Microelectronic package for wafer-level chip scale packaging with fan-out

Abstract

Apparatuses and methods relating generally to a microelectronic package for wafer-level chip scale packaging with fan-out are disclosed. In an apparatus, there is a substrate having an upper surface and a lower surface opposite the upper surface. A microelectronic device is coupled to the upper surface with the microelectronic device in a face-up orientation. Wire bond wires are coupled to and extending away from the upper surface. Posts of the microelectronic device extend away from a front face thereof. Conductive pads are formed in the substrate associated with the wire bond wires for electrical conductivity.

Description

FIELD

The following description relates to integrated circuit (“IC”) packaging. More particularly, the following description relates to microelectronic packages for wafer-level chip scale packaging with fan-out.

BACKGROUND

Microelectronic assemblies generally include one or more ICs, such as for example one or more packaged dies (“chips”) or one or more dies. One or more of such ICs may be mounted on a circuit platform, such as a wafer such as in wafer-level-packaging (“WLP”), printed board (“PB”), a printed wiring board (“PWB”), a printed circuit board (“PCB”), a printed wiring assembly (“PWA”), a printed circuit assembly (“PCA”), a package substrate, an interposer, or a chip carrier. Additionally, one IC may be mounted on another IC. An interposer may be an IC, and an interposer may be a passive or an active IC, where the latter includes one or more active devices, such as transistors for example, and the former does not include any active device. Furthermore, an interposer may be formed like a PWB, namely without any circuit elements such as capacitors, resistors, or active devices. Additionally, an interposer includes at least one through-substrate-via.

An IC may include conductive elements, such as pathways, traces, tracks, vias, contacts, pads such as contact pads and bond pads, plugs, nodes, or terminals for example, that may be used for making electrical interconnections with a circuit platform. These arrangements may facilitate electrical connections used to provide functionality of ICs. An IC may be coupled to a circuit platform by bonding, such as bonding traces or terminals, for example, of such circuit platform to bond pads or exposed ends of pins or posts or the like of an IC. Additionally, a redistribution layer (“RDL”) may be part of an IC to facilitate a flip-chip configuration, die stacking, or more convenient or accessible position of bond pads for example.

More recently, fan-out wafer-level chip scale packaging (“FO-WCSP”) has been used to reduce costs. Semiconductor dies are formed, such as in their smallest configurations, and these dies or a combination of different dies may then be molded together in what is known as a reconstituted wafer. This reconstituted wafer provides more surface area for interconnects using WCSP in combination with a fan-out technology, such as a lead frame, ball grid array, or other fan-out technology. This allows for a larger pitch for interconnection to a PCB or other circuit board.

Accordingly, it would be desirable and useful to provide for FO-WCSP for a package-on-package (“PoP”) configuration or other die stacking configuration.

BRIEF SUMMARY

An apparatus relates generally to a microelectronic package for wafer-level chip scale packaging with fan-out. In such an apparatus, there is a substrate having an upper surface and a lower surface opposite the upper surface. A microelectronic device is coupled to the upper surface with the microelectronic device in a face-up orientation. Wire bond wires are coupled to and extending away from a face of the microelectronic device facing away from the substrate. Posts of the microelectronic device extend away from a front face thereof. Conductive pads are formed in the substrate.

A method relates generally to forming a microelectronic package for wafer-level chip scale packaging with fan-out. In such a method, obtained is a substrate having an upper surface and a lower surface opposite the upper surface. A microelectronic device having posts is coupled in a face-up orientation to the upper surface of the substrate. Wire bond wires are bonded to the upper surface of the substrate for extending away therefrom to a height above the posts. The substrate, the microelectronic device and the wire bond wires in combination is molded with a molding material layer. An uppermost portion of the wire bond wires and an uppermost portion of the molding material layer is removed to upper ends of the posts. Conductive pads are formed in the substrate. The conductive pads are for the wire bond wires for electrical conductivity between the wire bond wires and the conductive pads associated therewith.

An apparatus relates generally to another microelectronic package for wafer-level chip scale packaging with fan-out. In such an apparatus, a substrate has an upper surface and a lower surface opposite the upper surface. The substrate includes conductive pads formed therein. Wire bond wires are coupled to and extend away from a first portion of the conductive pads along the upper surface for electrical conductivity between the wire bond wires and the first portion of the conductive pads associated therewith. A microelectronic device is coupled to a second portion of the conductive pads along the upper surface with the microelectronic device in a face-down orientation.

A method relates generally to another microelectronic package for wafer-level chip scale packaging with fan-out. In such a method, obtained is a substrate having an upper surface and a lower surface opposite the upper surface. Conductive pads are formed in the substrate. Wire bond wires are bonded to the conductive pads along the upper surface of the substrate for extending away therefrom. The conductive pads are for the wire bond wires for electrical conductivity between the wire bond wires and the conductive pads associated therewith. A microelectronic device is coupled in a face-down orientation to the upper surface of the substrate with interconnects. The substrate, the microelectronic device and the wire bond wires in combination is molded with a molding material layer.

BRIEF DESCRIPTION OF THE DRAWING(S)

Accompanying drawing(s) show exemplary embodiment(s) in accordance with one or more aspects of exemplary apparatus(es) or method(s). However, the accompanying drawings should not be taken to limit the scope of the claims, but are for explanation and understanding only.

FIGS. 1-1 through 1-9 are a progression of block diagrams of a cross-sectional side view depicting formation of an exemplary in-process microelectronic package for wafer-level chip scale package (“WCSP”) with fan-out (“FO”).

FIG. 2 is a block diagram of a top view depicting an exemplary in-process microelectronic package.

FIG. 3 is a block diagram of a top view depicting an exemplary in-process microelectronic package after forming balls on a redistribution layer (“RDL”).

FIG. 4 is a block diagram of a cross-sectional side view depicting an exemplary package-on-package (“PoP”) microelectronic package.

FIG. 5 is a block diagram of a cross-sectional side view depicting another exemplary PoP microelectronic package.

FIG. 6 is a flow diagram depicting an exemplary process flow for forming a microelectronic package for WCSP with FO.

FIGS. 7-1 through 7-6 are a progression of block diagrams of a cross-sectional side view depicting formation of another exemplary in-process microelectronic package for WCSP with fan-out FO.

FIG. 8 is a flow diagram depicting an exemplary process flow for forming another microelectronic package for WCSP with fan-out FO.

FIG. 9 is a block diagram of a cross-sectional side view depicting an exemplary PoP microelectronic package.

FIG. 10 is a block diagram of a cross-sectional side view depicting another exemplary PoP microelectronic package.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth to provide a more thorough description of the specific examples described herein. It should be apparent, however, to one skilled in the art, that one or more other examples or variations of these examples may be practiced without all the specific details given below. In other instances, well known features have not been described in detail so as not to obscure the description of the examples herein. For ease of illustration, the same number labels are used in different diagrams to refer to the same items; however, in alternative examples the items may be different.

Moreover, the features described herein as well as the numerical instances thereof are for purposes of conveying with clarity one or more aspects of exemplary apparatus(es) and/or method(s) described herein. These features are not to scale, and numerical instances thereof in an actual implementation may be the same or different from the numerical instances illustratively depicted. It should be understood that the word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any example or feature described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other examples or features.

Generally, an integrated circuit die includes a substrate of a semiconductor material such as silicon (Si), gallium arsenide (GaAs), polymeric, ceramic, carbon-based substrates such as diamond, a silicon carbon (SiC), germanium (Ge), Si_1-xGe_x, or the like. Even though a semiconductor substrate as provided from an in-process wafer is generally described below, any sheet or layer semiconductor material or dielectric material, such as ceramic or glass for example, may be used as a substrate.

A substrate includes an upper surface and a lower surface that extend in lateral directions and are generally parallel to each other at a thickness thereof. Use of terms such as “upper” and “lower” or other directional terms is made with respect to the reference frame of the figures and is not meant to be limiting with respect to potential alternative orientations, such as in further assemblies or as used in various systems.

An upper surface may generally be associated with what is referred to as a “front side” of an in-process wafer, and a lower surface may generally be associated with what is referred to as a “back side” of an in-process wafer. However, upper and lower may be reversed during processing. Along those lines, a front-side of an in-process wafer may be used for forming what is referred to as front-end-of-line (“FEOL”) structures and back-end-of-line (“BEOL”) structures. Generally, FEOL structures may include shallow trench isolations (“STI”), transistor gates, transistor source/drain regions (not shown), transistor gate dielectrics (not shown), contact etch stop layer (“CESL”; not shown), a pre-metallization dielectric or pre-metal dielectric (“PMD”), and contact plugs, among other FEOL structures. A PMD may be composed of one or more layers. Generally, BEOL structures may include one or more inter-level dielectrics (“ILDs”) and one or more levels of metallization (“M”). Each ILD may be composed of one or more dielectric layers, and each metal or metallization level may be composed of one or more metal layers, as well as one or more barrier and/or liner layers. Additionally, metal from a metallization level may extend through one or more ILDs, as is known. A passivation level may be formed on a last metallization layer. Such passivation level may include one or more dielectric layers, and further may include an anti-reflective coating (“ARC”). Furthermore, a redistribution layer (“RDL”) may be formed on such passivation level. Conventionally, an RDL may include: a dielectric layer, such as a polyimide layer for example; another metal layer on such dielectric layer connected to a bond pad of a metal layer of a last metallization level; and another dielectric layer, such as another polyimide layer for example, over such RDL metal layer while leaving a portion thereof exposed to provide another bond pad. A terminal opening may expose such other bond pad of such RDL metal layer. Thereafter, a solder bump or wire bond may be conventionally coupled to such bond pad.

Balls or other discrete interconnects may be respectively formed on bonding pads, where such pads may be formed on or as part of metal layer. Balls may be formed of a bonding material, such as solder or other bonding material. Balls may be microbumps, C4 bumps, ball grid array (“BGA”) balls, or some other die interconnect structure. In some applications, metal layer may be referred to as a landing pad. BGA, lead frame, and other types of interconnects may be used as fan-out technologies.

The following description is for fan-out wafer-level chip scale packaging (“FO-WCSP for a stacked or 3D device, such as for a package-on-package PoP device. Along those lines, wire bond wires are used for interconnection with an upper package of a PoP device. Use of wire bond wires as described below may eliminate a substrate and/or corresponding through substrate vias used in a conventionally manufactured PoP device with fan-out. Thus, a lower cost and thinner PoP device with fan-out may be manufactured using wire bond wires as described hereinbelow. Along those lines, a PoP device with fan-out using wire bond wires, such as of a BVA™ technology, may be used in mobile devices and other small form factor applications.

FIGS. 1-1 through 1-9 (collectively and singly “FIG. 1”) are a progression of block diagrams of a cross-sectional side view depicting formation of an exemplary in-process microelectronic package 100 for wafer-level chip scale package (“WCSP”) with fan-out (“FO”). FIGS. 1, 4 and 5 hereof are described with simultaneous reference to FIG. 6, where there is shown a flow diagram depicting an exemplary process flow 600 for forming a microelectronic package 100 for WCSP with FO.

At 601, a substrate having an upper surface and a lower surface opposite the upper surface is obtained. With reference to FIG. 1-1, in-process microelectronic package 100 includes a carrier 101 coupled to a foil substrate layer 103 with a releasable adhesive 102. In this example implementation, carrier 101 is a copper carrier, and foil substrate layer 103 is copper foil layer. However, in other implementations, carrier 101 may be silicon, glass, laminate, or other dielectric and/or metal carrier material. Carrier 101 may or may not be opaque, such as with respect to UV rays for example. Along those lines, releasable adhesive 102 may be a thermal or UV released adhesive for example. Moreover, in other implementations, foil substrate layer 103 may be another electrical conductor, such as gold, platinum or other thin film metal for example. Foil substrate layer (“substrate”) 103 has an upper surface 104 and a lower surface 105 opposite such upper surface 104.

At 602, wire bond wires may be bonded to the upper surface of the substrate for extending away therefrom to a height above posts of a microelectronic device. With reference to FIG. 1-2, wire bond wires 110 are coupled to and extend away from upper surface 104. In this example, copper wire bond wires 110 are used. However, in another implementation, another form of wire bond wires 110 may be used, such as aluminum, silver, gold, palladium-coated copper (“PCC”), core wires, or other forms of wire bond wire. Wire bond wires 110 may be BVA™ bonded wires. Columns and/or rows (“rows”) 112 of wire bond wires 110 may be spaced apart from one another to define a region 111 and may be coupled to upper surface 104.

In this example, wire bond wires 110 are ball bonded with corresponding ball bonds 113 to upper surface 104. However, in another implementation, stitch, wedge, compliant, or other forms of BVA bonding may be used. For this implementation, which does not use soldering of wire bond wires 110, copper wire bond wires 110 may be attached with ball bonds to upper surface 104 of substrate 103 for substrate-to-upper package routing.

In another example, a “wired-arch” or “wired-loop” wire bond wire 114 may be formed on upper surface 104 such that a first bond, such as a ball bond 113 for example, is formed at a first location on upper surface 104 and a second bond, such as a wedge or stitch bond 144, is formed at a second location on upper surface 104 spaced apart from such first location by at least approximately 10-400 microns for example. An upper surface 134 of such a “wired-arch” wire bond wire 114 may be used for interconnection, as described elsewhere herein. However, for purposes of clarity by way of example and not limitation, generally only wire bond wires 110, and not wired-arch wire bond wires 114, are further described.

Ball bonds 113, as well as wire bond wires 110 drawn therefrom, may be spaced apart from one another. Even though only single rows 112 spaced apart from one another are illustratively depicted in FIG. 1-2, in other implementations one or more rows 112 may be on one or more sides of region 111 defined by such rows 112. However, for purposes of clarity by way of example and not limitation, it shall be assumed that a single row 112 is located on each side of region 111 for defining such region for receipt of a microelectronic device. Moreover, wire bond wires 110 may extend to a height above posts of such a microelectronic device, as described below in additional detail.

At 603, a microelectronic device having posts may be coupled in a face-up orientation to the upper surface of the substrate. In another implementation, operations at 602 and 603 may be in reverse order. With reference to FIG. 1-3, a microelectronic device 115 may be coupled to upper surface 104 with an adhesive or an underfill 116 in region 111. Microelectronic device 115 may be spaced apart from ball bonds 113 after coupling to upper surface 104. Adhesive 116 may be a compliant material after curing, such as a polyimide (“PI”) or a polybenzoxazole (“PBO”) for example, with a modulus of elasticity of less than approximately 4 gigapascals (“GPa”).

Microelectronic device 115 may be coupled to upper surface 104 in a face-up or front side up orientation. Generally, a face of microelectronic device 115 having posts extending away therefrom, such a face may be facing away from such substrate to which microelectronic device 115 is coupled in this implementation. Even though wire bond wires 110 are attached to upper surface 104 in this example prior to coupling microelectronic device 115, this order may be reversed in this or another implementation. Microelectronic device 115 may be a packaged or bare integrated circuit die formed using a Si, GaAs, or other semiconductor wafer. Optionally, microelectronic device 115 may be a passive device.

Along an upper surface 118 of microelectronic device 115, conductive posts or pads 117 of microelectronic device 115 extend away from a front side or face thereof, namely upper surface 118. In this example, upper ends 122 of electrically conductive posts or pads 117 are over and above an upper surface 118 of microelectronic device 115. In this example, copper posts or pads 117 are used. However, in another example, another type of electrically conductive material may be used for posts or pads 117. Furthermore, a structure other than posts or pads 117, such as stud bumps for example, may be attached along upper surface 118 of microelectronic device 115. Stud bumps may be a ball bonds, such as a ball bond-only portion of wire bonds. Additionally, posts or pads 117 may be formed with a metalization layer used in forming microelectronic device 115. For purposes of clarity by way of example and not limitation, it shall be assumed that copper posts 117 are used for interconnects.

Even though a single instance of an exemplary in-process microelectronic package 100 is illustratively depicted, two or more of such in-process microelectronic packages 100 may be used. In another example, such in-process microelectronic package 100 may be a portion of a reconstituted wafer having multiple in-process microelectronic packages 100. A reconstituted wafer typically consist of dies coupled to one another by a molding material in-between them to form a wafer or substrate.

At 604, the substrate, the microelectronic device and the wire bond wires assemblage or combination may be molded with a molding material layer, which may include grinding or polishing of a surface of such molding material layer. With reference to FIG. 1-4, a molding material layer 120 may be formed over upper surface 104, microelectronic device 115 and wire bond wires 110. In this example, tips or upper ends 123 of wire bond wires 110 are above an upper surface 124 of molding material layer 120. For a wired-arch wire bond wire 114, an upper surface 134 of such a wire arch 114 may be embedded or protrude above an upper surface 124 of molding material layer 120. Along those lines, wire bond wires 110 may extend above upper ends 122 of posts 117. Thus, while tips 123 of wire bond wires 110, or upper surface 134 of wired-arch wire bond wires 114, may be exposed after forming molding material layer 120, upper ends 122 of post 117 are covered by molding material layer 120. In another implementation, molding layer 120 may cover tips 123, or upper surfaces 134, as generally indicated by dashed line 121. For purposes of clarity by way of example and not limitation, it shall be assumed that tips 123 are exposed after forming molding material layer 120. Molding material layer 120 may be for forming a reconstituted wafer having multiple in-process microelectronic packages 100.

With reference to FIG. 1-5, after molding, carrier 101 may be removed along with adhesive 102. Again, adhesive 102 may be a releasable adhesive using temperature, UV rays, and/or other releasing agent.

With reference to FIG. 1-6, molding material layer 120, as well as tips 123 of wire bond wires 110, may be ground or polished down to expose upper ends 122. Removal of material such as by grinding may occur before or after removal of carrier 101. After grinding, upper ends 130 of wire bond wires 110, as well as upper ends 122 of posts 117, may be exposed for interconnections respectively thereto. However, after grinding, molding material layer 120 may be left in place around posts 117 and remaining portions of wire bond wires 110. For a wired-arch wire bond wire 114, after grinding of upper surface 134 of such a wire arch 114, first and second bonds thereof may be electrically disconnected from one another for example by grinding a protruding upper surface 134 to cause a break in such wire arch 114 leaving two at least temporarily exposed upper ends along upper surface 134. Along those lines, grinding may effectively form two separate wire bonds with different bond types, for example a ball bond 113 and a wedge or stitch bond 144.

With reference to FIG. 2, where there is shown a block diagram of a top view depicting an exemplary in-process microelectronic package 100. For this implementation, upper surface 124 may be generally co-planar with upper ends 122 and 130 after grinding. Posts 117 may be in region 111 defined by rows and columns of wire bond wires 110 surrounding microelectronic device 115.

At 605, the wire bond wires and the posts may be interconnected with a redistribution layer. With reference to FIG. 1-7, a redistribution layer (“RDL”) 135 may be formed with a bottom surface thereof interconnected to upper ends 122 of posts 117 and upper ends 130 of wire bond wires 110 for interconnecting at least a portion of wire bond wires 110 with at least a portion of posts 117. Even though a single layer of a dielectric layer 137 and a conductive layer 136 is illustratively depicted for RDL 135, in other implementations, RDL 135 may include one or more dielectric and conductive layers. Along those lines, an integrated circuit die may be interconnected to conductive pads on a lower surface of a substrate, as described below in additional detail.

RDL 135 may be entirely formed on upper surface 124 of molding material layer 120, as well as being interconnect to upper ends 130 of wire bond wires 110 and to upper ends 122 of posts 117. In a conventional FOWLP package, an RDL is formed on top of a Si substrate and then surrounded with molding material, and so a large stress field is developed around a transition area or “triple point” where such RDL, Si substrate and molding material intersect. In contrast, by covering an area of a microelectronic device 115 with molding material layer 120 as described herein, RDL 135 avoids a conventional “triple point.”

Traces or pads 169 of conductive layer 136 may interconnect upper ends 122 of posts 117 and upper ends 130 of wire bond wires 110. Accordingly, wire bond wires 110 may provide “vertical interconnects” along sides of a microelectronic device for interconnecting substrate 103 and RDL 135. Such wire bond wires 110 may additionally be interconnected to corresponding posts 117 of microelectronic device 115.

At 606, conductive pads may be formed in the substrate electrically isolated from a remainder of the substrate, where the conductive pads correspond to the wire bond wires for electrical conductivity between the wire bond wires and the conductive pads corresponding thereto. With reference to FIG. 1-8, in-process microelectronic package 100 may be flipped for patterning and etching a lower surface 105 of substrate 103, namely a back side of microelectronic package 100. In another implementation, a direct write etch may be used on lower surface 105.

Through substrate channels 142 may be formed from lower surface 105 to upper surface 104 with a stop molding layer 120 for example. Through substrate channels 142 may be at least partially, if not completely, filled with a dielectric material 143, such as a polyimide for example. Conductive pads 140 may be defined by such through substrate channels 142 in copper substrate 103 for this example implementation. Conductive pads or conductive islands 140 may have previously been coupled to wire bond wires 110, as previously described with reference to bonding to upper surface 104 of substrate 103. Conductive pads 140 may be defined in substrate 103 as respective islands of a material of such substrate. Even though conductive pads 140 are illustratively depicted near an outer edge of microelectronic package 100, conductive pads 140 may be formed in generally a middle region (“remainder”) 141, such as directly below microelectronic device 115 for example.

Conductive pads 140 may be formed using substrate 103 material for electrical isolation from a remainder 141 of substrate 103. Such remainder 141 may be used as a ground plane. In some instances, no conductive pad 140 may be associated with a wire bond wire 110 for coupling to a ground plane, or other voltage plane. Conductive pads 140 corresponding to wire bond wires 110 for electrical conductivity therebetween may be used for electrical communication with microelectronic package 100 and/or another microelectronic package as described below in additional detail. Although not illustratively depicted in FIG. 1, another redistribution layer RDL may be formed on a top surface of substrate 103. This RDL, like RDL 135, may include one or more dielectric and conductive layers.

At 607, first interconnects may be attached to a top surface of the redistribution layer for electrical conductivity with the posts and the wire bond wires. With reference to FIG. 1-9, balls or bumps 145 may be formed on exposed surfaces of traces or pads 169 of conductive layer 136. Such balls or bumps 145 may be mechanically isolated from electrical conductivity by one or more dielectric layers 137 of an RDL 135. However, such conductive traces or pads 169 of conductive layer 136 may be coupled for electrical conductivity with wire bond wires 110, as well as one or more posts 117, as previously described. Balls or bumps 145 for interconnection with posts 117 and not wire bond wires 110 are not illustratively depicted in this figure for purposes of clarity and not limitation.

With reference to FIG. 3, where there is shown a block diagram of a top view depicting an exemplary in-process microelectronic package 100 after forming balls 145 on RDL 135. Some of balls 145 may be associated with pads or traces 169 of conductive layer 136 for coupling to wire bond wires. Others of balls 145 may be associated with pads or traces 169 of conductive layer 136 not associated with wire bond wires 110 and associated with posts 117. Moreover, even though generally a one-to-one correspondence between wire bond wires 110 coupled to posts 117 is illustratively depicted, wire bond wires 110 may be interconnected to more than one post 117. In one or more instances, there may not be a direct coupling for an electrical connection between at least one wire bond wire 110 and at least one post 117.

Pitch 148 of pads 169 of conductive layer 136 for balls 145 associated with wire bond wires 110 may be in a range of approximately 350 to 600 microns or less for correspondence with pitch of contacts on a PCB or other circuit board. Along those lines, minimum pitch of posts 117 and wire bond wires 110 may be as small as 5 microns and as small as 20 microns, respectively. An RDL 135 may effectively cause pitch 148 to be at least approximately the same as for example a BGA pitch of a circuit board, such as approximately 350 microns.

At 608, second interconnects of another microelectronic device may be coupled to the conductive pads for electrical conductivity with the wire bond wires. With reference to FIG. 4, there is shown a block diagram of a cross-sectional side view depicting an exemplary PoP microelectronic package 300. In this example, a microelectronic package 100, which may still be in a reconstituted wafer or may be diced therefrom, has coupled on the back side thereof another microelectronic package 200. In other words, PoP microelectronic package 300 may be package-to-package assembled, package-to reconstituted wafer assembled, or wafer/reconstituted wafer to reconstituted wafer assembled, with the last three involving subsequent dicing. In this example, microelectronic devices 115 and 201 are respective packaged integrated circuit dies; however, in another example either or both microelectronic devices 115 and 201 may be bare integrated circuit dies. In an example, microelectronic package 100 may be an applications processor or a baseband processor or any other logic device, and microelectronic package 200 may be a memory device, such as with one or more types of memory die including NAND, DRAM, memory controller, and/or the like.

Bumps or balls 155 of microelectronic package 200 may be physically coupled to conductive pads 140 of microelectronic package 100 for electrical conductivity between microelectronic packages 100 and 200. PoP microelectronic package 300 may be coupled to a PCB or other circuit board 160 which is not part of PoP microelectronic package 300. Overall height 400 of PoP microelectronic package 300 may be approximately 1.5 mm or less. Optionally, an underfill (not shown) may be injected between microelectronic packages 100 and 200.

With reference to FIG. 5, there is shown a block diagram of a cross-sectional side view depicting another exemplary PoP microelectronic package 300. In this example, a microelectronic package 100, which may still be in a reconstituted wafer or may be diced therefrom, has formed on a back side thereof another RDL 165. Another microelectronic package 200 may be coupled to an optional RDL 165. Along those lines, a bottom surface of RDL 165 may be interconnected to conductive pads 140 of microelectronic package 100 for electrical conductivity therewith. Either or both of RDLs 135 and/or 165 may have one or more metal layers and/or one or more dielectric layers.

Bumps or balls 155 of microelectronic package 200 may be physically coupled to conductive pads 164 of RDL 165 of microelectronic package 100 for electrical conductivity between microelectronic packages 100 and 200. PoP microelectronic package 300 may be coupled to a PCB or other circuit board 160 not part of PoP microelectronic package 300. Overall height 400 of PoP microelectronic package 300 may be approximately 1.5 mm or less. Wire bond wires 110 may be disposed around a perimeter of microelectronic device 115, which may be packaged integrated circuit die or a bare integrated circuit die.

FIGS. 7-1 through 7-6 (collectively and singly “FIG. 7”) are a progression of block diagrams of a cross-sectional side view depicting formation of another exemplary in-process microelectronic package 100 for WCSP with fan-out FO. FIGS. 7, 9 and 10 are hereafter described with simultaneous reference to FIG. 8, where there is shown a flow diagram depicting an exemplary process flow 800 for forming such other microelectronic package 100 for WCSP with fan-out FO.

At 601, a substrate having an upper surface and a lower surface opposite the upper surface is obtained. With reference to FIG. 7-1, in-process microelectronic package 100 includes a carrier 101 coupled to a foil substrate layer 103 with a releasable adhesive 102. In this example implementation, carrier 101 is a copper carrier, and foil substrate layer 103 is copper foil layer. However, in other implementations, carrier 101 may be silicon, glass, laminate, or other metal and/or dielectric carrier material. Carrier 101 may or may not be opaque, such as with respect to UV rays for example. Along those lines, releasable adhesive 102 may be a thermal or UV released adhesive for example. Moreover, in other implementations, foil substrate layer 103 may be another electrical conductor, such as gold, platinum or other thin film metal for example. Foil substrate layer (“substrate”) 103 has an upper surface 104 and a lower surface 105 opposite such upper surface 104.

At 802, conductive pads or conductive islands may be formed in the substrate electrically isolated from a remainder of the substrate. The conductive pads may correspond to the wire bond wires for electrical conductivity between the wire bond wires and the conductive pads corresponding thereto as described below in additional detail.

With reference to FIG. 7-1, in-process microelectronic package 100 may have an upper surface 104 of substrate 103 directly written with a laser drill. In another implementation, patterning and etching may be used on upper surface 104. Through substrate channels 142 may be formed from upper surface 104 down to lower surface 105.

Through substrate channels 142 may be at least partially, if not completely, be filled with a dielectric material 143, such as a polyimide for example. Conductive pads 140 may be defined by such through substrate channels 142 in copper substrate 103 for this example implementation. Conductive pads 140 may be defined in substrate 103 as respective islands of a material of such substrate. In another implementation, substrate channels 142 may not be filled with any material, and conductive pads 140 may only be attached to carrier 101 via adhesive 102.

Conductive pads 140 may be formed using substrate 103 material for electrical isolation from a remainder of substrate 103, and such remainder of substrate 103 not used for conductive pads 140 may be used as a ground plane (not shown in this figure). However, for a face-down configuration as described with reference to FIG. 7 for example, conductive pads 140 may be formed for interconnection with posts or pads 117 of a microelectronic device 115, as described below in additional detail.

At 803, wire bond wires may be bonded to the upper surface of the substrate for extending away therefrom to a height above a microelectronic device, as described below in additional detail. With reference to FIG. 7-2, wire bond wires 110 are coupled to and extend away from upper surface 104. In this example, copper wire bond wires 110 are used. However, in another implementation, another form of wire bond wires 110 may be used, such as aluminum, silver, gold, palladium-coated copper (“PCC”), core wires, or other forms of wire bond wire. Wire bond wires 110 may be BVA™ bonded wires.

Again, in another example, a “wired-arch” or “wired-loop” wire bond wire 114 may be formed on upper surface 104 such that a first bond, such as a ball bond 113 for example, is formed at a first location on upper surface 104 and a second bond, such as a wedge or stitch bond 144, is formed at a second location on upper surface 104 spaced apart from such first location by at least approximately 10 microns for example. An upper surface 134 of such a “wired-arch” wire bond wire 114 may be used for interconnection, as described elsewhere herein. However, for purposes of clarity by way of example and not limitation, generally only wire bond wires 110, and not wired-arch wire bond wires 114, are further described.

Columns and/or rows (“rows”) 112 of wire bond wires 110 may be spaced apart from one another to define a region 111 and may be coupled to upper surface 104. Such spacing between wire bond wires 110 may, though need not be uniform. For example, a denser spacing may be used in some locations as compared with other locations, as may vary from application to application depending on routing. Moreover, routing, including via RDL, may be denser in some areas as compare with other areas corresponding to layout of an integrated circuit die. Having the flexibility to have wire bond wires 110 use different spacings may be useful to accommodate shorter path distances and/or pin layout of a package.

In this example, wire bond wires 110 are ball bonded with corresponding ball bonds 113 to conductive pads 140 along upper surface 104. However, in another implementation, stitch, wedge, compliant, or other forms of BVA bonding may be used. For this implementation, which does not use soldering of wire bond wires 110, copper wire bond wires 110 may be attached with ball bonds to upper surface 104 of substrate 103 for substrate-to-upper package routing.

In some instances, no conductive pad 140 may be associated with a wire bond wire 110, such as for coupling to a ground plane or other voltage plane. Conductive pads 140 corresponding to wire bond wires 110 for electrical conductivity therebetween may be used for electrical communication with microelectronic package 100 and/or another microelectronic package as described below in additional detail.

Ball bonds 113, as well as wire bond wires 110 drawn therefrom, may be spaced apart from one another. Even though only single rows 112 spaced apart from one another are illustratively depicted in FIG. 7-2, in other implementations one or more rows 112 may be on one or more sides of region 111 defined by such rows 112. However, for purposes of clarity by way of example and not limitation, it shall be assumed that a single row 112 is located on each side of region 111 for defining such region for receipt of a microelectronic device. Moreover, wire bond wires 110 may extend to a height above a back side surface of such a microelectronic device, as described below in additional detail.

At 804, a microelectronic device having posts may be coupled in a face-down orientation to the upper surface of the substrate with first interconnects. In another implementation, operations at 803 and 804 may be in reverse order. Optionally, microelectronic device 115 may be coupled to an upper surface 104 by injecting an underfill 168 prior to molding.

With reference to FIG. 7-3, a microelectronic device 115 may be coupled to upper surface 104 in region 111. A microelectronic device 115 may be a bare IC or a packaged IC. Even though a single instance of an exemplary in-process microelectronic package 100 is illustratively depicted, two or more such in-process microelectronic packages 100 may be used. In another example, such in-process microelectronic package 100 may be a portion of a reconstituted wafer having multiple in-process microelectronic packages 100.

Microelectronic device 115 may be spaced apart from ball bonds 113 after coupling to upper surface 104. Posts or pads 117 may be coupled to corresponding conductive pads 140 by bonding, such as copper-to-copper as in this example. Accordingly, soldering may be avoided for this interconnection by having copper conductive pads 140 aligned with lower surfaces of posts 117. Although a copper-to-copper bond is illustratively depicted in FIG. 7, in another implementation a conventional reflow bond using a solder material may be used.

Along a lower front side surface of microelectronic device 115, conductive posts or pads 117 may extend away therefrom. In this example, lower ends of electrically conductive posts or pads 117 are over and above conductive pads 140 of microelectronic device 100. In this example, copper posts or pads 117 are used. However, in another example, another type of electrically conductive material may be used for posts or pads 117. Additionally, posts or pads 117 may be formed with a metalization layer used in forming microelectronic device 115. For purposes of clarity by way of example and not limitation, it shall be assumed that copper posts 117 are used for interconnects.

With reference to FIG. 7-4, microelectronic device 115 may be further coupled to upper surface 104 in a face-down or front side down orientation with an adhesive 716. Adhesive 716 may be injected between posts or pads 117 underneath microelectronic device 115. Additionally, adhesive 716 may extend into gaps between near surfaces of wire bond wires 110 and sidewalls of microelectronic device 115. Adhesive 716 may be deposited on a back side surface 724 of a packaged die or bare die integrated circuit of microelectronic device 115. Tips 123 of wire bond wires 110 may be above (i.e., higher than) an upper surface 725 of adhesive 716, or at least higher than back side surface 724. In another example, adhesive 716 may be an epoxy mold compound. In yet another example, adhesive 716 may be an underfill material which may extend into gaps between near surfaces of wire bond wires 110 and sidewalls of microelectronic device 115.

At 805, the substrate, the microelectronic device and the wire bond wires assemblage or combination may be molded with a molding material layer, which may include grinding or polishing such molding material layer. With reference to FIG. 7-5, a molding material layer 120 is formed over upper surface 104, microelectronic device 115, and wire bond wires 110. In this example, tips or upper ends 123 of wire bond wires 110 are above an upper surface 124 of molding material layer 120. Thus, tips 123 of wire bond wires 110 may be exposed after forming molding material layer 120. Surfaces 724 or 725 may or may not be covered by molding material layer 120. In another implementation, molding layer 120 may cover tips 123 followed by a grind or etch back to reveal upper ends of wire bond wires 110. For purposes of clarity by way of example and not limitation, it shall be assumed that tips 123 are exposed after forming molding material layer 120. Molding material layer 120 may be for forming a reconstituted wafer having multiple in-process microelectronic packages 100.

For a wired-arch wire bond wire 114, an upper surface 134 of such a wire arch 114 may be embedded or protrude above an upper surface 124 of molding material layer 120. After molding, carrier 101 may be removed along with adhesive 102. Again, adhesive 102 may be a releasable adhesive with temperature, UV rays, and/or other releasing agent.

In another implementation, molding material layer 120, as well as tips 123 of wire bond wires 110, or an upper arched surface 134 of wired-arch wire bond wires 114, may be ground or polished down to an upper surface 724 or 725. Removal of material such as by grinding may occur before or after removal of carrier 101. After grinding, upper ends 130, such as in FIG. 1-6, of wire bond wires 110 may be exposed for interconnections respectively thereto in such an implementation. After grinding, molding material layer 120 may be left in place around posts 117 and remaining portions of wire bond wires 110. However, for purposes of clarity by way of example and not limitation, it shall be assumed that tips 123 extend above an upper surface 124 of molding material layer 120, and that grinding of tips 123 is not used. For a wired-arch wire bond wire 114, after grinding of upper surface 134 of such a wire arch 114, first and second bonds thereof may be electrically disconnected from one another for example by grinding a protruding upper surface 134 to cause a break in such wire arch 114 leaving two at least temporarily exposed upper ends along upper surface 134. Along those lines, grinding may effectively form two separate wire bonds with different bond types, for example a ball bond 113 and a wedge or stitch bond 144.

At 806, the wire bond wires and the first interconnects may be interconnected via the conductive pads with a redistribution layer, where the redistribution layer has a first surface in contact with the conductive pads for the interconnecting. With reference to FIG. 7-6, an RDL 135 may be formed with a bottom surface thereof interconnected to upper surfaces of conductive pads 140 for interconnecting at least a portion of wire bond wires 110 with at least a portion of posts 117. Even though a single dielectric layer 137 and a single conductive layer 136 are illustratively depicted for RDL 135, in other implementations RDL 135 may include one or more dielectric and conductive layers. Along those lines, a PCB or other circuit board may be interconnected to RDL 135, as described below in additional detail.

Traces or pads 169 of conductive layer 136 may interconnect upper surfaces of conductive pads 140 for coupling upper ends of wire bond wires 110 and posts 117 to one another. Accordingly, wire bond wires 110 may provide “vertical interconnects” along sides of a microelectronic device 115 for interconnecting substrate 103 and RDL 135.

At 807, second interconnects may be attached to a second surface opposite the first surface of the redistribution layer. With continued reference to FIG. 7-6, balls or bumps 145 may be formed on exposed surfaces of traces or pads 169 of conductive layer 136. Such balls or bumps 145 may be mechanically isolated from electrical conductivity by one or more dielectric layers 137 of an RDL 135. However, such conductive traces or pads 169 of conductive layer 136 may be coupled for electrical conductivity with wire bond wires 110, as well as one or more posts 117, as previously described. Balls or bumps 145 for interconnection with posts 117 and not wire bond wires 110 are not illustratively depicted in this figure for purposes of clarity and not limitation.

At 808, third interconnects of another microelectronic device may be coupled to the conductive pads for electrical conductivity with the wire bond wires. With reference to FIG. 9, there is shown a block diagram of a cross-sectional side view depicting an exemplary PoP microelectronic package 300. In this example, a microelectronic package 100, which may still be in a reconstituted wafer or may be diced therefrom, has coupled on a back side thereof another microelectronic package 200. In other words, PoP microelectronic package 300 may be package-to-package assembled, package-to reconstituted wafer assembled, or wafer/reconstituted wafer to reconstituted wafer assembled, with the last three involving subsequent dicing. In this example, microelectronic devices 115 and 201 are respective packaged integrated circuit dies; however, in another example either or both microelectronic devices 115 and 201 may be bare integrated circuit dies.

Bumps or balls 155 of microelectronic package 200 may be physically coupled to tips 123, or upper surfaces 130 in another implementation, of wire bond wires 110 of microelectronic package 100 for electrical conductivity between microelectronic packages 100 and 200. PoP microelectronic package 300 may be coupled to a PCB or other circuit board 160 not part of PoP microelectronic package 300. Overall height 400 of PoP microelectronic package 300 may be approximately 1.5 mm or less. Optionally, an underfill (not shown) may be injected between microelectronic packages 100 and 200. For example, using BVA pins or wire tips 123 may thus avoid having to introduce another metal layer, such as another copper layer on a back side surface, such as either of surfaces 724 or 725 of FIG. 7-4, for example. Again, wire bond wires 110 may be disposed around a perimeter of microelectronic device 115.

With reference to FIG. 10, there is shown a block diagram of a cross-sectional side view depicting another exemplary PoP microelectronic package 300. In this example, a microelectronic package 100, which may still be in a reconstituted wafer or may be diced therefrom, has formed on a back side thereof another RDL 165. Another microelectronic package 200 may be coupled to an optional RDL 165. Along those lines, a bottom surface of RDL 165 may be interconnected to upper surfaces 130 of wire bond wires 110 of microelectronic package 100 for electrical conductivity therewith. Along those lines, tips 123 of FIG. 7-5 may be ground down to surface 124 for example.

Bumps or balls 155 of microelectronic package 200 may be physically coupled to conductive pads 164 of RDL 165 of microelectronic package 100 for electrical conductivity between microelectronic packages 100 and 200. PoP microelectronic package 300 may be coupled to a PCB or other circuit board 160 not part of PoP microelectronic package 300. Overall height 400 of PoP microelectronic package 300 may be approximately 1.5 mm or less.

While the foregoing describes exemplary embodiment(s) in accordance with one or more aspects of the invention, other and further embodiment(s) in accordance with the one or more aspects of the invention may be devised without departing from the scope thereof, which is determined by the claim(s) that follow and equivalents thereof. Claim(s) listing steps do not imply any order of the steps. Trademarks are the property of their respective owners.

Claims

1. A package-on-package device for wafer-level chip scale packaging with fan-out, comprising: a metal substrate having an upper surface and a lower surface opposite the upper surface;the substrate including outer conductive pads and inner conductive pads formed therein from material of the substrate electrically isolated from one another and from a remainder of the substrate;lower ends of wire bond wires directly coupled to the outer conductive pads along the upper surface for electrical conductivity between the wire bond wires and the outer conductive pads associated therewith;lower ends of first interconnects directly coupled to the inner conductive pads along the upper surface for electrical conductivity between the first interconnects and the inner conductive pads;a redistribution layer having second interconnects coupled to the outer and the inner conductive pads along the lower surface for electrical conductivity between the outer and the inner conductive pads; anda microelectronic device directly coupled to upper ends of the first interconnects for electrical conductivity, wherein the outer conductive pads are located outside of a perimeter of the microelectronic device for the fan-out from the inner conductive pads located below the microelectronic device.

2. The package-on-package device according to claim 1, wherein the remainder of the substrate is a ground plane.

3. The package-on-package device according to claim 1, wherein the redistribution layer is a first redistribution layer, the package-on-package device further comprising a second redistribution layer with a bottom surface thereof interconnected to upper ends of the wire bond wires for electrical conductivity.

4. The package-on-package device according to claim 3, wherein the microelectronic device is a first microelectronic device, the package-on-package device further comprising: a second microelectronic device interconnected to a top surface of the second redistribution layer for electrical conductivity to the upper ends of the wire bond wires through the second redistribution layer; andwherein the first interconnects are posts.

5. The package-on-package device according to claim 1, further comprising a molding material layer disposed around the posts and the microelectronic device.

6. The package-on-package device according to claim 5, wherein the molding material layer is a first molding material layer, the package-on-package device further comprising a second molding material layer disposed around the wire bond wires.