Full custom

Inintegrated circuit design,full-customis a design methodology in which the layout of each individualtransistoron theintegrated circuit(IC), and the interconnections between them, are specified. Alternatives to full-custom design include various forms of semi-custom design, such as the repetition of small transistor subcircuits;one such methodology is the use ofstandard cell libraries(which are themselves designed full-custom).

Full-custom design potentially maximizes theperformanceof the chip, and minimizes its area, but is extremely labor-intensive to implement. Full-custom design is limited to ICs that are to be fabricated in extremely high volumes, notably certainmicroprocessorsand a small number ofapplication-specific integrated circuits(ASICs).

As of 2008 the main factor affecting the design and production of ASICs was the high cost ofmask sets(number of which is depending on the number of IC layers) and the requisiteEDAdesign tools. The mask sets are required in order to transfer the ASIC designs onto thewafer.

See also

• Electronics design flow