Today, UMC is best known for its merchant foundry business, manufacturing integrated circuitswafers for fabless semiconductor companies. In this role, UMC is second only to competitor TSMC. It has two 300 mm fabs, one in Taiwan and one in Singapore.
UMC was the first foundry to produce chips on 300 mm wafers, ship wafers using copper materials, to sell 65 nm IC's to customers, and to produce chips using 28 nm process technology. It was the first Taiwanese company to offer foundry services and the first semiconductor company to be listed on the Taiwan Stock Exchange in 1985.