Fan-out wafer-level packaging (also known as wafer-level fan-out packaging, fan-out WLP, FOWL packaging, FO-WLP, FOWLP, etc.) is an integrated circuit packaging technology, and an enhancement of standard wafer-level packaging (WLP) solutions. [1] [2] Fan-out packaging is seen as a low cost advanced packaging alternative to packages that use silicon interposers, such as those seen in 2.5D and 3D packages. [3] [4]
In conventional technologies, a wafer is diced first, and then individual dies are packaged; package size is usually considerably larger than the die size. By contrast, in standard WLP flows integrated circuits are packaged while still part of the wafer, and the wafer (with outer layers of packaging already attached) is diced afterwards; the resulting package is practically of the same size as the die itself. However, the advantage of having a small package comes with a downside of limiting the number of external contacts that can be accommodated in the limited package footprint; this may become a significant limitation when complex semiconductor devices requiring a large number of contacts are considered. [5]
Fan-out WLP was developed to relax that limitation. It provides a smaller package footprint along with improved thermal and electrical performance compared to conventional packages, and allows having higher number of contacts without increasing the die size.
In contrast to standard WLP flows, in fan-out WLP the wafer is diced first. But then the dies are very precisely re-positioned on a carrier wafer or panel, with space for fan-out kept around each die. The carrier is then reconstituted by molding, followed by making a redistribution layer atop the entire molded area (both atop the chip and atop the adjacent fan-out area), and then forming solder balls on top and dicing the wafer. This is known as a chip-first flow. Panel level packaging uses a large panel instead of a wafer to carry out the packaging process. [6] High end fan-out packages are those with lines and spaces narrower than 8 microns. [4] Fan-out packages can also have several dies, [5] and passive components. [6] The first fan-out packages were developed by Infineon in the mid-2000s for use in mobile phone chips. [5]
An integrated circuit (IC), also known as a microchip, computer chip, or simply chip, is a small electronic device made up of multiple interconnected electronic components such as transistors, resistors, and capacitors. These components are etched onto a small piece of semiconductor material, usually silicon. Integrated circuits are used in a wide range of electronic devices, including computers, smartphones, and televisions, to perform various functions such as processing and storing information. They have greatly impacted the field of electronics by enabling device miniaturization and enhanced functionality.
Semiconductor device fabrication is the process used to manufacture semiconductor devices, typically integrated circuits (ICs) such as computer processors, microcontrollers, and memory chips. It is a multiple-step photolithographic and physico-chemical process during which electronic circuits are gradually created on a wafer, typically made of pure single-crystal semiconducting material. Silicon is almost always used, but various compound semiconductors are used for specialized applications.
A semiconductor device is an electronic component that relies on the electronic properties of a semiconductor material for its function. Its conductivity lies between conductors and insulators. Semiconductor devices have replaced vacuum tubes in most applications. They conduct electric current in the solid state, rather than as free electrons across a vacuum or as free electrons and ions through an ionized gas.
In electronics, a wafer is a thin slice of semiconductor, such as a crystalline silicon, used for the fabrication of integrated circuits and, in photovoltaics, to manufacture solar cells.
Flip chip, also known as controlled collapse chip connection or its abbreviation, C4, is a method for interconnecting dies such as semiconductor devices, IC chips, integrated passive devices and microelectromechanical systems (MEMS), to external circuitry with solder bumps that have been deposited onto the chip pads. The technique was developed by General Electric's Light Military Electronics Department, Utica, New York. The solder bumps are deposited on the chip pads on the top side of the wafer during the final wafer processing step. In order to mount the chip to external circuitry, it is flipped over so that its top side faces down, and aligned so that its pads align with matching pads on the external circuit, and then the solder is reflowed to complete the interconnect. This is in contrast to wire bonding, in which the chip is mounted upright and fine wires are welded onto the chip pads and lead frame contacts to interconnect the chip pads to external circuitry.
Integrated circuit packaging is the final stage of semiconductor device fabrication, in which the die is encapsulated in a supporting case that prevents physical damage and corrosion. The case, known as a "package", supports the electrical contacts which connect the device to a circuit board.
A chip scale package or chip-scale package (CSP) is a type of integrated circuit package.
A system in a package (SiP) or system-in-package is a number of integrated circuits (ICs) enclosed in one chip carrier package or encompassing an IC package substrate that may include passive components and perform the functions of an entire system. The ICs may be stacked using package on package, placed side by side, and/or embedded in the substrate. The SiP performs all or most of the functions of an electronic system, and is typically used when designing components for mobile phones, digital music players, etc. Dies containing integrated circuits may be stacked vertically on the package substrate. They are internally connected by fine wires that are bonded to the package substrate. Alternatively, with a flip chip technology, solder bumps are used to join stacked chips together and to the package substrate, or even both techniques can be used in a single package. SiPs are like systems on a chip (SoCs) but less tightly integrated and not on a single semiconductor die.
Lam Research Corporation is an American supplier of wafer-fabrication equipment and related services to the semiconductor industry. Its products are used primarily in front-end wafer processing, which involves the steps that create the active components of semiconductor devices and their wiring (interconnects). The company also builds equipment for back-end wafer-level packaging (WLP) and for related manufacturing markets such as for microelectromechanical systems (MEMS).
Die singulation, also called wafer dicing, is the process in semiconductor device fabrication by which dies are separated from a finished wafer of semiconductor. Die singulation comes after the photolithography process. It can involve scribing and breaking, mechanical sawing or laser cutting. All methods are typically automated to ensure precision and accuracy. Following the dicing process the individual silicon chips may be encapsulated into chip carriers which are then suitable for use in building electronic devices such as computers, etc.
Package on a package (PoP) is an integrated circuit packaging method to vertically combine discrete logic and memory ball grid array (BGA) packages. Two or more packages are installed atop each other, i.e. stacked, with a standard interface to route signals between them. This allows higher component density in devices, such as mobile phones, personal digital assistants (PDA), and digital cameras, at the cost of slightly higher height requirements. Stacks with more than 2 packages are uncommon, due to heat dissipation considerations.
In electronic engineering, a through-silicon via (TSV) or through-chip via is a vertical electrical connection (via) that passes completely through a silicon wafer or die. TSVs are high-performance interconnect techniques used as an alternative to wire-bond and flip chips to create 3D packages and 3D integrated circuits. Compared to alternatives such as package-on-package, the interconnect and device density is substantially higher, and the length of the connections becomes shorter.
A three-dimensional integrated circuit is a MOS integrated circuit (IC) manufactured by stacking as many as 16 or more ICs and interconnecting them vertically using, for instance, through-silicon vias (TSVs) or Cu-Cu connections, so that they behave as a single device to achieve performance improvements at reduced power and smaller footprint than conventional two dimensional processes. The 3D IC is one of several 3D integration schemes that exploit the z-direction to achieve electrical performance benefits in microelectronics and nanoelectronics.
Wafer-level packaging (WLP) is a process in integrated circuit manufacturing where packaging components are attached to an integrated circuit (IC) before the wafer – on which the IC is fabricated – is diced. In WLP, the top and bottom layers of the packaging and the solder bumps are attached to the integrated circuits while they are still in the wafer. This process differs from a conventional process, in which the wafer is sliced into individual circuits (dice) before the packaging components are attached.
Embedded wafer level ball grid array (eWLB) is a packaging technology for integrated circuits. The package interconnects are applied on an artificial wafer made of silicon chips and a casting compound.
A redistribution layer (RDL) is an extra metal layer on an integrated circuit that makes its I/O pads available in other locations of the chip, for better access to the pads where necessary.
Advanced Semiconductor Engineering, Inc., previously known as ASE Group, is a leading provider of independent semiconductor packaging and test manufacturing services, with its headquarters in Kaohsiung, Taiwan.
Glossary of microelectronics manufacturing terms
Advanced packaging is the aggregation and interconnection of components before traditional integrated circuit packaging where a single die is packaged. Advanced packaging allows multiple devices, including electrical, mechanical, or semiconductor devices, to be merged and packaged as a single electronic device. Advanced packaging uses processes and techniques that are typically performed at semiconductor fabrication facilities, unlike traditional integrated circuit packaging, which does not. Advanced packaging thus sits between fabrication and traditional packaging -- or, in other terminology, between BEoL and post-fab. Advanced packaging includes multi-chip modules, 3D ICs, 2.5D ICs, heterogeneous integration, fan-out wafer-level packaging, system-in-package, quilt packaging, combining logic (processors) and memory in a single package, die stacking, wafer bonding/stacking, several chiplets or dies in a package, combinations of these techniques, and others. 2.5D and 3D ICs are also called 2.5D or 3D packages.