Long Coherence Length 193 nm Laser for High-Resolution Nano-Fabrication

Immersion lithography using available 193 nm optics and laser sources provides an attractive near-term path to reducing the printable feature sizes of integrated circuits by using a high-index fluid to reduce the wavelength at the wafer, rather than using light with higher photon energy and shorter vacuum wavelength. An interferometric immersion lithography (IIL) tool has demonstrated rapid fabrication of grating structures with half-pitches of 35 nm over exposure areas of 0.5 mm. This Phase I project involves the design of a new fiber laser based 193 nm light source with very high spatial- and temporal-coherence to allow uniform high-contrast intensity fringes (35 nm HP) to illuminate a wafer surface over a substantially larger exposure area, on the order of one square cm per exposure site. In addition, the laser will have high power stability and be sufficiently robust to allow extended periods of operation with little maintenance or operator intervention.