2. Optical lithography: issues and challenges

Optical lithography, also known as photolithography, is indisputably the main method for mass-producing microelectronics circuits. It involves etching the patterns to be reproduced (circuits) onto a photosensitive polymer. This polymer pattern is then transferred to the silicon wafer on which the thin polymer layer has been deposited. Since the 1970s, this technique has undergone a number of evolutions, described in detail in reference . These developments have involved :

• the wavelength of light ;

• photosensitive...