MATTSON TECHNOLOGY INSTALLS $30 MILLION WORTH OF 300 MM EQUIPMENT AT PROMOS TECHNOLOGIES INC.

Fab's Installation Reflects Confidence in Mattson's 300 mm Expertise Across All Three Divisions

FREMONT, Calif. - September 17, 2001 - Mattson Technology (NASDAQ: MTSN), a leading supplier of advanced process equipment used to manufacture semiconductors, today announced it has begun installing $30 million worth of 300 mm equipment at ProMOS Technologies Inc. This installation spans all three of the company's divisions - Wet, Thermal and Plasma - and includes several AWP300 wet processing equipment, as well as multiple Aspen Strip and 3000 RTP systems.

ProMOS has been a Mattson customer for more than four years, most recently purchasing other AWP and OMNI units for its high-volume DRAM production. ProMOS will use the AWP products for cleaning and etch; the RTP products will be used for silicide formation, metallization and multiple layer annealing; and the Aspen Strip products will be used in clean and photoresist strip processing.

Brad Mattson, Mattson Technology CEO, commented that this installation is significant because ProMOS is one of the leading-edge companies that is aggressively ramping up 300 mm processing technology. "This installation demonstrates ProMOS' confidence in our full range of 300 mm technology to meet the company's aggressive 300 mm program goals. We look forward to continuing our relationship with ProMOS," said Mattson.

ProMOS is a joint venture between Mosel-Vitelic Corp. and Siemens Semiconductor Group. The fab is located at Hsin-Chu Science-Based Industrial Park in Taiwan, site of the majority of the country's semiconductor manufacturing facilities.

About Mattson Technology, Inc.

Mattson Technology, Inc. is a leading supplier of semiconductor wafer processing equipment used in "front-end" fabrication of integrated circuits. The company is a market leader in dry strip and RTP equipment, and its products combine advanced process technology on high-productivity platforms backed by industry-leading support. Since beginning operations in 1989, the company’s core vision has been to help bring technology leadership and productivity gains to semiconductor manufacturers worldwide. Headquartered in Fremont, Calif., the company maintains sales and support centers throughout the United States, Europe and Asia. For more information, please contact Mattson Technology, Inc., 47131 Bayside Parkway, Fremont, Calif. 94538. Telephone: (800) MATTSON/(510) 657-5900. Fax: (510) 492-5911. Internet: www.mattson.com.