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Water based immersion lithography is now widely recognized a key enabler for continued device shrinks beyond the limits of classical dry lithography. Since 2004, ASML has shipped multiple TWINSCAN immersion systems to IC manufacturers, which have facilitated immersion process integration and optimization. In early 2006, ASML commenced shipment of the first immersion systems for 45nm volume production, featuring an innovative in-line catadioptric lens with a numerical aperture (NA) of 1.2 and a high transmission polarized illumination system. A natural extension of this technology, the XT:1900Gi supports the continued drive for device shrinks that the semiconductor industry demands by offering 40nm half-pitch resolution. This tool features a projection lens based on the already proven in-line catadioptric lens concept but with an enhanced, industry leading NA of 1.35. In this paper, we will discuss the immersion technology challenges and solutions, and present performance data for this latest dual wafer stage TWINSCAN immersion system. |
