MATTSON TECHNOLOGY ANNOUNCES REVISION OF SECOND QUARTER 2001 REVENUES

Revision Has No Impact on Previously Reported Net Loss, Cash Position or Guidance for Third Quarter 2001

FREMONT, Calif. - September 5, 2001 - Mattson Technology (NASDAQ: MTSN), a leading supplier of advanced process equipment used to manufacture semiconductors, today announced that it will revise its previously reported financial results for the second quarter of 2001. At the same time, the Company confirmed its previously announced revenue guidance for the third quarter of 2001.

The revision will result in lower reported revenue for Mattson's second quarter of 2001 due to an unintentional bookkeeping error, whereby certain intercompany revenue transactions were not eliminated. The effect of the revision is to reduce revenue for the second quarter from $82.0 million to $71.4 million. Because the intercompany transactions essentially involved intercompany sales at cost, the reduction in previously reported revenues has no impact on the Company's previously reported net loss for the quarter. The revision also has no impact on the Company's cash position or future projections. Mattson intends to file an amended Report on Form 10-Q for the second quarter of 2001 by September 7, 2001.

At the same time, the Company confirmed its previously stated revenue guidance for the third quarter of 2001. The Company continues to expect that third quarter 2001 revenues, on a shipment basis, should range between $75 million and $80 million.

Ludger Viefhues, Mattson's chief financial officer, said, "The revisions being announced today result from regrettable errors and do not reflect any change in the status of the Company's products, its business model or its revenue recognition policy. " Viefhues also stated that the Company is continuing its negotiations with STEAG Electronics regarding an extension of the approximately $45 million due to Steag in conjunction with Mattson's acquisition of Steag's semiconductor operations. "We are confident that the two companies will come to an agreement to extend the repayment of these liabilities."

This press release contains forward looking statements regarding, among other matters, the Company's future prospects and near-term outlook, and customer demand and the effect of the economic downturn. Forward looking statements address matters that are subject to a number of risks and uncertainties that can cause actual results to differ significantly. In addition to the general risks associated with the slowdown in the semiconductor industry and development of complex technology, future results of the Company will depend on a variety of factors, including the timing of significant orders, push-outs and cancellations of orders by customers, the ability of the Company to timely manufacture and deliver ordered products, the ability of the Company to bring new systems to market, the timing of new product releases by the Company's competitors, other competitive factors, and risks of integration following the STEAG-CFM acquisitions. Reference is made to the Company's filings with the Securities and Exchange Commission for further discussion of risks and uncertainties regarding the Company's business.

MATTSON TECHNOLOGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATED BALANCE SHEETS
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MATTSON TECHNOLOGY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
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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.