As the design rules to make integrated circuits with features less than 0.25 micrometers are emerging, it appears that conventional deep UV photolithography will not be able to support these new generation IC technologies. There are however other possibilities such as enhanced optics, proximity x-ray and projection electron-beam which extend the state of lithography below 0.25 micrometers . AT&T is in a unique position to evaluate these new technologies since we have active programs in each of these areas. It is clear that the success of any of these new techniques is directly connected to the ability to manufacture the corresponding mask.
Regine G. Tarascon,
"Recent advances in mask-making technology at AT&T", Proc. SPIE 2512, Photomask and X-Ray Mask Technology II, (3 July 1995); doi: 10.1117/12.212799; https://doi.org/10.1117/12.212799