Editing Semiconductor device fabrication (section)

==Packaging==
{{Main|Integrated circuit packaging}}

After the dies are tested for functionality and binned, they are packaged. Plastic or ceramic packaging involves mounting the die, connecting the die/bond pads to the pins on the package, and sealing the die. Tiny [[Wire bonding|bondwires]] are used to connect the pads to the pins. In the 'old days' (1970s), wires were attached by hand, but now specialized machines perform the task. Traditionally, these wires have been composed of gold, leading to a [[lead frame]] (pronounced "leed frame") of [[solder]]-plated copper; [[lead]] is poisonous, so lead-free "lead frames" are now mandated by [[Restriction of Hazardous Substances Directive|RoHS]]. Traditionally the bond pads are located on the edges of the die, however, [[Flip-chip]] packaging can be used to place bond pads across the entire surface of the die.

[[Chip scale package]] (CSP) is another packaging technology. A plastic [[dual in-line package]], like most packages, is many times larger than the actual die hidden inside, whereas CSP chips are nearly the size of the die; a CSP can be constructed for each die ''before'' the wafer is diced.

The packaged chips are retested to ensure that they were not damaged during packaging and that the die-to-pin interconnect operation was performed correctly. A laser then etches the chip's name and numbers on the package. The steps involving testing and packaging of dies, followed by final testing of finished, packaged chips, are called the back end,<ref name="stmicro-an900" /> post-fab,<ref>{{cite web | url=https://www.3dincites.com/2009/04/the-post-fab-process-debate-for-3d-ics-foundry-or-osats/ | title=The post-fab process debate for 3D ICs: Foundry or OSATS | date=30 April 2009 }}</ref> ATMP (Assembly, Test, Marking, and Packaging)<ref>{{cite web | url=https://www.electronicsb2b.com/industry-buzz/invest/atmps-founding-stone-indias-semiconductor-era/ | title=ATMPs: The Founding Stone of India's Semiconductor Era | date=19 January 2022 }}</ref> or ATP (Assembly, Test and Packaging) of semiconductor manufacturing, and may be carried out by OSAT (OutSourced Assembly and Test) companies which are separate from semiconductor foundries. A foundry is a company or fab performing manufacturing processes such as photolithography and etching that are part of the front end of semiconductor manufacturing.<ref>{{cite web | url=https://www.semiconductors.org/ecosystem/ | title=U.S. Semiconductor Ecosystem Map | date=20 March 2023 }}</ref>