HSINCHU, Taiwan, August 22, 2005 - UMC (NYSE: UMC; TSE: 2303), a world leading semiconductor foundry, today announced that it has reached a significant production milestone with the shipment of over 100,000 customer wafers¹ for products using 90-nanometer (nm) process technology.

UMC has been leading all foundries in total 90nm wafers shipped as well as overall revenue generated from 90nm sales. Moreover, 90nm customer products being manufactured at UMC encompass a broad range of market sectors, including leading-edge wireless and wired communications, high-end consumer, and advanced computing. This achievement of wafer shipments from such a diverse range of applications underscores the production maturity and readiness of UMC's 90nm process for every major advanced application.

Lee Chung, vice president of the Corporate Marketing division at UMC, commented, "Surpassing 100,000 wafer shipments is a significant milestone for 90nm. Two years ago, UMC recognized the need to transform itself from a traditional foundry that focused on process development and manufacturing into a foundry that offered SOC solutions to customers. This transformation has accomplished its initial goals and customers are starting to reap the benefits.

Mr. Chung continued, "Within the industry, at least two companies have announced that they will have single chip GSM products that integrate the baseband and RF transceiver. We have also seen WLAN 802.11 a/b/g and Bluetooth products that integrate baseband and RF, a development that the design community has been anticipating for many years. It will be exciting to watch these 90nm enabled products proliferate into the mainstream."

In July 2005 alone, UMC shipped over 10,000 90nm wafers. Monthly shipment levels are expected to double this amount by Q4 2005, due to strong demand. UMC's 90nm production is taking place at both of its 300mm fabs and one 200mm fab, with over 20 different products now being manufactured. The majority of the products being manufactured take advantage of UMC's low-k dielectrics. In addition to UMC's standard 90nm device offering, customers are also utilizing either the company's 90nm low-power or high-speed device options, depending upon their product application. Several customer products have reached mature yield levels, allowing them to realize the full advantage of this advanced technology. Many more products are in various stages of development, including several 90nm RF designs that have already been silicon verified.

In March 2003, UMC became the world's first foundry to deliver working 90nm customer products. By the end of Q2 2005, revenue from UMC's 90nm process reached 9% of total revenue. The company expects this figure to grow to 15% by the end of Q3 2005.

1. 8-inch wafer equivalents. One 12-inch wafer is converted into 2.25 (12²/8²) 8-inch equivalent

UMC (NYSE: UMC, TSE: 2303) is a leading global semiconductor foundry that manufactures advanced process ICs for applications spanning every major sector of the semiconductor industry. UMC delivers cutting-edge foundry technologies that enable sophisticated system-on-chip (SoC) designs, including 90nm copper, 0.13um copper, and mixed signal/RFCMOS. UMC is also a leader in 300mm manufacturing; Fab 12A in Taiwan and Singapore-based Fab 12i are both in volume production for a variety of customer products. UMC employs approximately 10,500 people worldwide and has offices in Taiwan, Japan, Singapore, Europe, and the United States. UMC can be found on the web at http://www.umc.com.

Some of the statements in the foregoing announcement are forward looking within the meaning of the U.S. Federal Securities laws, including statements about future outsourcing, wafer capacity, technologies, business relationships and market conditions. Investors are cautioned that actual events and results could differ materially from these statements as a result of a variety of factors, including conditions in the overall semiconductor market and economy; acceptance and demand for products from UMC; and technological and development risks.