Immersion lithography topcoat is an option for defect control but is it really necessary?

If an exposure tool is fast enough, the light does its work before the water can sink in.

A problem with the current tools in the field is that they don't pre-wet the photoresist, making defects more likely.

A modification of the litho track can do prewet (like a puddle) before exposure. Is it really necessary? It seems easier to program the wetting sequence in the immersion chamber itself.

Almost all the immersion defect horror stories come from ASML demo systems where the water is pushed across the wafer, with high potential of leaving watermarks and drying stains. A lot of this can be totally avoided with Nikon's Local Fill Technology.

Nikon pushes the envelope for 193 nm exposure technology with the NSR-S610C. The S610C begins shipping in Q4 2006.

The S610C uses an innovative multi-axial catadioptric lens design to deliver a 1.30 NA with all aspects of performance optimized for 45 nm memory requirements. The S610C lens design enables imaging below 45 nm with a superior depth of focus, and the fourth generation of POLANO polarization control provides enhanced image contrast without any loss of illumination power or throughput.

Nikon’s innovative Local Fill Technology combines the proprietary nozzle design, high water flow rate, and airless fluid handling that consistently delivers performance free of immersion-specific defects. Nikon Local Fill Technology is compatible with a wide variety of ArF resists and topcoats, enabling defect levels on par with today’s most advanced dry ArF systems at the maximum throughput.

The Nikon Tandem Stage was designed for high volume manufacturing, providing optimized performance and efficiency for immersion lithography. The exposure stage processes wafers at very high rates, while the calibration stage is used for calibrations during wafer exchange. The Tandem Stage enables throughput ≥ 130 wafers per hour, and delivers wet-dry overlay matching equivalent to dry system performance.

Ideally maybe you would need an amphiphile monolayer on a hydrophobic coat? Like a surfactant? The water would wet easily the hydrophilic top surface but not penetrate the hydrophobic surfaces underneath.

It's funny how all the defect horror stories have been from ASML tools. On the other hand, no press on Nikon (how come?). I have heard you had to modify the ASML tool (and take the risk of breaking the warranty) to make it essentially defect-free.