Key Parameters Demonstrated for High-Volume EUV Lithography Sources

摘要

EUV lithography is the leading option for critical-layer imaging beyond 193 nm immersion and double patterning. One of the key challenges for the successful introduction of EUV lithography is the development of a high-power, long-lifetime source. LPP EUV light sources have been shown to be the most promising source technology to scale power to meet the throughput requirements as the lithography tools evolve over their life cycle. We have chosen an LPP architecture using the high-CE combination of 10.6 μm CO_2 laser radiation and a tin source element, which has shown CE well in excess of 4%. High CE is the key to a cost-effective solution for chipmakers. High-power, high-repetition-rate CO_2 laser technology has been validated and is operational above the 12 kW level. High-CE operation has been demonstrated on droplet targets, and measured. EUV burst power of 300 W at the plasma and 100 W at IF has recently been achieved. This is the target power level needed for first-generation source products to support pre-production EUV exposure tools. Additional development over the next year will focus on increasing average power to the 100 W level by increasing duty-cycle scaling. Debris mitigation techniques have been developed and shown to suppress energetic ions, which can erode collection optics and reduce reflectivity. It is estimated that the lifetime of the collector coating can reach 10~(12) pulses, or one year of operation. A sub-aperture normal-incidence collector mirror of 320 mm diameter with high-temperature graded multilayer coating has been developed, including the fabrication infrastructure. Over the next year, the collection optics, together with debris mitigation technology, will be integrated and tested. Early versions of the integrated system are targeted for delivery by the end of 2008.