Immersion-Lithography Tool Dives Toward 70- To 45-nm Features

Thanks to a joint effort, an immersion lithography tool with an ultra-high numerical aperture (NA = 1.3) and 193-nm wavelength is on the horizon. Exitech's MS-193i microexposure device will help speed the development of critical infrastructure for immersion lithography at International Sematech's Immersion Technology Center in Austin, Texas.

Immersion lithography interposes a liquid between an exposure tool's projection lens and the wafer. The liquid enhances the resolution, enabling the system to produce smaller features. By using immersion lithography at 193 nm, much of the "dry" 193-nm lithography infrastructure--like laser sources, reticles, and tool architecture--can be incorporated with minimal enhancements. This will help lower overall development costs, since much of the infrastructure can be reused. In its deionized, degassed, purified, and filtered form, water can serve as the immersion liquid.

Due to be installed at Sematech in the third quarter of 2005, the MS-193i incorporates a 1.3-NA catadioptric, 0.4-mm field, water-immersion imaging objective lens developed by Corning Tropel. With a 4-kHz, linearly polarized, 193-nm natural bandwidth argon-fluoride laser source from Lambda Physik, the tool will image minimum feature sizes of 70 and 45 nm using binary and phase-shifting masks, respectively.