiconductor package comprising a primary semiconductor die and a secondary semiconductor die which is electrically connected to the primary semiconductor die. The secondary semiconductor die is covered or encapsulated with a suitable mold compound which hardens into a package body of the semiconductor package. The package body is provided with one or more vias through the completion of a lasering or similar drilling process, such via(s) providing access to one or more corresponding conductive pads or terminals of the primary semiconductor die other than those to which the secondary semiconductor die is electrically connected. These vias are filled with a conductive metal material.

[0012] The present invention is best understood by reference to the following detailed description when read in conjunction with the accompanying drawings.

[0030] Common reference numerals are used throughout the drawings and detailed description to indicate like elements.

[0031] Referring now to the drawings wherein the showings are for purposes of illustrating various embodiments of the present invention only, and not for purposes of limiting the same, FIG. 1 depicts a semiconductor package 10 constructed in accordance with a first embodiment of the present invention. The semiconductor package 10 comprises a bottom substrate assembly 11, which itself comprises a laminate bottom substrate 12 which has a generally quadrangular configuration defining four (4) peripheral edge segments. In addition, the bottom substrate 12 defines a generally planar top surface 14 and an opposed, generally planar bottom surface 16. Disposed on the top surface 14 is a plurality of top contacts 18 of the bottom substrate 12. In the bottom substrate 12, the top contacts 18 are typically disposed in relative close proximity to the peripheral edge segments defined by the bottom substrate 12. Formed on the bottom surface 16 of the bottom substrate 12 is a plurality of bottom contacts 20. Though not shown in FIG. 1, the top and bottom contacts 18, 20 are electrically connected to each other in a prescribed pattern or arrangement by conductive vias which extend through the bottom substrate 12.

[0032] Attached to a central area of the top surface 14 of the bottom substrate 12 is at least one electronic component of the semiconductor package 10, and more particularly a die stack 22. The die stack 22 comprises a plurality of individual semiconductor dies 24 which are arranged in a stacked configuration. In this regard, the uppermost semiconductor die 24 in the die stack 22 is secured to the semiconductor die 24 below it by a layer 26 of suitable adhesive. Similarly, the attachment of the lowermost semiconductor die 24 in the die stack 22 to the top surface 14 of the bottom substrate 12 is facilitated by an adhesive layer 26. As shown in FIG. 1, two (2) semiconductor dies 24 are depicted as being included in the die stack 22. However, those of ordinary skill in the art will recognize that the die stack 22 may be assembled to include greater than the two semiconductor dies 24 depicted in FIG. 1, or may be substituted with a single semiconductor die 24 as shown in the embodiment of FIG. 4 which will be discussed in more detail below. In the semiconductor package 10, the pads or terminals of each of the semiconductor dies 24 of the die stack 22 are electrically connected to at least some of the top contacts 18 through the use of conductive wires 28. More particularly, in the semiconductor package 10, it is contemplated that the conductive wires 28 may extend from the semiconductor dies 24 to conductive pads, traces or the like which are disposed on the top surface 14 and in turn electrically connected to the top contacts 18 in a prescribed pattern or arrangement. It is further contemplated that the conductive wires 28 can be attached directly to the top contacts 18 in a prescribed pattern or arrangement. The conductive wires 28 may be fabricated from aluminum, copper, gold, silver or a functional equivalent. Though not shown in FIG. 1, it is contemplated that the lowermost semiconductor die 24 in the die stack 22 may be electrically connected to such conductive traces on the top surface 14 of the underlying bottom substrate 12 through the use of a flip-chip type connection as an alternative to the use of the wires 28 as shown in the embodiments in FIGS. 6-9 which will also be discussed in more detail below.

[0033] In the semiconductor package 10, the die stack 22, wires 28 and portions of the top surface 14 of the bottom substrate 12 are encapsulated or covered by an encapsulant material which, upon hardening, forms a package body 30 of the semiconductor package 10. The fully formed package body 30 directly contacts the top surface 14 of the bottom substrate 12, and extends in a substantially flush relationship to the peripheral edge segments thereof. In addition, the package body 30 defines multiple, generally planar side surfaces 32, and a generally planar top surface 34. Formed within the package body 30 subsequent to the fabrication thereof is a plurality of vias 36, each of which has a generally frusto-conical configuration. Each of the vias 36 extends from the top surface 34 of the package body 30 to a respective one of the top contacts 18 disposed on the top surface 14 of the bottom substrate 12. Thus, the number of vias 36 formed in the package body 30 preferably conforms to the number of top contacts 18 disposed on the top surface 14 of the bottom substrate 12. In the semiconductor package 10, each of the vias 36 is partially filled with a conductive metal material such as solder 38. Solder 38 is preferably filled into each of the vias 36 to a depth wherein the solder 38 within each via 36 terminates just below the top surface 34 of the package body 30. However, it is also contemplated that the solder 38 could extend to just above the top surface 34 of the package body 30 if the bottom substrate assembly 11 is used in conjunction with a land grid array (LGA) in lieu of the top substrate 40 which is described below. As will be recognized by those of ordinary skill in the art, the solder 38 filled into each via 36 is in direct, conductive communication with the top contact 18 disposed at the bottom of such via 36.

[0034] The semiconductor package 10 of the first embodiment further comprises a laminate top substrate 40 which is mechanically and electrically connected to the bottom substrate assembly 11 in a manner which will be described in more detail below. The top substrate 40 also has a generally quadrangular configuration defining four (4) peripheral edge segments. In addition, the top substrate 40 defines a generally planar top surface 42 and an opposed, generally planar bottom surface 44. Disposed in the approximate center of the top surface 42 of the top substrate 40 is a plurality of top contacts 46 of the top substrate 40. Those of ordinary skill in the art will recognize that the top contacts 46 may be provided anywhere on the top surface 42, the depicted placement in the central region thereof constituting one exemplary placement. Additionally, formed on the bottom surface 44 of the top substrate 40 is a plurality of bottom contacts 48 thereof. In the top substrate 40, the bottom contacts 48 are typically disposed in relative close proximity to the peripheral edge segments defined by the top substrate 40. Though not shown, the top and bottom contacts 46, 48 are electrically connected to each other by conductive vias which extend through the top substrate 40. Those of ordinary skill in the art will recognize that each top contact 46 may be electrically connected to one or more bottom contacts 48 in any pattern or arrangement through the use of such conductive vias. Formed on each bottom contact 48 of the top substrate 40 is a solder ball 50 which is used to facilitate the electrical connection of the top substrate 40 to the bottom substrate assembly as will be described below. Though the top substrate 40 is shown as being approximately the same size as the bottom substrate assembly 11, those of ordinary skill in the art will recognize that the top substrate 40 can also be larger or smaller than the bottom substrate assembly 11. Additionally, as indicated above, the top substrate 40 could be substituted with an LGA substrate, or could include a stud bump made from aluminum or copper wire.

[0035] In the semiconductor package 10, each solder ball 50 attached to a respective bottom contact 48 of the top substrate 40 is advanced into a respective one of the vias 36 formed in the package body 30 of the bottom substrate assembly 11. As will be recognized by those of ordinary skill in the art, such advancement is limited by the abutment of each solder ball 50 against the solder 38 filled into the corresponding via 36. When such abutment occurs, a slight gap will typically be defined between the top surface 34 of the package body 30 and the bottom surface 44 of the top substrate 40. The subsequent completion of a solder reflow process effectively mechanically and electrically connects the solder balls 50 of the top substrate 40 to the solder 38 in respective ones of the vias 36, thereby electrically connecting the bottom contacts 48 of the top substrate 40 to respective ones of the top contacts 18 of the bottom substrate 12. The reflow of the solder balls 50 and solder 38 will typically cause the bottom surface 44 of the top substrate 40 to either contact or be disposed in extremely close proximity to the top surface 34 of the package body 30. As further seen in FIG. 1, it is contemplated that an adhesive layer 52 may be interposed between the top surface 34 of the package body 30 and the bottom surface 44 of the top substrate 40 to strengthen the mechanical interconnection therebetween.

[0036] In the semiconductor package 10, the bottom substrate assembly 11 and the top substrate 40 are preferably sized and configured relative to each other such that when the top substrate 40 is electrically and mechanically connected to the bottom substrate assembly 11 in the above-described manner, the peripheral edge segments of the top substrate 40 extend in generally co-planar relation to respective ones of the peripheral edge segments of the bottom substrate 12. Similarly, the peripheral edge segments of the bottom and top substrates 12, 40 extend in generally flush, co-planar relation to respective ones of the side surfaces 32 of the package body 30. Further, when the top substrate 40 is electrically and mechanically connected to the bottom substrate assembly 11, the die stack 22 as well as the conductive wires 28 are also effectively positioned between the bottom and top substrates 12, 40, and more particularly the top surface 14 of the bottom substrate 12 and the bottom surface 44 of the top substrate 40. In the semiconductor package 10, the top contacts 46 of the top substrate 40 provide top side routing also know as a “lands-over-top” feature. Additionally, it is contemplated that each of the bottom contacts 20 of the bottom substrate 12 will include a solder ball 54 formed thereon to facilitate the electrical and mechanical connection of the semiconductor package 10 to an underlying substrate such as a printed circuit board. Additionally, it is contemplated that the bottom substrate 12 could be substituted with a land grid array (LGA) substrate.

[0037] FIGS. 2A-2C illustrate an exemplary sequence of steps which may be utilized to facilitate the fabrication of the bottom substrate assembly 11 of the semiconductor package 10. In the initial step of the fabrication process shown in FIG. 2A, the die stack 22 is mounted and electrically connected to the bottom substrate 12 in the above-described manner, with the package body 30 thereafter being formed over the die stack 22, wires 28 and top surface 14 of the bottom substrate 12. A laser drilling process is then completed in the manner shown in FIG. 2B to facilitate the formation of the vias 36 in the package body 30 in the above-described manner. In this regard, as previously explained, the vias 36 are oriented so as to extend form the top surface 34 of the package body 30 to respective ones of the top contacts 18 of the bottom substrate 12. Subsequent to the formation of the vias 36, each such via 36 is partially filled with the solder 38 as shown in FIG. 2C and in the manner also described above. The partial filling of the vias 36 with the solder 38 completes the fabrication of the bottom substrate assembly 11. As an alternative to the use of the above-described lasering process to facilitate the formation of the vias 36, it is contemplated that such vias 36 may be created by forming the package body 30 through the use of a special mold tool. More particularly, such mold tool is outfitted with a plurality of pins which engage respective ones of the top contacts 18 and are sized and oriented to define respective ones of the vias 36. Alternatively, the pins of the mold tool may be sized and configured so as not to engage the top contacts 18 and thus only partially define the vias 36. In this case, a lasering process is subsequently conducted to remove portions of the package body 30 as needed to complete the extension of each of the partially formed vias 36 to respective ones of the top contacts 18.

[0038] FIGS. 3A-3D illustrate an exemplary sequence of steps which may be used to facilitate the complete fabrication of the semiconductor package 10 shown in FIG. 1. In the initial step of the fabrication process shown in FIG. 3A, the bottom substrate assembly 11 is provided, such bottom substrate assembly 11 being fabricated in the manner described in FIGS. 2A-2C above. As shown in FIG. 3B, the adhesive layer 52 (e.g. an epoxy) is then dispensed upon a central portion of the top surface 34 of the package body 30 of the bottom substrate assembly 11. Thereafter, as shown in FIG. 3C, the solder balls 50 formed on the bottom contacts 48 of the top substrate 40 are advanced into respective ones of the vias 36 in the above-described manner so as to abut the solder 38 in such vias. As indicated above, the abutment of the solder balls 50 against the solder 38 in respective ones of the vias 36 typically results in a gap or space being defined between the bottom surface 44 of the top substrate 40 and the top surface 34 of the package body 30. As shown in FIG. 3D, the subsequent completion of a solder reflow process effectively mechanically and electrically connects the solder balls 50 to the solder 38 in respective ones of the vias 36, thus placing each of the bottom contacts 48 of the top substrate 40 into electrical communication with respective ones of the top contacts 18 of the bottom substrate assembly 11. Though, for purposes of clarity, FIGS. 1 and 3D depict the solder balls 50 and solder 38 as separate elements, those of ordinary skill in the art will recognize that the completion of the aforementioned reflow process effectively combines the solder balls 50 and solder 38 into a continuous column. The same holds true for the depictions in FIGS. 4 and 5 described below.

[0039] Referring now to FIG. 4, there shown a semiconductor package 10a constructed in accordance with a second embodiment of the present invention. The semiconductor package 10a is substantially similar in construction to the semiconductor package 10 described above, with the sole distinction between the semiconductor packages 10, 10a lying in the semiconductor package 10a including only a single semiconductor die 24a mounted and electrically connected to the bottom substrate 12a of the bottom substrate assembly 11a. The inclusion of the single semiconductor die 24a in the semiconductor package 10a is in contrast to the die stack 22 having the stacked semiconductor dies 24 which is included in the semiconductor package 10.

[0040] Referring now to FIGS. 5 and 6, there shown a semiconductor package 10b constructed in accordance with a third embodiment of the present invention. The semiconductor package 10b is substantially similar to the semiconductor package 10a shown in FIG. 4, except that the single semiconductor die 24b of the semiconductor package 10b is electrically connected to the bottom substrate 12b through the use of a flip-chip type connection, as opposed to the use of the conductive wires 28a used in conjunction with the semiconductor die 24a in the semiconductor package 10a. More particularly, in the semiconductor package 10b, conductive posts 56b which may be made of copper or a similar, suitable conductive material are used to electrically connect pads or terminals of the semiconductor die 24b to corresponding pads or traces of the bottom substrate 12b which are in turn electrically connected to the top contacts 18b thereof in a prescribed pattern or arrangement. Those of ordinary skill in the art will recognize that solder balls may also be used as an alternative to the conductive posts 56b. In FIG. 6, the solder 38b filled into each of the vias 36b in the package body 30b of the bottom substrate assembly 11b is clearly depicted, as is the direct engagement between the solder 38b in each via 36b and a respective one of the top contacts 18b included on the top surface 14b of the substrate 12b. Though not shown in FIGS. 5 and 6, it is contemplated that the top surface of the semiconductor die 24b could be exposed in the top surface 34b of the package body 30b rather than being covered by the package body 30b to reduce the overall thickness of the bottom substrate assembly 11b.

[0041] Referring now to FIG. 7, there shown a semiconductor package 10c constructed in accordance with a fourth embodiment of the present invention. The semiconductor package 10c is similar to the semiconductor package 10b described above in relation to FIGS. 5 and 6, with one distinction between the semiconductor packages 10b, 10c lying in the substitution of the conductive posts 56b of the semiconductor package 10b with the solder balls 58c included in the semiconductor package 10c. In this regard, the solder balls 58c are used to facilitate the electrical connection of the sole semiconductor die 24c included in the semiconductor package 10c to the bottom substrate 12c thereof. More particularly, in the semiconductor package 10c, the solder balls 58c are used to electrically connect pads or terminals of the semiconductor die 24b to corresponding pads or traces of the bottom substrate 12c which are in turn electrically connected to the top contacts 18c thereof in a prescribed pattern or arrangement.

[0042] A further distinction between the semiconductor packages 10b, 10c lies in the formation of solder balls 60c upon each of the top contacts 18c disposed on the top surface 14c of the substrate 12c. As is seen in FIG. 7, due to the formation of the solder balls 60c upon respective ones of the top contacts 18c, the vias 36c formed in the package body 30c of the bottom substrate assembly 11c extend to respective ones of such solder balls 60c, as opposed to extending to respective ones of the top contacts 18c. Along these lines, in contrast to the semiconductor package 10b wherein solder 38b is partially filled into each of the vias 36b, no solder is filled into each of the vias 36c in the semiconductor package 10c. In this regard, subsequent to the advancement of the solder balls 50c of the top substrate 40c into respective ones of the vias 36c, the completion of a solder reflow process effectively fuses the solder balls 50c to respective ones of the solder balls 60c as effectively places the bottom contacts 48c of the top substrate 40c into electrical communication with respective ones of the top contacts 18c of the bottom substrate 12c. As is further shown in FIG. 7, when the solder balls 58c are used to facilitate the electrical connection of the semiconductor die 24c to the bottom substrate 12c, an underfill material 62c is typically included in the bottom substrate assembly 11c, such underfill material 62c flowing about the solder balls 58c between the semiconductor die 24c and the top surface 14c of the bottom substrate 12c.

[0043] Referring now to FIG. 8, there shown a semiconductor package 10d which is constructed in accordance with a fifth embodiment of the present invention. The semiconductor package 10d is substantially similar to the semiconductor package 10c described above in relation to FIG. 7, with the sole distinction lying in the substitution of the solder balls 60c of the semiconductor package 10c with conductive posts 64d in the semiconductor package 10d. In this regard, in the semiconductor package 10d, the conductive posts 64d are formed on respective ones of the top contacts 18d disposed on the top surface 14d of the substrate 12d. Additionally, the vias 36d formed in the package body 30d extend from the top surface 34d to respective ones of the conductive posts 64d. The conductive posts 64d of the semiconductor package 10d are each preferably fabricated from a conductive metal material, such as copper. The conductive posts 64d may be soldered to respective ones of the top contacts 18d.

[0044] Referring now to FIG. 9, there shown a semiconductor package 10e which is constructed in accordance with a sixth embodiment of the present invention. The semiconductor package 10e is similar to the above-described semiconductor packages 10c, 10d shown in FIGS. 7 and 8, respectively, with the primary distinction lying in the elimination of the above-described solder balls 60c and conductive posts 64d in the semiconductor package 10e. More particularly, in the semiconductor package 10e, the vias 36e extend all the way to respective ones of the top contacts 18e disposed on the top surface 14e of the substrate 12e. However, rather than each of the vias 36e being partially filled with solder similar to the partial filling of the vias 36b with solder 38b in the semiconductor package 10b shown and described above in relation to FIGS. 5 and 6, the sidewall of each of the vias 36e in the semiconductor package 10e is only plated with a conductive metal material. As further seen in FIG. 9, the conductive plating 38e of each via 36e extends from the top surface 34e of the package body 30e and covers that portion of the corresponding top contact 18e which is exposed at the bottom of the via 36e. As will be recognized by those of ordinary skill in the art, when the solder balls 50e of the top substrate 40e of the semiconductor package 10e are advanced into respective ones of the vias 36e to facilitate the mechanical and electrical connection of the top substrate 40e to the bottom substrate assembly 11e, the subsequent completion of a solder reflow process effectively fuses the solder balls 50e to the conductive plating 38e of respective ones of the vias 36e, thus in turn electrically connecting the bottom contacts 48e of the top substrate 40e to respective ones of the top contacts 18e of the bottom substrate 12e.

[0045] Referring now to FIG. 10, there shown a semiconductor package 10f constructed in accordance with a seventh embodiment of the present invention. The semiconductor package 10f is similar in construction to the semiconductor package 10b described above in relation to FIG. 6, except that the top substrate 40b of the semiconductor package 10b is substituted with a top substrate assembly 66f in the semiconductor package 10f. The top substrate assembly 66f is mechanically and electrically connected to the bottom substrate assembly 11f, which is itself identically configured to the bottom substrate assembly 11b of the semiconductor package 10b. The top substrate assembly 66f comprises a top substrate 40f which is substantially similar to the top substrate 40 of the semiconductor package 10, except that one or more electronic components such as semiconductor dies, passive devices and the like are mounted to the top surface of the top substrate 40f and electrically connected to the bottom contacts 48f disposed on the bottom surface 44f of the top substrate 40f in a prescribed pattern or arrangement. The electronic component(s) mounted to the top surface of the top substrate 40f are covered or encapsulated by a package body 68f of the top substrate assembly 66f. Thus, the top substrate assembly 66f has the general structural and functional attributes of a conventional BGA (ball grid array) semiconductor package. Those of ordinary skill in the art will recognize that a ball grid array semiconductor package like the top substrate assembly 66f included in the semiconductor package 10f may be substituted for the top substrates 40, 40a, 40b, 40c, 40d and 40e described in relation to each of the semiconductor packages 10, 10a, 10b, 10c, 10d, 10e.

[0046] Referring now to FIG. 11, there shown a semiconductor package 100 constructed in accordance with an eighth embodiment of the present invention. The semiconductor package 100 comprises a primary semiconductor die 102 which has a generally quadrangular configuration. In this regard, the primary semiconductor die 102 defines a generally planar top surface 104, an opposed generally planar bottom surface 106, and a plurality of generally planar side surfaces 108 which extend generally perpendicularly between the top and bottom surfaces 104, 106. Disposed on the bottom surface 106 of the primary semiconductor die 102 is a plurality of conductive pads or terminals.

[0047] In addition to the primary semiconductor die 102, the semiconductor package 100 comprises a secondary semiconductor die 110 which also has a generally quadrangular configuration. Conductive pads or terminals of the secondary semiconductor die 110 are electrically connected to respective ones of the pads or terminals of the primary semiconductor die 102 through the use of solder balls 112, as shown FIG. 11.

[0048] In the semiconductor package 100, subsequent to the electrical connection of the secondary semiconductor die 110 to the primary semiconductor die 102 through the use of the solder balls 112, the secondary semiconductor die 110, solder balls 112, and bottom surface 106 of the primary semiconductor die 102 are encapsulated or covered by an encapsulant material or molding compound which, upon hardening, forms a package body 114 of the semiconductor package 100. The fully formed package body 114 directly contacts the bottom surface 106 of the primary semiconductor die 102 and defines multiple, generally planar side surfaces 116 which extend in generally flush, co-planar relation to respective ones of the side surfaces 108 of the primary semiconductor die 102. In addition, the package body 114 defines a generally planar bottom surface 118.

[0049] In the semiconductor package 100, vias 120 are formed in the package body 114, with each of the vias 120 extending from the bottom surface 118 to a respective one of the conductive pads or terminals disposed on the bottom surface 106 of the primary semiconductor die 102. Like the vias 36 described above in relation to the semiconductor package 10, each of the vias 120 preferably has a generally frusto-conical configuration, and is formed by the completion of a laser drilling or similar process. In the semiconductor package 100, each of the vias 120 is completely filled with a solder ball 122. More particularly, each solder ball 122 directly contacts a respective one of the pads or terminals of the primary semiconductor die 102, and includes a portion which protrudes outwardly beyond the bottom surface 118 of the package body 114 as shown in FIG. 11. As will be recognized by those of ordinary skill in the art, the protruding portions of the solder balls 122 are used to facilitate the electrical connection of the semiconductor package 100 to an underlying substrate such as a printed circuit board.

[0050] Referring now to FIG. 12, there shown a semiconductor package 100a constructed in accordance with a ninth embodiment of the present invention. The semiconductor package 100a is substantially similar to the semiconductor package 100 described above in relation to FIG. 11, with the primary distinction lying in the package body 114a of the semiconductor package 100a being formed to be of a reduced thickness in comparison to the package body 114. As a result of the formation of the package body 114a with a reduced thickness in comparison to the package body 114, that surface of the secondary semiconductor die 110a of the semiconductor package 100a opposite that having the solder balls 112a applied thereto and disposed closest to the bottom surface 106a of the primary semiconductor die 102a is exposed in and substantially flush with the bottom surface 118a of the package body 114a. As is further seen in FIG. 12, the reduced thickness of the package body 114a also causes the solder balls 122a of the semiconductor package 100a to be smaller than the solder balls 122 included in the semiconductor package 100.

[0051] Referring now to FIG. 13, there shown a semiconductor package 100b constructed in accordance with a tenth embodiment of the present invention. The semiconductor package 100b is also similar in construction to the semiconductor package 100 shown and described above in relation to FIG. 11, with the primary distinction lying in the secondary semiconductor die 110b of the semiconductor package 100b being electrically connected to corresponding pads or terminals on the bottom surface 106b of the primary semiconductor die 102b through the use of conductive wires 124b as opposed to the use of the solder balls 112 described above in relation to the semiconductor package 100. Each of the conductive wires 124b extends from a pad or terminal of the secondary semiconductor die 110b to a corresponding pad or terminal on the bottom surface 106b of the primary semiconductor die 102b. Additionally, in the semiconductor package 100b, that surface of the secondary semiconductor die 110b opposite that to which the conductive wire 124b extend is itself secured to a central portion of the bottom surface 106b of the primary semiconductor die 102b though the use of an adhesive layer 126b. In the semiconductor package 100b, the secondary semiconductor die 110b, conductive wires 124b, and adhesive layer 126b are each covered by the package body 114b thereof.

[0052] Referring now to FIG. 14, there shown a semiconductor package 100c constructed in accordance with an eleventh embodiment of the present invention. The semiconductor package 100c is similar in structure to the semiconductor package 100 shown and described above in relation to FIG. 11. However, in the semiconductor package 100c, each of the vias 120c is not filled with a solder ball such as the solder ball 122 described in relation to the semiconductor package 100. Rather, each via 120c in the semiconductor package 100c is filled or lined with a conductive metal material (e.g., copper). Also included in the semiconductor package 100c is a plurality of conductive traces 128c which are embedded in the bottom surface 118c of the package body 114c. Each of the traces 128c, which may also be fabricated from copper, is integrally connected to the copper material filled into a respective one of the vias 120c. In fabricating the semiconductor package 100c, a laser is preferably used to ablate trenches into the bottom surface 118c of the package body 114c, such trenches being sized and configured to accommodate respective ones of the traces 128c. Additionally, formed on each of the traces 128c is a solder ball 130c which is to facilitate the electrical connection of the semiconductor package 100c to an underlying substrate such as a printed circuit board. In the semiconductor package 100c, the exposed portions of the bottom surface 118c of the package body 114c and traces 128c, as well as portions of each of the solder balls 130c, may be covered by a layer 132c of a solder mask or polymer flux.

[0053] Referring now to FIG. 15, there shown a semiconductor package 100d constructed in accordance with a twelfth embodiment of the present invention. The semiconductor package 100d is substantially similar to the semiconductor package 100c shown and described above in relation to FIG. 14. In this regard, the primary distinction between the semiconductor packages 100c, 100d lies in the traces 128d of the semiconductor package 100d being embedded in a build-up layer 134d of the semiconductor package 100d, as opposed to being embedded in the bottom surface 118d of the package body 114d thereof. In this regard, the build-up layer 134d is applied directly to the bottom surface 118d of the package body 114d. The build-up layer 134d and exposed portions of the conductive traces 128d are each covered by a solder mask layer 135d.

[0054] Referring now to FIG. 16, there shown a semiconductor package 100e constructed in accordance with a thirteenth embodiment of the present invention. The semiconductor package 100e is substantially similar in structure to the semiconductor package 100d shown and described above in relation to FIG. 15. In this regard, the primary distinction between the semiconductor packages 100d, 100e lies in the substitution of the build-up layer 134d of the semiconductor package 100d with a dielectric layer 136e in the semiconductor package 100e. The dielectric layer 136e is applied to the bottom surface 118e of the package body 114e in the semiconductor package 100e. The conductive traces 128e of the semiconductor package 100e are not embedded in the dielectric layer 136e, but rather are applied to the outer surface thereof as shown in FIG. 16. Though not shown in FIG. 16, it is contemplated that a solder mask layer may be applied over the conductive traces 128e and dielectric layer 136e, similar to the solder mask layer 135d shown in FIG. 15.

[0055] This disclosure provides exemplary embodiments of the present invention. The scope of the present invention is not limited by these exemplary embodiments. Numerous variations, whether explicitly provided for by the specification or implied by the specification, such as variations in structure, dimension, type of material and manufacturing process may be implemented by one of skill in the art in view of this disclosure.