Patent ID: 12238865

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

Embodiments will be described with respect to embodiments in a specific context, namely a standalone three dimensional (3D) integrated fan-out (InFO) package and printed circuit board (PCB) structure installed in a cover and suitable for use, for example, with home appliances. Other embodiments may be suitable for other applications. For example, some embodiments may be suitable for medical devices, home automation, geographic location services, mobile communications, and marketing applications. Many different embodiments and applications are possible.

An integrated circuit structure and methods of forming the same are provided in accordance with various exemplary embodiments. The intermediate stages of forming the integrated circuit structure are illustrated and variations of embodiments are discussed.

FIGS.1-7illustrate cross-sectional views of intermediate steps in forming an integrated circuit structure in accordance with some embodiments. Referring first toFIG.1, there is shown a carrier substrate100and buffer layer102. Generally, the carrier substrate100provides temporary mechanical and structural support during subsequent processing steps. The carrier substrate100may include any suitable material, such as, for example, silicon based materials, such as a silicon wafer, glass or silicon oxide, or other materials, such as aluminum oxide, a ceramic material, combinations of any of these materials, or the like. In some embodiments, the carrier substrate100is planar in order to accommodate further processing.

An optional release layer (not shown) may be formed over the carrier substrate100that may allow easier removal of the carrier substrate100. As explained in greater detail below, various layers and devices will be placed over the carrier substrate100, after which the carrier substrate100may be removed. The optional release layer aids in the removal of the carrier substrate100, reducing damage to the structures formed over the carrier substrate100. The release layer may be formed of a polymer-based material. In some embodiments, the release layer is an epoxy-based thermal release material, which loses its adhesive property when heated, such as a Light-to-Heat-Conversion (LTHC) release coating. In other embodiments, the release layer may be an ultra-violet (UV) glue, which loses its adhesive property when exposed to UV light. The release layer may be dispensed as a liquid and cured. In other embodiments, the release layer may be a laminate film laminated onto the carrier substrate100. Other release layers may be utilized.

Buffer layer102is formed over carrier substrate100. Buffer layer102is a dielectric layer, which may be a polymer (such as polybenzoxazole (PBO), polyimide, benzocyclobutene (BCB), or the like), a nitride (such as silicon nitride or the like), an oxide (such as silicon oxide, PhosphoSilicate Glass (PSG), BoroSilicate Glass (BSG), Boron-doped PhosphoSilicate Glass (BPSG), or a combination thereof, or the like), or the like, and may be formed, for example, by spin coating, lamination, Chemical Vapor Deposition (CVD), or the like. In some embodiments, buffer layer102is a planar layer, within process variations, having a uniform thickness, wherein the thickness may be between about 5 μm and about 20 μm. The top and the bottom surfaces of buffer layer102are also planar, within process variations.

FIG.2illustrates attaching a plurality of integrated circuit dies200to the backside of buffer layer102in accordance with some embodiments. In some embodiments, the integrated circuit dies200may be adhered to buffer layer102by an adhesive layer204, such as a die-attach film (DAF). In an embodiment, the die-attach film204may only be located directly below the integrated circuit dies200as shown inFIG.2. In other embodiments, the die-attach film204may extend over the buffer layer102between adjacent integrated circuit dies200. A thickness of the adhesive layer may be in a range from about 5 μm to about 50 μm, such as about 20 um. Any number of integrated circuit dies200may be used, and integrated circuit dies200may include any die suitable for a particular approach. For example, the integrated circuit dies200may include a static random access memory (SRAM) chip or a dynamic random access memory (DRAM) chip, a processor, a memory chip, logic chip, analog chip, digital chip, a central processing unit (CPU), a graphics processing unit (GPU), a baseband processor, a microcontroller unit (MCU), a radio frequency (RF) chip, a sensor chip, a micro-electro-mechanical-system (MEMS) chip, an integrated passive device (IPD), or a combination thereof, or the like. Before being attached to the buffer layer102, the integrated circuit dies200may be processed according to applicable manufacturing processes to form integrated circuits above the integrated circuit die200. Each of dies200may include a substrate (a silicon substrate, for example) that is coupled to an adhesive layer, wherein the back surface of semiconductor substrate is coupled to the adhesive layer.

In some exemplary embodiments, the dies200include contacts202(such as copper posts) that are electrically coupled to devices such as transistors in dies200. In some embodiments, a dielectric layer (not shown) is formed at the top surface of the respective die200, with contacts202having at least lower portions in the dielectric layer. The top surfaces of the contacts202may also be level with the top surfaces of the dielectric layer in some embodiments. Alternatively, contacts202may protrude above and/or submerge below a top layer of the respective dies200. In other embodiments, other structures may be used for the contacts202, such as traces, metal pillars, copper stud, gold stud or the like.

Referring toFIG.3, molding material300is molded and/or laminated on dies200. Molding material300fills the gaps between dies200and may be in contact with buffer layer102. Furthermore, molding material300is filled into the gaps between contacts202when portions of contacts202are protruding. Molding material300may include a molding compound, a molding underfill, an epoxy, a resin, a dry film or the like. In some embodiments, the top surface of molding material300is higher than the top ends of contacts202.

A grinding step may be performed to thin molding material300to expose contacts202. The resulting structure is shown inFIG.3. Due to the grinding, the top ends of contacts202may be substantially level (coplanar) with the top surface of molding material300. As a result of the grinding, metal residues such as metal particles may be generated, and left on the top surfaces of the molding material300and contacts202. Accordingly, after the grinding, a cleaning may be performed, for example, through a wet etching, so that the metal residue is removed.

Next, referring toFIG.4, one or more redistribution layers (RDLs)400are formed. Generally, RDLs provide a conductive pattern that allows a pin-out contact pattern for a completed package different than the pattern of the metal pillars, allowing for greater flexibility in the placement of dies200. The RDLs may be utilized to provide an external electrical connection to dies200. The RDLs comprise conductive lines402and vias404, wherein vias404connect an overlying line to an underlying conductive feature (e.g., contacts202and/or conductive lines402). The conductive lines402may extend along any direction, for example, to the left or right of the page or in to or out of the page.

The RDLs may be formed using any suitable process. For example, in some embodiments, a dielectric layer is formed on the molding material300and integrated circuit dies200. In some embodiments, the dielectric layer is formed of a polymer, which may be a photo-sensitive material such as polybenzoxazole (PBO), polyimide, benzocyclobutene (BCB), or the like, that may be patterned using lithography. In other embodiments, the dielectric layer is formed of a nitride such as silicon nitride, an oxide such as silicon oxide, PhosphoSilicate Glass (PSG), BoroSilicate Glass (BSG), Boron-doped PhosphoSilicate Glass (BPSG), or the like. The dielectric layer may be formed by spin coating, lamination, CVD, the like, or a combination thereof. The dielectric layer is then patterned to form openings to expose contacts202. In embodiments in which the dielectric layer is formed of a photo-sensitive material, the patterning may be performed by exposing the dielectric layer in accordance with a desired pattern and developed to remove the unwanted material, thereby exposing contacts202. Other methods, such as using a patterned mask and etching, may also be used to pattern the dielectric layer.

A seed layer (not shown) is formed over the dielectric layer and in the openings formed in the dielectric layer. In some embodiments, the seed layer is a metal layer, which may be a single layer or a composite layer comprising a plurality of sub-layers formed of different materials. In some embodiments, the seed layer comprises a titanium layer and a copper layer over the titanium layer. The seed layer may be formed using, for example, PVD, or the like. A mask is then formed and patterned on the seed layer in accordance with a desired redistribution pattern, such as the pattern illustrated inFIG.4. In some embodiments, the mask is a photoresist formed by spin coating or the like and exposed to light for patterning. The patterning forms openings through the mask to expose the seed layer. A conductive material is formed in the openings of the mask and on the exposed portions of the seed layer. The conductive material may be formed by plating, such as electroplating or electroless plating, or the like. The conductive material may comprise a metal, like copper, titanium, tungsten, aluminum, or the like. Then, the photoresist and portions of the seed layer on which the conductive material is not formed, are removed. The photoresist may be removed by an acceptable ashing or stripping process, such as using an oxygen plasma or the like. Once the photoresist is removed, exposed portions of the seed layer are removed, such as by using an acceptable etching process, such as by wet or dry etching. The remaining portions of the seed layer and conductive material form the conductive lines402and vias404.

While the formation of one layer of RDL is described above, the process may be repeated to create more than one layer of RDLs, depending on the design of the particular approach. For example, one layer of RDLs is depicted inFIG.4. More layers of RDLs are possible.

Next, a passivation layer406may be formed over an uppermost metallization pattern in accordance with some embodiments. The passivation layer may be formed of a polymer, which may be a photo-sensitive material such as PBO, polyimide, BCB, or the like, that may be patterned using a lithography mask. In other embodiments, the passivation layer is formed of a nitride or an oxide such as silicon nitride, silicon oxide, PSG, BSG, BPSG, or the like. The passivation layer may be formed by spin coating, lamination, CVD, the like, or a combination thereof. The passivation layer is then patterned to expose portions of the underlying metallization layer. The patterning may be by an acceptable process, such as by exposing the passivation layer to light when the dielectric layer is a photo-sensitive material or by etching using, for example, an anisotropic etch. Next, an under bump metallization (UBM)408is formed and patterned over and through the passivation layer, thereby forming an electrical connection with an uppermost metallization layer. The under bump metallization provides an electrical connection upon which an electrical connector, e.g., a solder ball/bump, a conductive pillar, or the like, may be placed. In some embodiments, the under bump metallization includes a diffusion barrier layer, a seed layer, or a combination thereof. The diffusion barrier layer may include Ti, TiN, Ta, TaN, or combinations thereof. The seed layer may include copper or copper alloys. However, other metals, such as nickel, palladium, silver, gold, aluminum, combinations thereof, and multi-layers thereof, may also be included. In some embodiments, under bump metallization is formed using sputtering. In other embodiments, electro plating may be used.

Connectors410may be formed over the under bump metallization in accordance with some embodiments. The connectors410may be solder balls, metal pillars, controlled collapse chip connection (C4) bumps, micro bumps, electroless nickel-electroless palladium-immersion gold technique (ENEPIG) formed bumps, combination thereof (e.g., a metal pillar having a solder ball attached thereof), or the like. The connectors410may include a conductive material such as solder, copper, aluminum, gold, nickel, silver, palladium, tin, the like, or a combination thereof. In some embodiments, the connectors410comprise a eutectic material and may comprise a solder bump or a solder ball, as examples. The solder material may be, for example, lead-based and lead-free solders, such as Pb—Sn compositions for lead-based solder; lead-free solders including InSb; tin, silver, and copper (SAC) compositions; and other eutectic materials that have a common melting point and form conductive solder connections in electrical applications. For lead-free solder, SAC solders of varying compositions may be used, such as SAC105(Sn 98.5%, Ag 1.0%, Cu 0.5%), SAC305, and SAC405, as examples. Lead-free connectors such as solder balls may be formed from SnCu compounds as well, without the use of silver (Ag). Alternatively, lead-free solder connectors may include tin and silver, Sn—Ag, without the use of copper. The connectors410may form a grid, such as a ball grid array (BGA). In some embodiments, a reflow process may be performed, giving the connectors410a shape of a partial sphere in some embodiments. Alternatively, the connectors410may comprise other shapes. The connectors410may also comprise non-spherical conductive connectors, for example.

In some embodiments, the connectors410comprise metal pillars (such as a copper pillar) formed by a sputtering, printing, electro plating, electroless plating, CVD, or the like, with or without a solder material thereon. The metal pillars may be solder free and have substantially vertical sidewalls or tapered sidewalls.

Next, carrier substrate100is de-bonded from buffer layer102, as illustrated inFIG.5. If present, the release layer is also cleaned from the buffer layer102. For example, in the case of an epoxy-based thermal release material, which loses its adhesive property when heated, the structure is heated and the carrier substrate100is debonded. As another example, in the case of an ultra-violet (UV) glue release layer, the release layer is exposed to UV light and the carrier is debonded. As another example, the release layer may be dispensed as a liquid and cured. Optionally, buffer layer102may also be removed from the structure.

FIG.6illustrates the bonding of components600and packages602to the structure on the opposite side of the RDLs400from the dies200. In some embodiments, depending on the total thickness of molding material300and RDLs400, warpage of the structure may be an issue. If warpage is a concern, then the carrier substrate100may be needed to support the structure during the bonding of components600and packages602to the structure. In this case, carrier substrate is 100 debonded after the bonding of components600and packages602to the structure, instead of before.

In some embodiments, components600are surface mounted to the structure. Any type of surface mounted component may be used, depending on the design and requirements of particular embodiments, and may include discrete devices, passive surface mounted components (for example resistors and capacitors) as well as active devices, for example transistors, diodes, and amplifiers. Packages602comprising one or more dies mounted on a packaging substrate and encased in a molding material may also be connected to the structure. For example, packages602may include integrated circuit dies such as a static random access memory (SRAM) chip or a dynamic random access memory (DRAM) chip, a processor, a memory chip, logic chip, analog chip, digital chip, a central processing unit (CPU), a graphics processing unit (GPU), a baseband processor, a microcontroller unit (MCU), a radio frequency (RF) chip, a sensor chip, a micro-electro-mechanical-system (MEMS) chip, or a combination thereof, or the like. In some embodiments, one or more packages602will be tested before and after being bonded to the structure. For example, micro-electro-mechanical-systems (MEMS) packages may be tested before or after being bonded to the RDLs in some embodiments. Such packages will be bonded to the package in a manner that allows access to the package for testing purposes after being bonded. In some embodiments, integrated circuit dies packaged in a wafer level chip scale package (WLCSP) may be bonded directly to the RDLs400opposite the dies200.

In some embodiments, the structure is designed in a manner that allows for electrical connections between components or packages in the structure with increased reliability. For example, depending on the design of some embodiments, a die200may be placed on one side of the RDLs opposite to a surface mounted component600or a package602on the other side of the RDLs in such a manner that there is a short connection path in the RDLs between the two devices. The short connection path increases the reliability of the electrical connection between the two devices as compared to a longer connection path. Additionally, some embodiments may be designed in a manner that eliminates the need for through vias, which are commonly used in many 3D wafer and/or panel level fan-out structures. For example, the embodiment depicted inFIG.6does not have any through vias extending through the molding material300.

Next, the structure is singulated into a plurality of InFO structures700.FIG.7illustrates a cross-sectional view of one of InFO structures700. Each singulated InFO structure700may include any number of dies200, components600, and/or packages602for a particular design. For example,FIG.7illustrates an embodiment that includes two dies200, one component600, and one package602. Other embodiments may have more or fewer of each element.

Referring now toFIGS.8A and8B, in some embodiments InFO structure700is connected to a printed circuit board (PCB)800and installed in a cover806. InFO structure700inFIGS.8A and8Bdepict a different embodiment of InFO structure700thanFIG.7for purposes of illustration. Either embodiment, or other embodiments, is possible. InFO structure700and PCB800, as connected, are jointly referred to herein as integrated circuit structure804.FIG.8Adepicts a cross sectional view of integrated circuit structure804, whileFIG.8Bdepicts a plan view of integrated circuit structure804.

PCB800provides increased mechanical strength to integrated circuit structure804. PCB800may be mechanically stronger than InFO structure700, and therefore may provide increased structural support to integrated circuit structure804. The increased mechanical strength of PCB800may be used for mounting or connecting to larger devices, which may help to increase reliability of the integrated circuit structure804. Also, the increased mechanical structural support of PCB800may enable a more secure mechanical installation of the integrated circuit structure804in a product than would otherwise be possible. For example, PCB800may allow the integrated circuit structure804to be installed in a product using a through hole device, for example a screw.

In some embodiments, integrated circuit structure804may be designed in such a manner that larger components with limited I/O requirements, such as batteries and antennas, will be mounted on, or connected to, PCB800. InFO structure700has a lower mechanical strength, and can support increased I/O connections in a smaller area, as compared to PCB800. As such, some embodiments of integrated circuit structure804may be designed so that larger components with minimal I/O requirements are mounted on, or mechanically connected to, PCB800instead of InFO structure700. The larger components may then be electrically connected to InFO structure700using connective traces in PCB800(e.g. traces810,812). Such a design may preserve space on InFO structure700for smaller components with high I/O requirements, which is supported by RDLs400, and enable increased miniaturization of integrated circuit structure804, which may be desirable for some applications. For example,FIGS.8A and8Billustrate an embodiment having an antenna808and power connector802mounted on the PCB800.

In some embodiments, InFO structure700is connected to PCB800at one end of the InFO structure700as depicted inFIGS.8A and8B. The connection between PCB800and InFO structure700may be on the same surface of RDLs400as the surface mounted components600and packages602. Power connector802provides an electrical connection to a battery (not shown) to integrated circuit structure804. Power connector802and antenna808are connected to InFO structure700by conductive traces in PCB800. In some embodiments, as shown inFIG.9B, trace810connects a terminal of a battery to InFO structure700and trace812connects the other terminal of a battery to InFO structure700.

In some embodiments, PCB800is connected to InFO structure700using soldering. InFO structure700may extend a distance A of 20 μm to 2000 μm past the inner cavity edge of PCB800. As described above, the solder material may be, for example, lead-based and lead-free solders, such as Pb—Sn compositions for lead-based solder; lead-free solders including InSb; tin, silver, and copper (SAC) compositions; and other eutectic materials that have a common melting point and form conductive solder connections in electrical applications. For lead-free solder, SAC solders of varying compositions may be used, such as SAC105(Sn 98.5%, Ag 1.0%, Cu 0.5%), SAC305, and SAC405, as examples. Lead-free connectors such as solder balls may be formed from SnCu compounds as well, without the use of silver (Ag). Alternatively, lead-free solder connectors may include tin and silver, Sn—Ag, without the use of copper. In some embodiments, a reflow process may be performed, giving the connectors a shape of a partial sphere in some embodiments. Alternatively, the connectors may comprise other shapes. The connectors may also comprise non-spherical conductive connectors, for example. In some embodiments, the InFO structure700may be attached to the PCB800using an adhesive (not shown) to provide additional support.

Integrated circuit structure804is installed in cover806. In some embodiments, integrated circuit structure804and cover806form a standalone product that is configured to connect to the internet. As shown inFIG.8A, InFO structure700is supported on two ends, on one end by PCB800and on a second end by cover806. Integrated circuit structure804may be secured in cover806by soldering a layer of RDLs400to contact pad814using methods described earlier. In some embodiments, an adhesive may be used to connect the Info structure700to the cover806. InFO structure700may extend a distance B of 500 μm to 2000 μm past the edge of cover806.

Referring toFIGS.9A and9B, a cross sectional view and a plan view of integrated circuit structure804, including an InFO structure, such as InFO structure700, connected to PCB800, is provided. Instead of mounting InFO structure700to PCB800on one side of InFO structure700, as depicted inFIGS.8A and8B,FIGS.9A and9Billustrates an embodiment where InFO structure700is mounted to PCB800on all four sides of InFO structure700by placing InFO structure700in an opening in PCB800. This embodiment may provide more robust mechanical support to InFO structure700. InFO structure700inFIGS.9A and9Bdepict a different embodiment of InFO structure700thanFIGS.7,8A and8B, for example in the number and placement of dies and packages, for purposes of illustration. Any of these embodiments, or other embodiments, is possible.

In some embodiments, as depicted inFIGS.9A and9B, InFO structure700is arranged in an opening in PCB800. Power connector802is connected to PCB800. Power connector802may be used to connect integrated circuit structure804to a battery (not shown). An antenna808is also mounted on PCB800. Conductive lines in PCB800connect the power connector802and antenna808to InFO structure700. In some embodiments, as shown inFIG.9B, trace810connects one terminal of a battery to one side of InFO structure700and trace812connects the other terminal of a battery to a second side of InFO structure700.

Mechanical installation devices900may be used for installing integrated circuit structure804in cover806. For example, mechanical installation device may be a through hole device, such as a screw. Other suitable mechanical installation devices may be used, depending on the approach and the requirements of the product in which the integrated circuit device is being installed.

In some embodiments, integrated circuit structure804and cover806comprise a standalone structure that is installed in a product. The InFO technology of InFO structure700allows for miniaturization of the integrated circuit structure804, while PCB800provides mechanical structural support and a secure connection for larger connectors and devices, while saving space on InFO structure700for components and packages with higher I/O requirements. In some embodiments, the integrated circuit structure804is configured to connect to the internet. Some embodiments of the integrated circuit structure804may be suitable for Internet of Things (IoT) devices, as some embodiments of the integrated circuit device may be miniaturized standalone devices that are configured to connect to the internet. As an example, some embodiments of integrated circuit structure804may be configured to be compliant with one or more standards promulgated by the ZigBee Alliance.

Although embodiments have been described herein with respect to embodiments comprising a standalone three dimensional InFO and PCB structure installed in a cover and suitable for use, for example, with home appliances, other embodiments may be suitable for other applications. For example, some embodiments may be suitable for medical devices, home automation, geographic location services, mobile communications, and marketing applications. Many different embodiments and applications are possible.

Embodiments of the invention provide a method of making a semiconductor device. The method includes placing a die over a carrier substrate and forming a molding compound adjacent to the die. A redistribution layer is formed, electrically coupled to the die and overlying the molding compound. The carrier substrate is removed. A first substrate is connected to the redistribution layer on an opposite side of the redistribution layer from the die, and the redistribution layer is connected to a printed circuit board.

Embodiments of the invention provide a method of making a semiconductor device. The method includes placing a plurality of dies over a carrier substrate. A molding compound is formed along sidewalls of the dies, wherein the molding compound absent a through via extending through the molding compound. A redistribution layer is formed, electrically coupled to the dies and overlying the molding compound. The carrier substrate is removed. One or more devices, passives components, and/or packages are placed on the redistribution layer.

Embodiments of the present invention provide a semiconductor device. The semiconductor device includes a die and molding compound extending along sidewalls of the die. A redistribution layer overlies the molding compound and the die. A substrate is mounted to the redistribution layer on an opposite side of the redistribution layer from the molding compound. A printed circuit board is connected to the redistribution layer.

While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments.