Likely option at 32nm will be 193nm Immersion
"We forecast that 23 193nm immersion tools will sell in 2006," notes Dr. Robert N. Castellano, president of The Information Network. "Nikon will ship 10-15 units and could end up leading the market this year despite ASML's early lead. Nikon will be the first company to ship by the end of this year a hyper-NA immersion system with a 1.30 NA lens designed for 45 nm volume production."
Following dry 193nm at 65nm and immersion (wet) 193nm lithography at 45nm, the report sees three major alternatives:
• Continue increasing NA and improving resolution– Both the immersion fluid (water) and the lens materials (SiO2/CaF2) limit the NA extension
• Retain the same immersion capability but adjust the process to provide better resolution– Some sort of pattern splitting to reduce resolution demand– Several options, all costly in terms of productivity
• Switch to a completely new technology– EUVL– Something yet to be invented and developed
Progress at numerous companies and universities is being made to identify and develop High-Index Immersion liquids with n = 1.63 - 1.65 (water = 1.3). Likewise, Lutetium Aluminum Garnet has been thoroughly evaluated and is a leading candidate for a High-Index Bottom lens material.
Instead of moving to high-index materials, double exposure/double processing is being evaluated. But double patterning will require 2 full litho and etch steps. What's needed is an enhanced resist. The loss of image contrast can be avoided if the resist response is non-linear. If this material is found, 32nm IC development could begin immediately on current lithography tools.
In the EUVL arena, tool development is ahead of infrastructure development. ASML has already shipped Alpha Demo Tools. But limitations with masks, sources, resists, and contamination control exist.
