Lithography light source challenges for Double Patterning and EUVL

The need for improved lithography resolution has driven the development of light sources with ever shorter wavelength. Excimer lasers have extended the exposure wavelength down to 193nm. Further resolution extension will require the introduction of Extreme UV (EUV) light source technology at 13.5nm. The traditional light source driver at each technology node has been higher power which enables increased productivity. More recently, improved light source stability, driven by tighter CD and overlay budgets for Double Patterning processes, has become more important and developments in this area will be described. The leading challenge for insertion of EUVL is source power and lifetime, which are both necessary to ensure cost effective operation. The first Laser Produced Plasma (LPP) production source using a high power CO2 laser and tin droplet targets is described. High conversion efficiency has enabled high EUV power performance. Continuous operation up to 18 hours, with stable power output, has been demonstrated. High collection efficiency is obtained using a large (5sr) multilayer mirror collector optic. The first integrated source will be delivered to support scanners for process development and insertion of EUVL at the 22nm node. A roadmap for future generations of LPP sources with scalable power will be outlined.