Fluorine—an enabler in advanced photolithography

Fluorine—its chemical and physical properties—plays a critical role in the development of advanced photolithography. It is widely expected that, when in a few years the critical dimensions in microelectronic devices will be less than ∼70 nm, the patterning technology of choice will be based on 157 nm light generated from molecular fluorine laser medium. Lithography at 157 nm also requires major advances in areas of fluorine science, from the growth of near-perfect calcium fluoride crystals for lenses to fluorine doping of fused silica for masks to the synthesis of fluoropolymers that would serve as pellicles, photoresists, and immersion liquids. With the expected resolution of these issues, the prospects are excellent that photolithography will continue as the main semiconductor patterning technology for at least another decade.