Immersion lithography
![In immersion lithography, light travels down through a system of lenses and then a pool of water before reaching the photoresist on top of the wafer.](/Images/godic/202502/08/Immersion_lithography_illustration.svg4544.png")
![Polarization effects in immersion lithography. For pitches where immersion lithography is relevant, the polarization will affect the intensity inside the photoresist. This example is for 56 nm half-pitch.](/Images/godic/202502/08/56_nm_hp_polarized_image4544.PNG")
Immersion lithography is a photolithography resolution enhancement technique for manufacturing integrated circuits (ICs) that replaces the usual air gap between the final lens and the wafer surface with a liquid medium that has a refractive index greater than one. The resolution is increased by a factor equal to the refractive index of the liquid. Current immersion lithography tools use highly purified water for this liquid, achieving feature sizes below 45 nanometers. ASML, Canon, and Nikon are currently the only manufacturers of immersion lithography systems. The idea for Immersion lithography was first proposed and realized in the 1980s.