**2.4 Conclusion**

184 Advances in Unconventional Lithography

For exposure equipment, our simulation assumed use of the Nikon EUV-1 installed at Selete [19]. Fig.17 shows the simulation results. The indicated exposure value is the exposure level (E0) that achieved 1:1 resolution from a 28-nm L&S pattern. The development conditions called for 2.38% TMAH and development time of 60 seconds. The quencher diffusion length

and PAG diffusion length were set to 20 nm and 10 nm, respectively.

Fig. 17. Simulation results

We compared the results of EUVL simulations based on parameters obtained with KrF exposures to the results of EUVL simulations based on parameters obtained with EUV exposures. The former resulted in approximately 20% higher simulation sensitivity, but we saw no major differences in shape. Using parameters obtained with KrF exposure is a roundabout way to perform EUVL simulations. Since EUV exposures in many cases are not readily available, a valid option would appear to be to acquire simulation parameters through KrF exposures and to use these parameters as initial values in calculations for EUVL simulations.
