Progress in deep-UV liquid immersion mastering of high density optical discs

In the blue generation of optical discs, the ROM capacity required on a single layer of a 12 cm disc is 25 GB and higher. Far field deep-UV mastering equipment has been successfully applied to record densities up to 20 GB. Higher densities, however, are increasingly difficult to master and a further reduction of the writing spot of the recorder seems to be required. Apart from the option to switch to e-beam recording, liquid immersion deep-UV mastering offers an interesting possibility to extend the density range of conventional laser beam recorders. In this concept, a resolution improvement is realized by increasing the numerical aperture to values above 1. In this paper experiments are described aimed at the mastering of high density ROM discs by means of the deep-UV liquid immersion technique.