Immersion and EUV Lithography

Semiconductor technology has advanced to single-digit nanometer dimensions for the circuit elements. The minimum feature size has reached subwavelength dimension. Many resolution enhancement techniques have been developed to extend the resolution limit of optical lithography systems, namely illumination optimization, phase-shifting masks, and proximity corrections. Needless to say, the actinic wavelength and the numerical aperture of the imaging lens have been reduced in stages, The most recent innovations are Immersion lithography and Extreme UV (EUV) lithography