IBM says litho chemical better for environment

SANTA JOSE, Calif.—IBM Corp. said Tuesday (Feb. 23) that researchers from its Semiconductor Research and Development Center have developed a fluorine-free photo-acid generator (PAG) for use in 193-nm lithography, billed as a more environmentally friendly alternative than the fluorine-based perfluorooctane sulfonate and perfluorooctanoic acid currently in use.

According to IBM, research has shown that the fluorine-based compounds can persist in the environment and gradually increase in concentration over time. A paper on the new PAG was presented by IBM researchers at the SPIE Advanced Lithograph conference Tuesday.

A PAG is used in microlithography to help amplify and clarify the circuit image, IBM said. IBM researchers have demonstrated the new chemicals meet the performance requirements for both dry and immersion 193-nm lithography, with equivalent performance in 45-nm technology for optical transparency, solubility, thermal stability and shelf-life, the company said.

IBM holds several patents on the new compounds and is in discussions with a number of chemical suppliers concerning their license, the company said.

"This latest fluorine-free photo-acid generator invention adds another dimension to IBM's intellectual property portfolio and provides unique opportunities to help develop environmentally preferable patterning materials through strategic engagements with the photoresist industry," said Rao Varanasi, manager of patterning materials research and development for IBM and one of the papers authors, in a statement.