The foundry model is a microelectronics engineering and manufacturing business model consisting of a semiconductor fabrication plant, or foundry, and an integrated circuit design operation, each belonging to separate companies or subsidiaries.^[1][2][3][4]

Integrated device manufacturers (IDMs) design and manufacture integrated circuits. Many companies, known as fabless semiconductor companies, only design devices; merchant or pure play foundries only manufacture devices for other companies, without designing them. Examples of IDMs are Intel, Samsung, and Texas Instruments, examples of pure play foundries are GlobalFoundries, TSMC, and UMC, and examples of fabless companies are AMD, Nvidia, and Qualcomm.

Integrated circuit production facilities are expensive to build and maintain. Unless they can be kept at nearly full use, they will become a drain on the finances of the company that owns them. The foundry model uses two methods to avoid these costs: fabless companies avoid costs by not owning such facilities. Merchant foundries, on the other hand, find work from the worldwide pool of fabless companies, through careful scheduling, pricing, and contracting, keep their plants in full use.

Companies that both designed and produced the devices were originally responsible for manufacturing microelectronic devices. These manufacturers were involved in both the research and development of manufacturing processes and the research and development of microcircuit design.

The first pure play semiconductor company is the Taiwan Semiconductor Manufacturing Corporation, a spin-off of the government Industrial Technology Research Institute, which split its design and fabrication divisions in 1987,^[5] a model advocated for by Carver Mead in the U.S., but deemed too costly to pursue. The separation of design and fabrication became known as the foundry model, with fabless manufacturing outsourcing to semiconductor foundries.^[6]

Fabless semiconductor companies do not have any semiconductor fabrication capability; and contract production with a merchant foundry manufacturer. The fabless company concentrates on the research and development of an IC-product; the foundry concentrates on manufacturing and testing the physical product. If the foundry does not have any semiconductor design capability, it is a pure-play semiconductor foundry.

An absolute separation into fabless and foundry companies is not necessary. Some companies continue to exist that perform both operations and benefit from the close coupling of their skills. Some companies manufacture some of their own designs and contract out to have others manufactured or designed, in cases where they see value or seek special skills. The foundry model is a business vision that seeks to optimize productivity.

• Pure-play semiconductor foundry is a company that does not offer a significant amount of IC products of its own design, but instead operates semiconductor fabrication plants focused on producing ICs for other companies.^[9]
• Integrated device manufacturer (IDM) semiconductor foundry is where companies such as Texas Instruments, IBM, and Samsung join in to provide foundry services as long as there is no conflict of interest between relevant parties.

Like all industries, the semiconductor industry faces upcoming challenges and obstacles.

The cost to stay on the leading edge has steadily increased with each generation of chips. The financial strain is being felt by both large merchant foundries and their fabless customers. The cost of a new foundry exceeds $1 billion. These costs must be passed on to customers. Many merchant foundries have entered into joint ventures with their competitors in an effort to split research and design expenditures and fab-maintenance expenses.

Chip design companies sometimes avoid other companies' patents simply by purchasing the products from a licensed foundry with broad cross-license agreements with the patent owner.^[24]

Stolen design data is also a concern; data is rarely directly copied, because blatant copies are easily identified by distinctive features in the chip,^[25] placed there either for this purpose or as a byproduct of the design process. However, the data including any procedure, process system, method of operation or concept may be sold to a competitor, who may save months or years of tedious reverse engineering.