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Product Briefing Outline: Carl Zeiss SMT has announced the development of its lithography optical system, ‘Starlith' 1900i. The new system has a numerical aperture (NA) of 1.35, the highest NA currently designed, that will be used for volume chip production at 40nm half-pitch node. The system will be part of ASML's new ‘TWINSCAN' XT:1900i immersion lithography tool that will begin shipments in 2007.

Problem: In order to increase the NA much beyond .93, traditional lens designs required highly complex and large lens arrangements that would be difficult to build and cost preventative. To boost NA further, water is used between the final lens and the wafer. This allows catadioptric lens configurations to be used closer to the refractive index of water (1.44). The higher NA improves the ability to image feature sizes below 50nm.
 
Solution: The proprietary ‘Catadioptric Inline Multi Mirror Design' is designed to allow standard fitment within existing ASML lithography platforms, using an even number of mirrors as part of the catadioptric lens assembly, resulting in no image flip and the use of conventional mask technology. Essential for printing 40nm features with large process windows is the inclusion of a new illuminator ‘AERIAL XP.' Special emphasis has been placed on polarization control in the illumination system. The wide variety of possible illumination settings enables chip manufacturers to fine-tune optimized illumination conditions matching the relevant device features (mask structure and mask type).

Applications: ASML ‘TWINSCAN' XT:1900i immersion lithography tool.

Platform: The ‘Starlith' 1900i lens is based on the proprietary "Catadioptric Inline Multi Mirror Design", enabling a compact single barrel design. Since an even number of mirrors is used, there is no image flip, and the same masks as in all other system can be used. The system will be part of ASML's new ‘TWINSCAN' XT:1900i immersion lithography tool.

Availability: Mid-2007 onwards.