What Does a Semiconductor Foundry Do?

A semiconductor foundry manufactures chips for other companies, turning a circuit design into physical electronic devices. Its central job is to make the tiny structures and connections that allow a chip to work, then repeat that process reliably across many wafers. Some foundry services also include help with design, packaging and testing. The distinction matters because the company whose name appears on a processor does not necessarily own the factory that fabricated it.

Chip design and chip manufacturing solve different problems. Designers decide what a device should do and develop the circuitry needed to achieve it. A foundry supplies a manufacturing process that can turn that circuitry into silicon. TSMC describes its dedicated foundry business as manufacturing customers’ products, rather than selling competing chip designs of its own. Companies that focus on design while contracting out fabrication are often called fabless. Other businesses combine chip design with their own manufacturing operations, so the industry has several ways of dividing the work.

The connection between a design and a factory begins before production. Foundries provide process design kits, usually shortened to PDKs. These contain models, rules and libraries that describe a particular manufacturing technology to electronic design software. GlobalFoundries explains that its kits include checks for design rules, circuit consistency and reliability. Such tools help engineers design something the chosen process can actually build. A useful comparison is an architect working with the capabilities and construction rules of a particular building system: an attractive drawing alone is not enough.

Inside a fabrication plant, or fab, production starts with a smooth semiconductor wafer, commonly silicon. Thin material layers are deposited on it. A light-sensitive coating called photoresist is patterned using lithography, in which light transfers a carefully controlled image onto the coating. Further processing removes selected material or adds new structures. Etching and other operations gradually create the features required by the circuit. The finished chip is therefore built through a sequence of material changes, rather than carved out in a single operation or printed in one quick pass.

Those operations are repeated to build layers of interconnected patterns. Keeping the layers aligned is essential, as is controlling contamination. ASML describes fabs in which air quality and temperature are tightly managed and robots move wafers between machines. A stray particle can damage a tiny structure, which is why cleanrooms and protective clothing are part of the manufacturing system. The wafer also carries repeated chip patterns: producing many devices together is different from assembling one complete processor by hand and then starting the next.

Fabrication is only part of the journey to a usable component. After wafer processing, individual chips are separated, assembled into packages and tested. Texas Instruments describes this as back-end manufacturing. The package helps turn the small piece of semiconductor into a component that can be incorporated into an electronic product. Testing checks that the resulting devices meet the relevant requirements. The Semiconductor Industry Association distinguishes this assembly, test and packaging stage from front-end wafer fabrication; both are needed before finished chips are ready for circuit-board assembly.

Modern foundry offerings can extend beyond making one piece of silicon. Intel Foundry describes services spanning design support, wafer fabrication, advanced packaging and testing. Its systems-of-chips approach brings multiple dies or chiplets together within a package, rather than requiring every function to reside on one die. This helps explain why discussions of foundries increasingly include packaging technology alongside manufacturing processes. Producing the separate pieces and connecting them into a functioning system are related tasks, but they are not identical tasks.

A foundry is also part of a wider network. Design tools, specialist equipment, materials, manufacturing processes and assembly services have to work together. The foundry coordinates a crucial section of that chain, while depending on other specialists for much of what goes into production. When reading about a semiconductor company, it helps to ask which activity is being discussed: designing a chip, fabricating its circuits, packaging the resulting dies or testing the finished component. Each describes a different part of how a design becomes working hardware.

Sources: TSMC: dedicated foundry model; GlobalFoundries: process design kits; ASML: chipmaking steps; ASML: inside chip manufacturing; Texas Instruments: assembly and test; Intel Foundry fact sheet; Semiconductor Industry Association: manufacturing stages.