Integrated circuits(IC) are produced using conventional photolithography technology. To create the narrowest possible current paths on the chips, blue or violet light is used because it has the smallest wavelengths. These are around 430 nm to 500 nm.
Due to the miniaturization of microelectronics and especially of nanoelectronics, the structural widths of the current paths are constantly becoming narrower and are already well below 20 nm. This means that lithographic exposure with blue and violet light can no longer be used because the wavelengths of blue light are greater than the required structure widths.
Extreme ultraviolet lithography (EUVL) or nanolithography circumvents these limitations by using extreme ultraviolet light( EUV). The wavelength range for this is between 100 nm and 13 nm. In optical lithography, the focusing of the light beam can be improved by numerical aperture( NA) of the imaging optics. With a numerical aperture of 0.33, structure widths of 2 nm and below are achieved.
Since the refraction and diffraction of the light beam through the optical lenses in EUV optical lithography has a different behavior than visible light, the circuit patterns can also be plotted using mirror projections. With this technique, structure widths of 20 nm and 10 nm can be realized. However, the EUV light cannot be projected onto the wafer with optical lithography because the refraction and diffraction by the optical lenses has a different behavior than with visible light. The projection of the circuit patterns is done reflectively via mirrors. Structure widths of 20 nm and 10 nm can be realized with this technique.