Toralf Gruner

Advanced wavefront engineering for improved imaging and overlay applications on a 1.35 NA immersion scanner

In this paper we describe the basic principle of FlexWave, a new high resolution wavefront manipulator, and discuss experimental data on imaging, focus and overlay. For this we integrated the FlexWave module in a 1.35 NA immersion scanner. With FlexWave we can perform both static and dynamic wavefront corrections. Wavefront control with FlexWave minimizes lens aberrations under high productivity usage of the scanner, hence maintaining overlay and focus performance, but moreover, the high resolution wavefront tuning can be used to compensate for litho related effects. Especially now mask 3D effects are becoming a major error component, additional tuning is required. Optimized wavefront can be achieved with computational lithography, by either co-optimizing source, mask, and Wavefront Target prior to tape-out, or by tuning Wavefront Targets for specific masks and scanners after the reticle is made.

Optical lithography with 157-nm technology

This paper presents the progress of the 157 nm lithography program at ASML and Carl Zeiss SMT in 2003. The major technical problems are solved and the first full field 157 nm scanner was shipped to the industry for starting the process development. The progress in CaF2 material as well as production of CaF2 lens elements allow system to be produced for the 55 nm node. Contamination is shown to be at very low levels and a solution to reduce the influence of hard pellicles below 1 nm distortion is found. The first imaging results show a high depth of focus for 75 nm dense lines.