ATMI and SemEquip Form Strategic Partnership; Cluster Beam Ion Implant Key to Next Generation Semiconductors.

DANBURY, Conn. -- ATMI, Inc. (Nasdaq: ATMI), a supplier of materials and materials packaging to the world's leading semiconductor manufacturers, today announced it has formed a strategic partnership with SemEquip, Inc. to exclusively market and sell their ClusterBoron(TM) ion implant materials. ATMI and SemEquip will co-develop new delivery systems for ClusterBoron materials targeted for chip generations at and below 65 nanometers. The strategic partnership includes an equity investment by ATMI in SemEquip's recently completed round of venture financing.

Jim Dietz, ATMI Team Leader, Implant Module, said, "SemEquip's team includes some of the foremost implant source and beam-line designers in the world. With their process know-how and our materials focus, we can speed the development and adoption of new cluster materials for next generation ion implantation processes. The addition of new ClusterBoron products to our current portfolio of SDS(R) & VAC(R) products strengthens our position as the leading supplier of advanced materials and materials packaging for ion implant applications."

Brian Cohen, Chief Executive Officer, SemEquip said, "As semiconductors become smaller and more complex, ion implant becomes proportionately more challenging. Our ClusterIon(TM) source performance is up to ten times more productive for advanced processes than conventional ion sources at 90-nanometer production. Collaborating with ATMI will help to speed market penetration and the development of the materials supply chain. We plan to demonstrate wafer capability this fall, with commercial materials and delivery systems becoming available in 2005."

About Cluster Beams & Ion Implantation

As semiconductor devices shrink in size, the energy of ion implantation must also decline proportionately. As energy levels decline, conventional implant systems cannot maintain wafer throughputs because of fundamental physical limits of the ion beams.

Cluster ions include many dopant atoms per molecule. This way, the implanter can operate at a higher energy level and spread the process energy among the number of dopant atoms of the molecule. Using cluster ions, ultra shallow junctions can be created at higher implant energies, the net effect of which is restoring or improving the productivity of the ion implanter.

About SemEquip, Inc.

SemEquip Inc. (North Billerica, MA) is a research and development company developing cluster beam ion implantation sources and delivery systems to improve efficiencies and productivity in the fabrication of semiconductors. SemEquip's mission is to revolutionize the ion implantation original equipment market with cluster beam ion implantation. SemEquip holds patents or has patents pending on most of its products.

ATMI provides specialty materials and materials packaging to the worldwide semiconductor industry. As the Source of Semiconductor Process Efficiency, ATMI helps customers improve wafer yields and lower operating costs. For more information, please visit atmi.com.

Statements contained herein that relate to ATMI's future performance, including, without limitation, statements with respect to ATMI's anticipated results of operations or level of business for 2004 or any other future period, are forward-looking statements within the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Such statements are based on current expectations only and are subject to certain risks, uncertainties, and assumptions, including, but not limited to: changes in semiconductor industry growth or ATMI's markets; competition, problems, or delays developing and commercializing new products; problems or delays in integrating acquired operations and businesses into ATMI; problems or delays associated with any restructuring activity, or implementing any strategy, including resolution of the various discontinued elements of ATMI's Technologies segment; and other factors discussed in ATMI's filings with the Securities and Exchange Commission. Such risks and uncertainties could cause actual results to differ from those projected. ATMI undertakes no obligation to publicly update or revise any forward-looking statements, whether because of new information, future events or otherwise.