CCMP CMC Materials Inc

Cabot Microelectronics Corporation (Nasdaq:CCMP), the leading supplier of chemical mechanical planarization (CMP) slurries to the semiconductor industry, announced today that it will participate at CSFB's Boston Small/Mid Cap Semi Cap Equipment Conference on Wednesday, June 22, 2005. About Cabot Microelectronics Cabot Microelectronics Corporation, headquartered in Aurora, Illinois, is the leading supplier of CMP slurries for polishing various materials used in semiconductor manufacturing processes. The company's products play a critical role in the production of the most advanced semiconductor devices, enabling the manufacture of smaller, faster and more complex devices by its customers. For more information about Cabot Microelectronics Corporation visit www.cabotcmp.com or contact the company at (630) 499-2600. Safe Harbor Statement This news release may include statements that constitute "forward-looking statements" within the meaning of federal securities regulations. These forward-looking statements include statements related to future sales and operating results, company and industry growth and trends, growth of the markets in which the company participates, international events, product performance, new product introductions, development of new products and technologies, and the construction of new facilities by Cabot Microelectronics. These forward-looking statements involve a number of risks, uncertainties, and other factors, including those described from time to time in Cabot Microelectronics' filings with the Securities and Exchange Commission (SEC), that could cause actual results to differ materially from those described by these forward-looking statements. In particular, see "Risks Relating to Our Business" in Management's Discussion and Analysis in our quarterly report on Form 10-Q for the quarter ended March 31, 2005, and our Annual Report on Form 10-K for the fiscal year ended September 30, 2004, both filed with the SEC. Cabot Microelectronics Corporation assumes no obligation to update this forward-looking information.