193nm Superlens Imaging Structure for 20nm Lithography Node

We are showing that a 20nm lithography resolution is theoretically feasible at a 193nm illumination wavelength if employing aluminum (Al) superlens structure with index matching layer. It is illustrated that transmissivity of evanescent waves for certain wavevector bands can be enhanced by an index matching layer. It is further shown a minimal resolution of approximately lambda/10 can be achieved by appropriately engineering mask material and superlens structure. A depth of focus of several nanometers is predicted to be possible for a periodic structure with 20nm half pitch. Assistant features were adopted in superlens structure to successfully suppress the side lobes and resolve a 20nm two-slit structure.