AUSTIN, Tex. -- Lithography experts attending International Sematech's second annual 157-nm symposium appeared to be more optimistic about the use of 157-nm exposure tools in 0.065-micron process technologies, according to the Austin-based consortium today.
The second International Symposium on 157-nm Lithography was held in Dana Point, Calif., with about 330 participants at this year's meeting. According to Sematech, substantial process was reported on a number of fronts, including 157-nm resist overlay capabilities, reticle-protecting pellicles, new optical designs using calcium-fluoride (CaF2) lens materials, and other infrastructure technologies.
Sematech also noted that laboratory systems based on 157-nm wavelength light have recently demonstrated isolated lines with dimensions of 50 nm (0.05 micron) using alternating phase-shift photomasks and a 0.6 numerical aperture (NA) exposure system. Sixty presentations were made at the three-day symposium, which was organized by Sematech in conjunction with the IMEC research group in Belgium and the Selete industry consortium in Japan.
"Based on the information presented, the confidence level in 157-nm technology continues to rise," said Rich Harbison, the 157-nm program manager at Sematech and chairman of the symposium. "While the birefringence of CaF2--the material of choice for 157nm lens--presents a new engineering challenge, the optical designers have been working on an approach to compensate for it."
Currently, 248-mn lithography--the workhorse in advanced wafer fabs for several years--is expected to support 0.13-micron (130-nm) technology in volume production, but soon new 193-nm scanners exposure tools are expected to take on the critical dimensions (CDs) in 100-to-90-nm technology nodes.
At issues is whether or not optical lithography can be fully extended with 157-nm technology to handle 0.065-micron (65-nm) processes around the middle of the decade. If not, so-called "next-generation lithography" (NGL)--such as extreme ultraviolet (EUV) or electron projection lithography (EPL)--will be needed sooner this decade.
