MTSN Mattson Technology, Inc.

Mattson Technology, Inc. (NASDAQ: MTSN), a leading supplier of advanced process equipment used to manufacture semiconductors, is set to join the broad-market Russell 3000® Index when Russell Investments reconstitutes its comprehensive set of U.S. and global equity indexes on June 25, according to a preliminary list of additions posted June 11 on www.russell.com.

Annual reconstitution of Russell's U.S. indexes captures the 4,000 largest U.S. stocks as of the end of May, ranking them by total market capitalization. Membership in the Russell 3000, which remains in place for one year, means automatic inclusion in the large-cap Russell 1000® Index or small-cap Russell 2000® Index as well as the appropriate growth and value style indexes. Russell determines membership for its equity indexes primarily by objective, market-capitalization rankings and style attributes.

Russell indexes are widely used by investment managers and institutional investors for index funds and as benchmarks for both passive and active investment strategies. An industry-leading $3.9 trillion in assets currently are benchmarked to them. These investment tools originated from Russell's multi-manager investment business in the early 1980s when the company saw the need for a more objective, market-driven set of benchmarks in order to evaluate outside investment managers.

Total returns data for the Russell 3000 and other Russell Indexes is available at http://www.russell.com/Indexes/performance/default.asp.

About Russell: Russell Investments provides strategic advice, world-class implementation, state-of-the-art performance benchmarks and a range of institutional-quality investment products. Russell has $179 billion in assets under management as of March 31, 2010, and serves individual, institutional and advisor clients in more than 40 countries. Founded in 1936, Russell is a subsidiary of The Northwestern Mutual Life Insurance Company.

About Mattson Technology, Inc. Mattson Technology, Inc. designs, manufactures and markets semiconductor wafer processing equipment used in the fabrication of integrated circuits. We are a leading supplier of plasma and rapid thermal processing equipment to the global semiconductor industry, and operate in three primary product sectors: Dry Strip, Rapid Thermal Processing and Etch. Through manufacturing and design innovation, we have produced technologically advanced systems that provide productive and cost-effective solutions for customers fabricating current- and next-generation semiconductor devices. For more information, please contact Mattson Technology, Inc., 47131 Bayside Parkway, Fremont, CA, 94538. Telephone: (800) MATTSON/(510) 657-5900. Internet: www.mattson.com.

Investor & Media Contact Laura Guerrant-Oiye Guerrant Associates tel 808-882-1467 lguerrant@guerrantir.com