Pure-play Semiconductor Foundry

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. It was first conceived by Morris Chang, the founder of the Taiwan Semiconductor Manufacturing Company Limited (TSMC).

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.

History

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 founded by Morris Chang, a spin-off of the government Industrial Technology Research Institute, which split its design and fabrication divisions in 1987, 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.

Fabless semiconductor companies do not have any semiconductor fabrication capability, instead contracting with a merchant foundry for fabrication. 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. Many 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 model that seeks to optimize productivity.

MOSIS

The very first merchant foundries were part of the MOSIS service. The MOSIS service gave limited production access to designers with limited means, such as students, university researchers, and engineers at small startups. The designer submitted designs, and these submissions were manufactured with the commercial company's extra capacity. Manufacturers could insert some wafers for a MOSIS design into a collection of their own wafers when a processing step was compatible with both operations. The commercial company (serving as foundry) was already running the process, so they were effectively being paid by MOSIS for something they were already doing. A factory with excess capacity during slow periods could also run MOSIS designs to avoid having expensive capital equipment stand idle.

Under-use of an expensive manufacturing plant could lead to the financial ruin of the owner, so selling surplus wafer capacity was a way to maximize the fab's use. Hence, economic factors created a climate where fab operators wanted to sell surplus wafer-manufacturing capacity and designers wanted to purchase manufacturing capacity rather than try to build it.

Although MOSIS opened the doors to some fabless customers, earning additional revenue for the foundry and providing inexpensive service to the customer, running a business around MOSIS production was difficult. The merchant foundries sold wafer capacity on a surplus basis, as a secondary business activity. Services to the customers were secondary to the commercial business, with little guarantee of support. The choice of merchant dictated the design, development flow, and available techniques to the fabless customer. Merchant foundries might require proprietary