High laser-resistant multilayer mirrors by nodular defect planarization [invited].

Substrate defect planarization has been shown to increase the laser resistance of 1053 nm mirror coatings to greater than 100  J/cm2, an increase of 20-fold, when tested with 10 ns laser pulses. Substrate surface particles that are overcoated with optical interference mirror coatings become nodular defects, which behave as microlenses intensifying light into the defect structure. By a discrete process of angle-dependent ion etching and unidirectional ion-beam deposition, substrate defects can be reduced in cross-sectional area by over 90%.

High-performance Mo-Si multilayer coatings for extreme-ultraviolet lithography by ion-beam deposition.

An ion-beam deposition system has been used to fabricate Mo-Si multilayer coatings for masks and imaging optics to be used for extreme-ultraviolet lithography. In addition to high reflectivity and excellent profile control, ion-beam deposition has the capability to smooth rough substrates. For example, we achieved reflectivity of 66.