The advantage of excimer lasers over conventional UV lamps for microlithography will be discussed and the difficulties encountered will be reviewed. The first application of excimer lasers was in contact printing where the short wavelength of 193 nm of ArF is used to produce sub-half-micron resolution typically on GaAs chips. The first use of excimer lasers in the field of projection printing was in the area of reticle manufacturing. 308 nm XeC1 lasers are used in pattern generators to produce the pixels of the reticle pattern. A very promising field of applications is in the domaine of reduction wafer steppers which produce a demagnified image of the reticle on silicon wafer. Despite the numerous problems in designing a DUV stepper, the wafer stepper with excimer laser source seems to be the logical choice for the next generation of highly integrated circuit manufacturing. Finally, a promising but still distant possible application could be a 1 : 1 print using phase conjugation to circumvent the need for highly sophisticated optics between reticle and wafer.
Elmar Cullmann, Elmar Cullmann,
"Excimer Lasers For Lithography Applications", Proc. SPIE 1138, Optical Microlithography and Metrology for Microcircuit Fabrication, (11 October 1989); doi: 10.1117/12.961751; https://doi.org/10.1117/12.961751